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V Holford-Strevens

Publications and source records attributed to V Holford-Strevens.

At least 19 recordsLinked to original sources
PubMed1993

Antigen-specific suppressor factors of noncytotoxic CD8+ suppressor T cells downregulate antibody responses also to unrelated antigens when the latter are presented as covalently linked adducts with the specific antigen.

We had previously shown (i) that conjugates of a given antigen A (AgA) and monomethoxypolyethylene glycol (mPEG) induced AgA-specific tolerance in mice which was mediated by polyclonal CD8+ suppressor T (Ts) cells, as well as by soluble factor(s) of these cells (TsF), and (ii) that clones of nonhybridized CD8+ Ts cells could be derived from the above single cells, and monoclonal AgA-specific TsF could be released from these cloned cells. In the present study, we demonstrate that mice pretolerized by injection of AgA(mPEG)n are also unresponsive to an unrelated antigen B (AgB), or to its haptenated derivative AgB-Hpn, when AgB or AgB-Hpn is injected in the form of a covalent adduct with AgA, i.e., AgA-AgB or AgA-AgB-Hpn, but not when it is injected as a mixture with AgA; in this study human (myeloma) IgG (HIgG) served as AgA, and ovalbumin (OVA) or OVA-DNP3 served as AgB or AgB-Hpn. Moreover, this phenomenon was reproduced in vitro; i.e., Ts cells of mice tolerized with HIgG(mPEG)30, or the soluble monoclonal TsF of cloned Ts cells, exerted their associative suppressive effector function--in the obligatory presence of CD8+ T cells of syngeneic naive mice (Tn cells)--on antibody (Ab) formation to an Hp (DNP), when the Hp was present as a covalent adduct linked either directly to HIgG (e.g., HIgG-DNP7) or indirectly via OVA (as in HIgG-OVA-DNP3); however, no suppression of the anti-DNP Ab response was observed when OVA-DNP3 was present as a mixture with HIgG. Furthermore, it was established that the accessory cells involved in processing the specific Ag in the presence of the Ts cells were also downregulated, as reflected by their reduced capacity for presentation of the Ag to HIgG-specific helper T (Th) cells in proliferation assays. All these results demonstrate that (i) the phenomenon of linked immunological suppression may involve the downregulation of Th cells which recognize, concomitantly with the Ts cell, the appropriate epitopes of AgA and AgB on the same Ac cell, (ii) the downregulation of these Th cells may be a consequence of the downregulation of Ac cells by Ts cells interacting with the appropriate epitope(s) present on the Ac cells, and (iii) most remarkably the CD8+ Ts cells could be substituted by Tn cells "armed" with the specific monoclonal TsF.

Animals↗
PubMed1991

Downregulation of helper T cells by an antigen-specific monoclonal Ts factor.

The findings of previous studies in this laboratory demonstrating that conjugates of human monoclonal (myeloma) IgG (HIgG) and monomethoxypolyethylene glycol (mPEG) were able to induce in mice antigen-specific tolerance and CD8+ suppressor T (Ts) cells were confirmed in the present study. An extract (TsF) of a nonhybridized clone of Ts cells (viz., clone 23.32), which had been derived from spleen cells of mice tolerized with HIgG(mPEG)26, was shown to possess antigen-specific suppressive activity. This monoclonal TsF was able to specifically suppress in vitro antibody formation only if it was present from the beginning of the culture. From the results of the cellular dissection of the system used it was concluded that (i) the TsF had no effect on fully differentiated primed B cells or plasma cells, and (ii) the TsF inactivated carrier-primed Th cells when the culture contained concomitantly naive CD8+ T cells, accessory cells, and antigen. These data support the view that the monoclonal TsF exerted its downregulating effect on Th cells only if it could first interact with a CD8+ T cell, in the presence of accessory cells and antigen.

Animals↗
PubMed1990

Cloned suppressor T cells derived from mice tolerized with conjugates of antigen and monomethoxypolyethylene glycol. Relationship between monoclonal T suppressor factor and the T cell receptor.

Cloned Ts cells specific for the Ag, human monoclonal (myeloma) IgG, were derived from spleen cells of mice that had been immunosuppressed by treatment with a tolerogenic conjugate of HIgG and monomethoxypolyethylene glycol. The cloned Ts cells (clone 23.32) suppressed in vitro antibody responses in an Ag-specific and MHC-restricted manner. By FMF with appropriate antibody reagents, these cells were shown to be Thy-1+, CD4-, CD5-, and CD8+ and to express CD3 and the alpha beta-TCR. These results are consistent with the view that Ts cells use Ag recognition structures similar to those reported for Th cells and CTL. A soluble factor (TsF) extracted from the cloned Ts cells also suppressed in vitro antibody responses in an Ag-specific and H-2Kd-restricted manner, i.e., restricted to MHC class I molecules. The suppressive activity of this TsF could be abrogated by addition of mAb H28-710 that reacts with a determinant on the alpha-chain of TCR. Moreover, the TsF bound to and could be recovered from an immunosorbent consisting of the anti-alpha-TCR mAb H28-710 coupled to Sepharose 4B. In contrast, the TsF was not bound by immunosorbents consisting of mAb to the beta-chain of TCR (H57-597) or to V beta 8 (F23.1). It was, therefore, concluded that the TsF of clone 23.32 is serologically related to the alpha-chain of the TCR; however, it is not identical to TCR, because it lacks the determinants expressed on the TCR beta-chain that are recognized by the two anti-beta mAbs used in this study.

Animals↗
PubMed1989

Down-regulation of secondary in vitro antibody responses by suppressor T cells of mice treated with a tolerogenic conjugate of ovalbumin and monomethoxypolyethylene glycol, OVA(mPEG)13.

In previous studies from this laboratory it was shown that OVA(mPEG)n conjugates induced: (i) tolerance in mice with respect to IgG and IgE antibody responses to dinitrophenylated OVA (DNP-OVA); and (ii) OVA-specific suppressor T (Ts) cells which could down-regulate a primary immune response in vivo. For the present study, we have developed an in vitro culture system for assessing the activity of Ts cells of mice tolerized by an OVA(mPEG)13 conjugate. Spleen cells from mice which had been primed with DNP4-OVA in Al(OH)3 gel were cultured with DNP4-OVA to induce a secondary antibody response in vitro. After 6 days, cells secreting anti-DNP antibodies of the IgG1 class were enumerated by an immunoenzymatic plaque-forming cell assay. Addition to the culture of T cells from mice treated with 3 i.p. injections of 500 micrograms of OVA(mPEG)13 resulted in a 29-61% reduction in the number of IgG1 anti-DNP antibody-forming cells, in comparison with the effect of T cells from mice treated with PBS. It was concluded that this tolerogenic conjugate induced splenic Ts cells which were capable of suppressing secondary in vitro anti-DNP responses.

Animals↗
PubMed1988

Suppression of the murine anti-trimellityl (TM) IgE response: induction of B cell tolerance by conjugates of TM and polyvinyl alcohol.

It was previously shown that administration of conjugates of trimellitic anhydride with polyvinyl alcohol (TM-PVA) could suppress the IgE anti-TM immune response of mice sensitized with a TM-ovalbumin conjugate. In the present study, the existence of TM-specific B cell tolerance was shown by cell transfer experiments in which splenic B cells from mice treated with TM-PVA failed to interact with either the helper T (Th) cells of carrier primed recipients or with Th cells derived from carrier-primed donors. In contrast to previous findings from this laboratory indicating that tolerogenic conjugates of PVA and the 2,4-dinitrophenyl group led to both B cell tolerance and activation of suppressor T (Ts) cells, no evidence was obtained for the induction of Ts cells by TM-PVA. Thus, the induction of demonstrable Ts cells by hapten-PVA conjugates may depend on some property conferred by the haptenic group.

Animals↗
PubMed1987

Tolerance induction in mice by conjugates of monoclonal immunoglobulins and monomethoxypolyethylene glycol. Transfer of tolerance by T cells and by T cell extracts.

The specific tolerance induced in mice by conjugates of human monoclonal IgG (HIgG) with monomethoxypolyethylene glycol (mPEG) was transferred to normal mice by spleen cells or a surface immunoglobulin negative (sIg-) Lyt-2+ subpopulation of these cells. Although transferable tolerance was demonstrable 6 to 14 days after treatment of the cell donors with tolerogen, the state of tolerance persisted in the treated mice for at least 43 days. Moreover, an extract prepared by freezing and thawing of the sIg- spleen cells obtained from mice 6 days after treatment with HIgG(mPEG)20 was capable of reducing (greater than 85%) the immune response of normal mice to heat aggregated HIgG. On the basis of these results, it is suggested that similar tolerogenic mPEG derivatives of xenogeneic monoclonal immunoglobulins (XIg) may prove to be useful therapeutic agents in man when administered before treatment with the unmodified XIg.

Animals↗
PubMed1987

Induction of in vivo helper activity for murine antibody responses by macrophages pulsed with ovalbumin-monomethoxypolyethylene glycol (OA-mPEG) conjugates.

Conjugates of protein antigens with an optimal number of monomethoxypolyethylene glycol (mPEG) chains of an appropriate molecular weight had been shown to suppress murine IgE responses to the unmodified antigen. To investigate the possibility that the tolerogenic capacity of these mPEG conjugates is attributable to a defect in macrophage (M phi) presentation of their antigenic determinants, the activity of ovalbumin (OA)-mPEG conjugates when pulsed onto mouse peritoneal adherent cells (M phi) was compared in this study with their activity in solution. Surprisingly, in contrast to the suppressogenic capacity of mPEG conjugates in solution, the OA-mPEG pulsed M phi appeared to exert a helper effect when injected intraperitoneally (ip), i.e., after subsequent immunization with dinitrophenylated OA (DNP3-OA) in Al(OH)3, the mice showed accelerated IgE and IgG1 antibody responses to OA and DNP. However, when M phi were exposed to limiting concentrations of OA or OA-mPEG, markedly higher concentrations of OA-mPEG were required to yield pulsed M phi, exerting a significant helper effect. It was concluded that although M phi were capable of presenting the OA determinants of OA-mPEG conjugates to helper T (Th) cells, the preparations of modified antigen were presented less effectively than native OA.

Animals↗
PubMed1987

Tolerogenic polyethylene glycol derivatives of xenogeneic monoclonal immunoglobulins.

It is becoming apparent that the effectiveness of xenogeneic monoclonal antibodies (XIg), which are increasingly used for diverse therapeutic purposes in man, may be counteracted by their inherent immunogenicity. Since conjugates of proteins with monomethoxypolyethylene glycol (mPEG) have proved to be effective tolerogens in other systems, we have used an experimental model in mice to explore the tolerogenicity of mPEG conjugates of a human monoclonal IgG (HIgG), i.e. a myeloma protein. Administration of these conjugates prior to immunization with heat aggregated HIgG (ha-HIgG) resulted in specific tolerance, as manifested by a marked reduction in the level of antibodies to HIgG, which was related to the degree of conjugation and the dose of conjugate administered. Thus, administration of HIgG(mPEG)20 6 to 43 days prior to immunization with ha-HIgG resulted in an inhibition of anti-HIgG antibody formation of the order of 85-90%, in relation to the titres of mice receiving PBS in lieu of HIgG(mPEG)20; these results hold the promise that mPEG conjugates of XIg may prove therapeutically useful in man in relation to organ transplantation, localization of tumours by immuno-imaging and tumour destruction by immunotoxins.

Animals↗
PubMed1986

The influence of antibody affinity on the radioallergosorbent test (RAST) and in vitro histamine release. Studies with hapten-specific monoclonal IgE antibodies.

Four murine monoclonal IgE antibodies specific for the hapten, 4-hydroxy-3-nitrophenylacetyl (NP), had been previously found to be heteroclitic in nature in that they bound the crossreacting hapten, 4-hydroxy-3-iodo-5-nitrophenylacetyl (NIP), with greater affinity than NP. The influence of antibody affinity on the results of two commonly used assays for IgE, namely the radioallergosorbent test (RAST) and histamine release from rat peritoneal mast cells, was studied using these antibodies. In general, in agreement with previous reports, it was found that affinity influences both RAST and histamine release; however, the affinity constants deduced from equilibrium dialysis measurements for the reactions with monovalent haptens were not directly related to the activities of the antibodies as reflected in assays using multivalent hapten protein conjugates.

Animals↗
PubMed1986

Induction of histamine release in vitro from rat peritoneal mast cells by extracts of grain dust.

The ability of extracts of grain dust and wheat to induce histamine release from rat peritoneal cells was investigated. Some grain dusts, with a high endotoxin content, were found to produce cytotoxic histamine release. Extract of wheat dust, with a low endotoxin release, produced noncytotoxic histamine release from peritoneal cells but not from purified mast cells. This reaction was dependent on the presence of phosphatidyl serine. The agent did not appear to be a lectin because histamine release was not enhanced by passive sensitization of mast cells with IgE. The activity occurred only over a narrow range of concentrations of the extract of wheat. The cause was unclear.

Animals↗
PubMed1986

Acute symptoms following exposure to grain dust in farming.

History of acute symptoms (cough, wheezing, shortness of breath, fever, stuffy nose, and skin itching/rash) following exposure to grain dust was obtained from 661 male and 535 female current and former farmers. These symptoms were relatively common: 60% of male and 25% of female farmers reported at least one such symptom on exposure to grain dust. Association of cough, wheezing, shortness of breath, and stuffy nose with skin reactivity and capacity to form IgE is consistent with an allergic nature of these symptoms. Barley and oats dust were perceived as dust most often producing symptoms. On the other hand, grain fever showed a different pattern, i.e., it was not associated with either skin reactivity or total IgE. Smoking might modify the susceptibility to react to grain dust with symptoms. Only those who reported wheezing on exposure to grain dust may have an increased risk to develop chronic airflow obstruction.

Adult↗
PubMed1984

Desensitization of rat mast cells: studies of some effects of anti-allergic drugs.

Peritoneal mast cells from rats immunized with dinitrophenylated ovalbumin (DNP-OA) or normal cells passively sensitized with mouse anti-DNP-OA were incubated in vitro with DNP-bovine serum albumin in the absence of Ca++. This procedure induced desensitization of the cells, such that histamine release was inhibited on subsequent challenge with OA, in the presence of Ca++. The phenomenon of desensitization is supposed to involve early stages in the histamine release process and, thus, two anti-allergic drugs, disodium cromoglycate and doxantrazole, which inhibit an early event(s), were added with the Ca++ -free antigen to investigate whether they had any effect on desensitization. The inhibition of final histamine release caused by each drug and that due to desensitization were approximately additive. It was concluded that the drugs did not influence desensitization of rat mast cells. Thus, their activity was consistent with an effect on an event in the histamine release process, occurring after the generation of the activated stage believed to be responsible for desensitization.

Animals↗
PubMed1984

Serum total immunoglobulin E levels in Canadian adults.

A history of respiratory and allergic disorders was obtained in a white, rural population with ages 20 to 65 yr. Allergy skin testing was performed, and total IgE was measured by PRIST method. One thousand eight hundred and fourteen subjects were studied. Those subjects with positive allergic skin reactions and a history of allergic disorders and smoking were excluded to provide a reference group to derive "normal" values of total IgE. The mean level of the total IgE of this reference group was 12.1 U/ml. The upper limit of the normal range of total IgE levels was estimated at 87.3 U/ml. IgE levels did not differ between the sexes or with age in our adult population.

Adult↗
PubMed1984

Suppression of the anti-trimellityl (TM) IgE response in mice by conjugates of TM with polyvinyl alcohol.

The i.p. injection of 1 microgram of TM3-OA or TM9-OA with 1 mg of A1(OH)3 into B6D2F1 mice elicited the production of antibodies of the IgE and other classes to the trimellityl (TM) group and ovalbumin (OA). The induction of anti-TM antibodies belonging to the IgE and other immunoglobulin classes was specifically suppressed by the administration of tolerogenic conjugates prepared by coupling trimellitic anhydride (TMA) to the hydrophilic non-immunogenic polymer, polyvinyl alcohol (PVA), prior to immunization with TM-OA conjugates. More importantly, established anti-TM responses were also suppressed by these TM-PVA conjugates. By contrast, however, treatment with TM-PVA conjugates did not affect either the primary or the established anti-OA antibody response. The tolerogenic effects of the PVA conjugates were dose-dependent and appeared also to be dependent on the epitope density. Treatment with these conjugates also prevented immunized mice from showing any symptoms of systemic anaphylaxis on challenge with polyvalent TM-protein conjugates. These findings indicate that these conjugates may have the potential of useful therapeutic agents for the treatment of TMA-induced pulmonary hypersensitivity diseases.

Anaphylaxis↗
PubMed1983

Tumor-reactive IgE antibodies in plasma of patients with gastrointestinal carcinomas.

A total of 208 plasma samples from 115 patients with gastrointestinal carcinomas and nine patients with other intestinal disease were examined for the presence of IgE tumor antibodies by a solid-phase radioimmunoassay. Approximately one-third of the patients gave significant reactions with gastrointestinal carcinoma extracts compared with normal tissue extracts. Absorption with tumor and normal tissue extracts, with type AB human red cells, and with CEA indicated tumor specificity in some of the samples so examined. None of the 50 serum samples tested from normal blood donors contained tumor-specific IgE. IgE tumor antibodies decreased or completely disappeared in the majority of patients 8-13 days after surgical treatment.

Antibodies, Neoplasm↗
PubMed1983

Sensitization in a grain handler to the storage mite Lepidoglyphus destructor (Schrank).

Allergy to one of the most common Canadian storage mites. Lepidoglyphus destructor, was demonstrated in a grain worker by immediate skin testing and inhalation challenge. The frequency of sensitization to this mite was found to be 12% in 100 asthmatics by skin testing. In 4% of these asthmatics sensitization to another storage mite, Acarus siro, was found, all of whom were also sensitized to L. destructor and the house dust mite, Dermatophagoides farinae. There was a significantly higher proportion of asthmatics sensitive to the storage mites and to fungi who had a history of exposure to grain compared to those who did not.

Asthma↗