Biomedical subjects

W Ptak

Publications and source records attributed to W Ptak.

At least 37 records · Page 2Linked to original sources

PubMed1996

Delayed-type hypersensitivity in mast cell-deficient mice: dependence on platelets for expression of contact sensitivity.

Previous studies of cutaneous T cell-mediated responses in mice have obtained pharmacologic, morphologic, and immunologic evidence pointing to a critical role for local mast cells in release of the vasoactive amine serotonin (5-HT) to mediate early, initiating events that are required for elicitation of these responses. However, the role of mast cells in initiating these T cell-mediated cutaneous responses has been questioned due to the presence of relatively intact delayed-type hypersensitivity responses, such as contact sensitivity (CS), in mast cell-deficient mice whose skin contains only 1 % normal mast cell numbers. The contribution of other potential local sources of 5-HT, such as circulating platelets, at the site of a delayed-type hypersensitivity or CS response in these mast cell-deficient strains, has not been investigated. Therefore, we studied the effect of systemic platelet depletion, produced with an anti-platelet Ab, on blood and tissue levels of 5-HT, and on in vivo T cell-mediated cutaneous sensitivity responses, in W/Wv and Sl/Sld mast cell-deficient mice. The results showed that: 1) platelet depletion severely reduced whole blood 5-HT; 2) tissue levels of 5-HT, in mast cell-deficient mice, depended in large part on the presence of circulating platelets, and 3) specific depletion of platelets markedly suppressed CS responses in both W/Wv and Sl/Sld mast cell-deficient mice, and only moderately reduced CS in normal +/+ congenic mast cell-sufficient controls, but did not decrease CS in beige mice, with platelet granules that are defective in storage of 5-HT. We concluded that platelets may provide 5-HT crucial for the initiation of cutaneous T cell-mediated immune responses, such as CS.

Animals↗

PubMed1996

Immune or normal gamma delta T cells that assist alpha beta T cells in elicitation of contact sensitivity preferentially use V gamma 5 and V delta 4 variable region gene segments.

In the current study, we confirmed previous findings suggesting that gamma delta T cells were involved in the successful adoptive cell transfer of contact sensitivity (CS) by alpha beta CS-effector T cells. In this study, we used hamster anti-mouse gamma delta-TCR mAb treatment of CS-effector T cells, followed by enrichment and removal of the gamma delta T cells with goat anti-hamster Ig-linked magnetic beads, or by addition of hemolytic rabbit C. This removal of gamma delta T cells abrogated adoptive cell transfers of CS, despite the presence of alpha beta T cells that are known to mediate CS. FACS analysis documented enrichment of gamma delta T cells rising from 1 to 2% of the starting cells, to 60 to 95% of the magnetic bead adherent cells. Adoptive cell transfer of CS was reconstituted by adding back to the alpha beta cells, highly enriched gamma delta cells attached to anti-gamma delta-TCR magnetic beads. Not only were gamma delta-enriched T cells from sensitized mice able to assist immune CS-effector alpha beta T cells, but gamma delta T cells from normal nonimmune mice also had CS-assisting activity, and furthermore, neither were MHC-restricted in this function. Thus, CS-assisting gamma delta T cells were present endogenously in normal mice without prior immunization, and acted without Ag specificity and without MHC restriction, to assist CS-effector alpha beta T cells. Similar studies, with hamster mAbs specific for V gamma and V delta portions of gamma delta-TCR, demonstrated that the gamma delta T cells that assisted the CS-effector alpha beta T cells preferentially expressed V gamma 5 and V delta 4 in their TCR. PCR analysis on extracted mRNA showed that V gamma 5 and V delta 4 gene segments indeed were rearranged and expressed in the sensitized and normal lymph nodes; and one-and two-color FACS analysis of magnetic bead-fractionated cells suggested that V gamma 5 and V delta 4 were expressed on the same T cells. In summary, these results demonstrated that V gamma 5+, V delta 4+, gamma delta T cells were needed to assist alpha beta effector T cells in the adoptive cell transfer of CS.

Animals↗

PubMed1996

The in vivo and in vitro effects of an alkylating agent, mechlorethamine, on IL-6 production in mice and the role of macrophages.

Alkylating agents, cyclophosphamide (CY) and the related compound mechlorethamine (NM), significantly increase in vivo the blood level of IL-6 but not of IL-1. Since in vitro CY is inactive we have used in our experiments NM, a compound structurally and functionally related to phosphoramide mustard, the natural biologically active metabolite of CY. Thioglycollate or oil-induced peritonal macrophages (Mf) of four different mouse strains treated with NM produce significantly more IL-6 than the non-treated cells. In contrast, under these conditions, the production of IL-1, TNF alpha and NO/NO2 radicals is not affected. The NM-induced elevated production of IL-6 by Mf could not be further increased by the treatment of cells with LPS, which may suggest that both agonists stimulate the same signalling pathway. The antineoplastic activity of the alkylating agents like CY or NM is usually attributed to the interstrand cross-linking of the DNA of the dividing cells. Our experiments can be tentatively interpreted as the induced overplus of IL-6 can also contribute to the stimulation of the cytotoxic NK-cells.

Alkylating Agents↗

PubMed1995

Adoptive cell transfer of contact sensitivity-initiation mediated by nonimmune cells sensitized with monoclonal IgE antibodies. Dependence on host skin mast cells.

A role for mast cell release of serotonin (5-HT), via Ag-specific factors derived from Thy-1+ B220+ lymphoid cells in the initiation of murine contact sensitivity (CS) has been suggested. However, because CS in mast cell-deficient mice was intact, a role for mast cells in CS initiation was unclear. Therefore, we examined whether CS could be initiated by i.v. injection of nonimmune mixed lymphoid cells that were sensitized in vitro with IgE. When naive mice received IgE-sensitized nonimmune spleen or lymph node cells, or IgE-sensitized purified mast cells, together with immune CS-effector B220- T cells, which therefore were depleted of CS-initiating, Thy-1+, B220+ cells, which could not transfer CS, then reconstitution of CS occurred. Mast cell-deficient W/Wv mice could not elicit this IgE-dependent CS ear swelling, but when mast cell deficiency was reversed by ear injection of normal bone marrow-derived cultured mast cells, then CS was restored. In vitro pretreatment with irrelevant monoclonal anti-OVA IgE prevented CS initiation mediated by Ag-specific, IgE mAb-sensitized cells, presumably by blocking sensitization with IgE. Thus Fc epsilon R on the normal lymphoid cells were involved. When ketanserin, a 5-HT2 receptor antagonist, was injected i.v. before cell transfer, CS initiation via IgE-sensitized cells and CS were no longer elicited. Thus, in this system, IgE Abs bound to circulating IgE Fc epsilon R bearing lymphoid cells sensitized in vitro (most likely basophils), probably mediated early activation of these circulating basophils to release mediators, causing 5-HT release from cutaneous mast cells, to mediate CS initiation.

Animals↗

PubMed1995

Gamma delta T cells in normal spleen assist immunized alpha beta T cells in the adoptive cell transfer of contact sensitivity. Effect of Bordetella pertussis, cyclophosphamide, and antibodies to determinants on suppressor cells.

Our prior studies showed that gamma delta T cells were required to assist alpha beta T cells in the successful adoptive cell transfer of contact sensitivity (CS) responsiveness. These TCR-gamma delta+ regulatory T cells in immune spleen and lymph node were CD3+, CD4-, CD8+, nonantigen-specific, and non-MHC-restricted. In the current work, experiments were conducted to determine the mechanisms of how the gamma delta T cells were required to assist the alpha beta T cells in CS. We found that similar regulatory gamma delta T cells were in the spleen of normal mice, but not in the spleen of nude nor SCID mice, suggesting that the regulatory gamma delta T cells were present before immunization and required the thymus for differentiation, and also required rearrangements of gamma delta V gene segments. Treatment of cell transfer recipient mice with Bordetella pertussis (Bp), or with a low dose of cyclophosphamide (50 mg/kg), restored the ability of alpha beta+ gamma delta- T cells to transfer CS. This and other results suggested that Bp caused the CS-assisting gamma delta T cells to leave the lymphoid organs (such as the spleen) and enter the circulation, and only then to be able to assist the TCR-alpha beta+ CS-effector T cells. This effect needed the simultaneous i.v. injection of the CS-effector alpha beta T cells and the CS-assisting gamma delta T cells. The results also suggested that treatment with cyclophosphamide inactivated suppressor T cells in the recipients that acted to inhibit the alpha beta T cell transfer of CS, and thus that the CS-assisting gamma delta T cells acted by protecting the CS-effector alpha beta T cells from this endogenous suppression. This suppression of CS transfers also was eliminated by treatment of recipients with two different mAbs to determinants on suppressor T cells. In conclusion, we have described regulatory TCR-gamma delta+ CS-assisting/protecting T cells that are non-antigen-specific, non-MHC-restricted, CD3+, CD8+ gamma delta T cells that may assist adoptive transferring CS-effector alpha beta T cells by making these effector T cells resistant to suppressor T cells in the normal recipients.

Animals↗

PubMed1995

Induction of tolerance by administration of hapten-immunoglobulin conjugates is associated with decreased IL-2 and IL-4 production.

Intravenous administration of trinitrophenyl-modified isologous immunoglobulin-induced nonresponsiveness to subsequent epicutaneous painting of sensitizing doses of trinitrochlorobenzene. Isologous immunoglobulin with various degrees of trinitrophenyl substitution (11.2, 14.3, 27 and 47.3) prevented sensitization. The suppression of contact hypersensitivity was dependent on the dose of tolerogen and was hapten specific. Tolerance was inducible in mice of the strains CBA (H-2k), C57BL/6 (H-2b), and DBA/2 (H-2d) but not in Balb/C (H-2d) mice, suggesting that this trait maps outside the murine major histocompatibility complex. Tolerance induced by trinitrophenyl-modified immunoglobulin was associated with decreased hapten-induced proliferation of draining lymph-node cells. Unlike in other models of tolerance in which a decreased interleukin-2 to interleukin-4 ratio can be observed, administration of tolerizing trinitrophenylated immunoglobulin was associated with deficient hapten-induced release of both interleukin-2 and interleukin-4.

Animals↗

PubMed1994

Monoclonal, antigen-specific, T cell contrasuppressor factor expresses determinants of TCR alpha-chain (not necessarily TCR beta-chain), having a molecular mass of about 40 kDa.

Contrasuppression is a regulatory T cell activity that acts on helper and contact sensitivity effector T cells to protect them from the action of suppressor T cells. In this study, we examined a monoclonal Ag-specific T cell-secreted contrasuppressor factor (TcsF) with Ag specificity for the hapten TNP (trinitrophenyl). This factor positively influences the adoptive cell transfer of contact sensitivity in the presence of active suppression. Results presented in this report demonstrate a relationship between TcsF and the alpha,beta-T cell receptor (TCR). We found that TcsF bound to mAb anti-TCR-alpha (H28) and to mAb anti-TCR-beta (H57) immunoaffinity columns, but not to a mAb anti-TCR-gamma,delta (UC7) column. The bound contrasuppressor activity could be recovered from these affinity columns by base elution. Reduction of TcsF with DTT followed by alkylation with methylmethanethiosulfonate (MMTS), demonstrated that the active subunit of TcsF bound to and eluted from anti-TCR-alpha, but not to anti-TCR-beta columns. The active TcsF that bound to anti-TCR-alpha but not to the anti-TCR-beta column was shown subsequently to have the ability to bind to specific Ag columns TNP-BSA and TNP-BGG Sepharose 4B. The TcsF could be successfully recovered later from Ag columns; thus suggesting that the Ag-binding domain for mAb, and the biologic activity, resides on the TCR-alpha chain of TcsF. Separation of TcsF on SDS-PAGE under reducing conditions, followed by elution and renaturation of proteins from the gel slices, showed that a 35 to 40 kDa protein had the T cell contrasuppressive activity. Western blot analysis of nonreduced TNP-binding TcsF revealed TCR-alpha,beta determinants on an 80-kDa native molecule similar to TCR-alpha,beta from a helper T cell clone. In summary, Ag-specific, Ag-binding T cell-derived contrasuppressor factor has serologic determinants of TCR-alpha and TCR-beta chains, but the TCR-alpha chain and not the TCR-beta chain is required for biologic function. This TCR-alpha determinant-containing factor is absorbed by specific Ag (TNP) columns. SDS-PAGE analysis under reducing conditions suggested a molecular weight of about 35 to 40 kDa for the TNP-specific TcsF. The mechanism of action of the TCR-alpha-containing contrasuppressor factor in the regulation contact sensitivity is discussed.

Animals↗

PubMed1994

Cyclophosphamide uncovers two separate macrophage subpopulations with opposite immunogenic potential and different patterns of monokine production.

As shown previously, thioglycollate-induced peritoneal macrophages consist of two subpopulations which differ morphologically and functionally. When tagged with trinitrophenyl hapten (TNP), one macrophage subpopulation induced in vivo effector cells (Th1) of contact sensitivity (CS) reaction, while the other induced suppressor T cells (Ts) which inhibit CS and are highly sensitive to the in vivo action of cyclophosphamide (CY). Our present experiments show that CY-resistant (Th inducers) and CY-sensitive macrophages (Ts inducers) differ also in the spectrum of biologically relevant molecules which they secrete when stimulated by LPS. Thus macrophages which preferentially induce Th1 cells have a cytokine pattern IL-1LOW, IL-6HIGH, TNF-alpha LOW, while macrophages which recruit Ts cells are IL-1HIGH, IL-6LOW, TNF-alpha HIGH. TH1 inducers produced also somewhat better PGE2 then Ts inducers. Production of reactive nitrogen intermediates (NO/NO2-) was similar in both groups of macrophages. The reasons for the differential effect of CY on these two populations is not clear at present, although it is known that CY metabolites can bind to sulfhydryl groups on antigen presenting cells (APC) and thereby up- or downregulate the antigen presenting capacities of separate subpopulations of APC.

Animals↗

PubMed1994

Generation of anti-hapten T cell cytotoxicity in vivo. Relationship to contact sensitivity and the role of contrasuppression.

Immunization procedures that induce contact sensitivity to the trinitrophenyl (TNP) hapten in vivo were investigated for their ability to induce TNP-specific cytotoxic T lymphocytes in vivo. Spleen cells from C3H/HeN mice primed for CS responses either by the topical application of picryl chloride or by the adoptive transfer of PCL immune cells show little or no cytolytic activity in vitro against TNP-coupled target cells. Intravenous immunization with TNP-substituted syngeneic spleen cells, a procedure known to make animals unresponsive to agents normally inducing CS, also failed to induce cytolytic activity in spleen cells. However, both PCL sensitization and adoptive transfer, when combined with the injection of TNP-substituted syngeneic spleen cells, induce significant cytolytic activity against TNP-haptenated BW5147 target cells in vitro. Furthermore, i.v. injection of TNP-spleen cells with surface-bound immune complexes of the IgM or IgG1 isotypes, or with a monoclonal TNP-specific contrasuppressor T cell factor also induces strong antigen-specific cytolytic activity against TNP modified targets. TcsF bears serological determinants of T cell receptor alpha and beta chains and adheres to specific antigen columns. All these immunization regimens were shown to induce CS to TNP as well as the generation of contrasuppressor T cells. The CTL generated in the spleens of immunized mice are Thy1+ CD8+ T cells an are antigen-specific and genetically restricted. The implications of these results with respect to the mechanisms by which cytolytic responses are controlled in vivo is discussed.

Animals↗

PubMed1993

Distinct populations of antigen-presenting macrophages are required for induction of effector and regulatory cells in contact sensitivity response in mice.

Macrophages (Mf) and other antigen-presenting cells (APCs) are able to induce both immune and regulatory T cells. We compared the antigen-presenting activities of different subpopulations of thioglycolate-induced peritoneal macrophages from mice that were or were not treated with cyclophosphamide (CY) by several functional (adherence and phagocytosis) and morphologic (phenotypic) markers (FcR, Ia). Different subpopulations of macrophages were derivatized with trinitrophenyl and injected intravenously into recipients, which were tested directly for a contact sensitivity (CS) reaction or for the presence of efferent suppressor T (Ts) cells in passive transfer experiments. Our results demonstrate that peritoneal macrophages are both morphologically and functionally heterogeneous. Macrophages that induce immune cells that mediate CS have characteristics different from those that induce Ts cells. They accumulate in the low-density cell fraction on a discontinuous Ficoll gradient, are insensitive to treatment in vivo with low doses of CY, phagocytose poorly and adhere to plastic, and perhaps have low expression of FcRI and FcRII. Both macrophage fractions seem not to differ in expression of Ia, Mac-1, and Mac-3 antigens. It is argued that low doses of CY abrogate suppression in vivo by selective action on Ts cells. Our results confirm that at least a portion of the action of CY may be due to its influence on certain subpopulations of APCs.

Animals↗

PubMed1992

Gamma delta T cells assist alpha beta T cells in adoptive transfer of contact sensitivity.

Cutaneous immune responses to contact sensitizers such as picryl chloride or oxazolone, are classical manifestations of T cell-mediated immunity in vivo. In fact, the first documentation of T cell-mediated immunity was the ability to adoptively transfer contact sensitivity (CS) responses. Although it is now clear that Ag/MHC-restricted alpha beta TCR positive effector T cells are responsible for 24 to 48 h CS responses, other subsets of Thy-1+ cells in mice also participate in the elicitation of CS. Thus, Thy-1+, CD5+, CD3-, B220+, hapten-specific, non-MHC-restricted early-acting cells are required to initiate CS responses by leading to local serotonin release, which allows for extravascular recruitment of the late-acting, alpha beta TCR+, CS effector T cells. This study describes another T cell population that is needed for the adoptive transfer of CS by alpha beta T cells. In vitro treatment of a mixture of CS effector cells with hamster mAb to gamma delta TCR, together with rabbit complement, or by panning on anti-hamster Ig-coated dishes, diminished substantially the subsequent transfer of CS reactivity without affecting either CS-initiating cells, or the later-acting, alpha beta TCR+ CS effector T cells. Immune cells treated with anti-alpha beta TCR mAb, or recovered as adherent cells from petri dishes after anti-gamma delta TCR panning (i.e., gamma delta TCR-enriched cells), reconstituted the ability of anti-gamma delta TCR-treated immune cells (i.e., alpha beta TCR-enriched cells) to transfer 24-h CS responsiveness. The phenotype of the gamma delta T cells that assisted CS effector alpha beta T cells was: CD3+, CD4-, and CD8+. The gamma delta T cells that assisted alpha beta T cells were not Ag-specific since anti-alpha beta-TCR-treated cells (gamma delta T-enriched) from picryl chloride immunized donors aided alpha beta T cells (anti-gamma delta TCR-treated) from oxazolone-immunized donors, and conversely gamma delta T cells from oxazolone-immunized donors aided alpha beta T cells from picryl chloride immunized donors. Furthermore, the CS-regulating gamma delta T cells were not MHC-restricted because gamma delta T cells from H2d or H2b donors could assist alpha beta T cells from H2k donors. It was concluded that a regulatory population of non-Ag specific, non-MHC-restricted gamma delta T cells was needed to assist immune effector, Ag/MHC-specific alpha beta T cells in the adoptive transfer of CS.

Animals↗

PubMed1992

Regulation of contact sensitivity reaction: contrasuppressor T cells and contrasuppressor factor downregulate efferent T suppressor cells.

Contact sensitivity (CS) reaction mediated by CD 4+8- Th 1 cells is under the control of several antigen-specific regulatory lymphocytes. Reaction is downregulated at the induction stage by T afferent suppressor T cells (Ts-aff) that prevent immunization and at the effector stage by efferent T suppressor cells (Ts-eff) that made immune Th 1 cells inoperative. Both suppressor cells are CD 4-8+ Th 1 effector cells and are protected against the suppressive action of Ts-eff cells by CD 4+8- contrasuppressor T cells (Tcs). As has been already shown there are also regulatory interactions between regulatory cells themselves and Ts-aff cells in addition to their effect on precursors of Th 1 cells, also preventing the induction of Ts-eff cells. The present experiments extend these findings and demonstrate that Ts-eff cells are also under negative control of Tcs lymphocytes. Likewise, antigen-specific factor produced by contrasuppressor T-T cell hybridoma, used in lieu of Tcs cells, impedes the activation of Ts-eff cells. In both cases regulation is aimed at the precursors of Ts-eff cells. Our experiments demonstrate that the outcome of immunization is dependent not only on the balance between immune cells and regulatory cells, but also on interactions between regulatory cells themselves.

Animals↗

PubMed1992

Immunological signals which control T cell responses.

A number of identifiable immunological parameters can influence the elicitation and regulation of antigen-specific inflammatory responses to immunogenic epitopes. Injection of antigen in vivo can lead to the activation of type IV hypersensitivity responses, or to the induction of immunological tolerance to that antigen. We have used the hapten trinitrophenol as a model system for studying the factors which influence the generation and regulation of hypersensitivity responses to immunogenic epitopes in vivo. The generation of hypersensitivity or tolerance to trinitrophenyl depends on a number of immunological factors, including the form of the antigen, the route of immunization, and the presence of immune complexes of antibody and antigen on the surface of the antigen-presenting cell. Immunization with trinitrophenyl resulting in unresponsiveness can be the result of either the inability to prime inflammatory cells in vivo or the induction of suppressor T cells.

Animals↗

PubMed1991

Initiation of delayed-type hypersensitivity by low doses of monoclonal IgE antibody. Mediation by serotonin and inhibition by histamine.

Elicitation of delayed-type hypersensitivity (DTH) responses by DTH effector T cells requires a prior phase of DTH initiation. This consists of an immediate hypersensitivity-like response mediated by Ag-specific DTH-initiating factors that are analogous to IgE antibodies in that they sensitize tissue mast cells for release of the vasoactive amine serotonin (5-HT). Experiments were conducted to determine whether IgE mAb injected i.v., or 5-HT injected locally, could initiate DTH. It was found that small doses of IgE (1 microgram/mouse), or of 5-HT (50 to 500 ng locally), which mediated small immediate responses, were optimal for DTH initiation. Even lower doses of IgE (10 ng/mouse), or of 5-HT (5 ng locally), which did not mediate macroscopically measurable immediate responses, were capable of DTH initiation. Higher doses of IgE (10 to 100 micrograms/mouse), which mediated large immediate responses, were not able to initiate DTH. A similar dose response for DTH initiation was found with IgG1 mAb, which is another mast cell-sensitizing isotype of Ig. The inability of high doses of IgE or IgG1 to mediate DTH initiation was probably caused by local release of large inhibitory amounts of histamine, because systemic treatment with the histamine-2 receptor antagonist cimetidine allowed high doses of IgE to initiate DTH. Thus, IgE and IgG1 antibodies could initiate DTH via release of small amounts of 5-HT, but simultaneous release of large amounts of histamine were inhibitory, probably via an effect on histamine-2 receptors of recruited T cells. We concluded the following: 1) IgE or IgG1 antibodies can initiate DTH; 2) DTH initiation need not be associated with macroscopically detectable early responses; 3) mast cell release of 5-HT acts positively whereas release of histamine acts negatively in murine DTH; 4) Ag-specific factors are not the only mechanism of DTH initiation.

Animals↗

PubMed1991

Delayed-type hypersensitivity initiation by early-acting cells that are antigen mismatched or MHC incompatible with late-acting, delayed-type hypersensitivity effector T cells.

The elicitation of delayed-type hypersensitivity (DTH) responses in mice is mediated by the sequential activities of two different Ag-specific, Thy-1+ cells. A required early phase of elicitation is due to DTH-initiating Thy-1+ cells that are CD3- and sIg- and produce Ag-specific factors that act like IgE antibodies in that they sensitize the tissues, so that after local challenge with Ag there is release of the vasoactive amine serotonin. Released serotonin locally recruits and activates CD4+ Th-1 classical DTH effector T cells that secrete lymphokines that attract and activate a nonspecific perivascular infiltrate of circulating, bone marrow-derived leukocytes. The current study used isolated subpopulations of DTH-initiating and DTH-effector T cells to determine whether the two phases of the elicitation of DTH were entirely separate. The contact sensitivity model of DTH was used. Early-acting DTH-initiating cells, and late-acting DTH-effector T cells were either from oxazolone (OX)-immune or picryl chloride (PCl)-immune CBA or BALB/c donors and were transferred to CBA or BALB/c recipients. The results showed that DTH-initiation could be mediated by polyclonal DTH-initiating cells that were Ag mismatched or MHC incompatible with late-acting DTH effector T cells. In fact DTH-initiating cells could be both Ag mismatched and MHC incompatible with late-acting T cells. In addition, potential interactions between different cell populations were ruled out by showing that DTH-initiation could be mediated by a DTH-initiating clone that was Ag or MHC mismatched with the late-acting DTH-effector T cells. Thus, the OX-specific BALB/c clone could initiate DTH for PCl-specific CBA cells in CBA recipients if the recipients were challenged with both OX and PCl, but not when they were challenged with OX or PCl alone. We suggest, at least for the elicitation of DTH reactions in mice, that a more comprehensive description of these responses should accommodate the fact that there are early and late phase responses that each begin with Ag specificity and end with non-specific humoral factors. Inasmuch as the two Thy-1+ cells of DTH can be of different Ag specificity, this suggests that some forms of delayed and chronic inflammation, might be initiated by an immediate hypersensitivity-like immune reactivity to one set of Ag, and could be prolonged and perpetuated by delayed reactivity to another set of Ag.

Animals↗

PubMed1991

Regulatory responses in contact sensitivity: afferent suppressor T cells inhibit the activation of efferent suppressor T cells.

Two types of suppressor cells regulate the contact sensitivity (CS) response to picryl chloride (PCL). Afferent suppressor T cells (Ts-aff) inhibit the generation of CS responses to PCL, while efferent suppressor T cells (Ts-eff) inhibit the activity of Th 1 cells that mediate CS reaction. Intravenous injection of mice with TNP-substituted peritoneal exudate cells (TNP-PEC) induces Ts-eff cells that block the adoptive transfer of contact sensitivity. The induction of Ts-eff cells is prevented by the presence of Ts-aff cells, which in turn are induced by the injection of TNP-PEC coupled with antibodies of the IgG2a and IgG2b isotype (TNP-PEC-Ab). If an animal is injected with TNP-PEC prior to or simultaneously with TNP-PEC-Ab, it generates only Ts-aff cells, while if it is injected with TNP-PEC alone or TNP-PEC prior to TNP-PEC-Ab, it generates Ts-eff cells. Ts-aff cells effect only the generation of Ts-eff cells, as the addition of Ts-eff cells to assays for Ts-eff cells has no inhibitory effect on the suppressive effects of Ts-eff cells in adoptive transfer. Our experiments show that Ts-aff cells induced by TNP-PEC-Ab are phenotypically either Lyt 1+2- or Lyt 1-2+, but only the latter inhibit the generation of Ts-eff cells in vivo. The Ts-aff cells that inhibit Ts-eff activity adhere to the lectin Vicia villosa (VV), while Ts-eff cells are VV nonadherent. In addition, Ts-aff cells can prevent the generation of Ts-eff to linked haptens presented on the same PEC. It appears that a cascade of Ts cell interactions are involved in the regulation of CS responses.

Animals↗

PubMed1991

Serotonin initiation of delayed-type hypersensitivity: mediation by a primitive Thy-1+ antigen-specific clone or by specific monoclonal IgE antibody.

Elicitation of delayed-type hypersensitivity (DTH) responses is due to the required sequential action of two different antigen (Ag)-specific Thy-1+ cells: early acting, DTH-initiating cells and locally recruited CD4+, alpha beta-TCR+, DTH effector T cells. DTH-initiating cells have an unusual phenotype for Ag-specific cells (Thy-1+, CD5+, CD4-, CD8-, CD3-, sIg-, B220+ (CD45RA+), Mac 1+, IL-2R- and IL-3R+) and act by producing Ag-specific non-IgE factors that sensitize mast cells for release of the vasoactive amine serotonin (5HT) at the local site of elicitation of DTH by challenge. Another mechanism of DTH initiation involves Ag-specific IgE antibodies that also can sensitize mast cells for local serotonin release. Serotonin initiates DTH by activating the local endothelial cells to allow recruitment of DTH effector T cells, and also by activating 5HT-2 receptors on these recruited T cells.

Animals↗

PubMed1990

Suppression and contrasuppression in athymic nude mice: nude mice produce the antigen-specific component of a T suppressor factor that inhibits the late 24-hr phase of DTH but do not generate suppression nor contrasuppression of the early initiating phase of DTH.

Previous studies demonstrated that the initiation of murine delayed-type hypersensitivity (DTH), as exemplified by contact sensitivity induced by picryl chloride (PCI) or oxazolone (OX), is due to antigen-specific, T cell-derived, DTH-initiating factors called, respectively, PCl-F and OX-F. These factors participate in the extravascular recruitment of CD4+, Th-1, DTH effector T cells in the elicitation of DTH. Related factors also participate, together with nonantigen binding factors derived from CD8+ T cells, to constitute an antigen-specific T cell-derived suppressor factor (TsF) that can down regulate the ability of Th-1 effector T cells to mediate DTH. Since it was shown recently that athymic nude mice can make antigen-specific, DTH-initiating T cell factors, the current study tested whether nude mice also could produce the antigen-specific component of the TsF that suppresses DTH effector T cells. We found that antigen-specific factors from nu/nu mice could complement the nonantigen-binding subfactor produced in normal mice to constitute the whole antigen-specific TsF. Additional studies showed that the successful adoptive cell transfer of DTH-initiating T cell activity from nude mice into normal mice required cyclophosphamide treatment of the recipient. In contrast, transfer of DTH-initiating cell activity from nu/+ mice did not require cyclophosphamide treatment of the recipients. We hypothesized that nude mice lacked contrasuppressor cells. Although nude mice were able to manifest the early, initiating phase of DTH, we found that there was no suppression of early DTH-initiating T cells in nude mice, compared to nu/+. Therefore the production of DTH-initiating T cell factor could be boosted in nude mice. The ability to boost DTH-initiating cells in nude mice should facilitate the development of cell lines and clones with the ability to initiate DTH.

Animals↗