Biomedical subjects

M K Crow

Publications and source records attributed to M K Crow.

At least 55 records · Page 3Linked to original sources

PubMed1989

Presence of a non-HLA B cell antigen in rheumatic fever patients and their families as defined by a monoclonal antibody.

Numerous investigators have suspected that there is a genetic predisposition to rheumatic fever (RF). In this context we have recently produced a series of monoclonal antibodies directed against B cells obtained from RF patients one of which, labeled D8/17, identifies a B cell antigen present in 100% of all RF patients studied. While the highest percentage of positive cells were exhibited by RF probands (33.5% +/- SE), the percentage of cells in unaffected siblings and parents was 14.6 and 13%, respectively. The percentage of positive cells in APSGN probands, unaffected siblings, and parents was 2.96, 3.86, and 2.8%, respectively. A low level of B cells (5-7%) bearing the D8/17 marker was seen in control patients. The segregation pattern of the phenotypes defined by the percentage of D8/17 positive cells within HLA-typed RF families are consistent with an autosomal recessive mode of inheritance not associated with the human MHC system. We postulate that these phenotypes indicate the presence of at least one necessary genetic factor for susceptibility to RF.

Analysis of Variance↗

PubMed1989

Human immunodeficiency virus infection of helper T cell clones. Early proliferative defects despite intact antigen-specific recognition and interleukin 4 secretion.

HIV selectively inhibited the proliferative response of clonal CD4+ T lymphocytes to alloantigen while other alloantigen-dependent responses were unperturbed. Specifically, impaired blastogenesis could be dissociated from alloantigen-specific induction of the B cell activation molecule CD23, IL-4 release, and inositol lipid hydrolysis. In addition, membrane expression of pertinent T cell receptor molecules, including CD2, CD3, and T cell antigen receptor (Ti), remained intact. Using two MHC class II-specific human CD4+ helper T cell clones, the proliferative defect was shown to be an early consequence of HIV infection, occurring within 4 d of viral inoculation and preceding increases in mature virion production. It was generalizable to three distinct methods of T cell activation, all independent of antigen-presenting cells: anti-CD3 mediated cross-linking of the CD3/Ti complex; anti-CD2 and phorbol 12-myristic 13-acetate (PMA); and anti-CD28 plus PMA. These abnormalities were not mitigated by addition of exogenous IL-2, even though expression of the IL-2 receptor (CD25) was unaltered. These studies define a selective blockade in T cell function early after HIV exposure that could serve as a model for certain in vivo manifestations of AIDS.

Acquired Immunodeficiency Syndrome↗

PubMed1989

Biochemical basis of synergy between antigen and T-helper (Th) cell-mediated activation of resting human B cells.

We have utilized CD23 expression as a marker for B cell activation in order to investigate the biochemical basis for synergy between antigen and T helper (Th) cells in the activation of resting human B cells. Our results confirm that while ligation of surface immunoglobulin (sIg) receptors by antigen analogues (e.g., F(ab')2 goat anti-human IgM) does not lead to CD23 expression, this stimulus markedly enhances CD23 expression induced during antigen specific Th-B cell interaction or by rIL-4. Utilizing a panel of monoclonal anti-human IgM antibodies, we observed a positive correlation between the capacity of a particular antibody to synergize with rIL-4 in CD23 expression and with B cell growth factor in B cell proliferation; suggesting that synergy in CD23 expression reflects the transduction of a functionally important signal via the sIg receptor. We next assayed analogues of the "second messenger" molecules, released during inositol lipid hydrolysis, for their capacity to amplify CD23 expression. These studies showed that protein kinase C (PKC) activating phorbol esters and the synthetic diacylgylcerol analogue, DiC8, synergize with either Th cells or rIL-4 in CD23 expression, while under no experimental condition does increasing B cell [Ca2+]i with ionomycin enhance CD23 expression. Taken together, these data suggest that activation of B cell PKC is the crucial biochemical event that primes antigen-activated B cells to respond more vigorously to interaction with Th cells and/or their soluble products.

Antibodies, Monoclonal↗

PubMed1988

Direct human T helper cell-induced B cell activation is not mediated by inositol lipid hydrolysis.

The Ag-specific interaction between cloned allospecific human Th cells and class II MHC determinants on the surface of allogeneic B cells induces a significant fraction of resting B cells to express a B cell specific activation Ag BLAST-2 (CD23). On the other hand, cross-linking of B cell surface Ig R by Ag analogues does not lead to BLAST-2 expression. By utilizing the BLAST-2 induction assay as a positive control for efficient Th-B cell interaction, we have investigated the biochemical basis of human B cell activation mediated by Ag and Th cells. Our data demonstrate that ligands for sIg R, including F(ab')2 goat anti-human IgM and Staphylococcus aureus protein A, stimulate the metabolism of B cell membrane inositol lipids as assessed by: 1) increased [3H]inositol phosphates formation in myo-[3H]inositol-labeled B cells; 2) selective incorporation of [32P]orthophosphate into phosphatidic acid and phosphatidylinositol, but not into phosphatidylethanolamine or phosphatidylcholine; and 3) rapid increase in B cell cytoplasmic ionized Ca2+ concentration ([Ca2+]i). In contrast, direct Th-B cell interaction leads to high intensity BLAST-2 expression on the B cell surface but this response is not mediated by changes in inositol lipid metabolism or [Ca2+]i. Further, Th-B cell interaction does not affect the changes in B cell inositol lipid metabolism or [Ca2+]i triggered by sIg cross-linking. Taken together, our results suggest that Ag and Th cells induce different functional B cell responses by activating distinct second messenger systems within the B cell.

Antigens↗

PubMed1988

Amplification of altered self-reactive cytolytic T lymphocyte responses by cloned, allospecific human Th cells.

The effect of a cloned allospecific human Th cell, termed 86, on the in vitro generation of altered self-reactive cytolytic T lymphocytes (CTL) was investigated. Utilizing the induction of hapten altered self-reactive CTL as a model for virus or tumor-specific cell-mediated immunity, we determined that the presence of small numbers of clone 86 cells markedly amplified the generation of hapten altered self-reactive CTL. The killer cells induced belong to the CD4-, CD8+ subset, are specific for the hapten-modified autologous stimulator cells present in culture, and are MHC class I restricted. The CTL induced under these culture conditions are readily expanded in the presence of IL-2 with maintenance of efficient and specific altered self-killing. Of interest, clone 86 cells preferentially enhance the growth of CD8+ T cells and selectively amplify altered self-cytolysis but not NK cell activity. Although in vitro clone 86 cells mediate help for CTL generation via the production of lymphokines (IL-4 but little IL-2), one can envision immunotherapeutic strategies for human disease that involve the adoptive transfer of Th cells functionally analogous to clone 86.

Antigens, Differentiation, T-Lymphocyte↗

PubMed1986

Direct T helper-B cell interactions induce an early B cell activation antigen.

We have explored the consequences for the B cell of cognate interaction with T cells. Early expression of the B cell-restricted cell surface activation antigen, BLAST-2, has been used as an assay system to measure direct T-B cell collaboration. BLAST-2 is preferentially expressed by allogenic B cells cultured with MHC class II antigen-restricted Th clone cells matched to the DR specificity of the target B cells. B cells cultured with DR-mismatched allospecific Th cells express minimal BLAST-2. Th cell-induced BLAST-2 expression appears to be accessory cell independent and occurs as early as 8 h after initiation of culture, with peak expression at 18 h. Direct T-B cell contact, rather than Th-derived lymphokines, provides the most efficient stimulus for BLAST-2 expression. Crosslinking of sIg on B cells is a poor stimulus for BLAST-2 expression. The BLAST-2 assay permits the evaluation of early events associated with B cell activation through cognate interactions, and may facilitate subsequent studies of the mechanism of B cell differentiation.

Antibodies, Anti-Idiotypic↗

PubMed1986

Antigen-specific, MHC nonrestricted T helper cell-induced B cell activation.

We used a cloned, TNP-specific, MHC-restricted, human Th cell line, E-11, and an assay of cognate Th-B cell interaction, BLAST-2 antigen expression on the B cell surface, to investigate the functional nature of the Th cell antigen receptor. We observed that E-11 induces BLAST-2 expression by resting B cells in a hapten-dependent, hapten-specific, but MHC nonrestricted manner. The implication of these results for the Th cell receptor are discussed.

Antigens, Differentiation, B-Lymphocyte↗

PubMed1986

Human helper-T-cell function does not require T4 antigen expression.

The relationship between immunoregulatory T-cell function and the expression of T-cell subset-specific differentiation antigens was examined using a phenotypically anomalous human T-cell line (TCL), termed H-1. H-1 cells were found to express T11, extremely high levels of T3, but no T4 nor T8 antigen. Despite their lack of T4 antigen expression, H-1 cells could be activated by coculture with pokeweed mitogen (PWM), anti-T3 antibody, or autologous B cells to provide potent help for B-cell differentiation into plaque-forming cells (PFC). In contrast, H-1 cells did not suppress the PFC response triggered by PWM-activated T4+ cells. These results demonstrate that the expression of the T-cell subclass-specific differentiation antigen, T4, is not required for a T cell to become activated and to implement the program for helper function. In addition, enhanced expression of T3 on the T4-, T8-, H-1 cell surface may reflect a compensatory upregulation of the T3/Ti receptor complex on T cells which are deficient in these nonpolymorphic associative recognition structures.

Antigens, Differentiation, T-Lymphocyte↗

PubMed1985

Systemic lupus erythematosus with deficiency of the T4 epitope on T helper/inducer cells.

Three black Jamaicans with systemic lupus erythematosus (SLE) were identified whose T helper/inducer cells lacked the T4 epitope (T4 epitope-deficient phenotype). All three patients had lymphadenopathy as part of their syndromes. The asymptomatic and otherwise healthy T4 epitope-deficient brother of one of these patients also had lymphadenopathy in a distribution identical to that of his sister with SLE. Family studies pointed to an autosomal codominant mode of inheritance not linked to the HLA locus for the T4 epitope phenotype. Cultures of peripheral-blood mononuclear cells revealed impaired B-cell differentiation upon stimulation with pokeweed mitogen in cells originating from the T4 epitope-deficient family members as compared with those originating from their T4 epitope-intermediate relatives. Ratios of T helper/inducer cells to T suppressor/cytotoxic cells, the presence of various autoantibodies, and proliferation in response to mitogens and in the mixed lymphocyte reactions did not correlate with T4 epitope phenotype. We suggest that SLE in association with the T4 epitope-deficient phenotype may represent a unique subset of patients with SLE that has distinct clinical and immunologic properties.

B-Lymphocytes↗

PubMed1985

Activated B lymphocytes: stimulators of an augmented autologous mixed leukocyte reaction.

The characteristics of the non-T cell(s) which stimulate T-lymphocyte proliferation in the autologous mixed leukocyte reaction (AMLR) have been at issue since this in vitro reaction was first described. Dendritic cells have been shown to be the most potent stimulator cells, but B cells, null cells, and macrophages have also been demonstrated to have the capacity to stimulate autologous T-cell proliferation. A cell preparation obtained from human peripheral blood was highly enriched for surface immunoglobulin-positive B cells. These cells were activated by brief culture with various B-cell mitogens and then compared to untreated B cells with regard to stimulatory activity in the AMLR. Mitogen-activated B cells were markedly augmented in their capacity to stimulate autologous T-cell proliferation when compared with untreated B cells. Fractionation of the B-cell preparation into high- and low-density subpopulations demonstrated that the high-density cells, enriched in resting B cells, had minimal stimulatory activity but could be activated to have increased AMLR-stimulatory capacity. Proliferation of the activated B lymphocytes was not required for the generation of the augmented AMLR. Response to both untreated and mitogen-activated B cells was a property of T4-positive T lymphocytes. The increase in stimulatory capacity was associated with a decrease in cell surface immunoglobulin, but no significant alteration in the percentage or fluorescence intensity of anti-Ia staining cells was detected. Activated B cells which are generated in vivo may acquire the capacity to generate T effector cells or factors important in the regulation of B-cell function.

Antibodies, Monoclonal↗

PubMed1985

Anti-immunoglobulin stimulation of human B lymphocytes is inhibited by anti-class II major histocompatibility complex antibodies.

The effect of murine monoclonal antibodies binding monomorphic epitopes of Class II, HLA-DR molecules on responding human B lymphocytes stimulated by anti-immunoglobulin M (IgM) antibodies was studied. Goat F(ab')2 anti-human IgM coupled to Sepharose beads (insoluble), or in solution, was added to macrophage-depleted B cells in culture with, or without, anti-human HLA-DR monoclonal antibodies. The addition of monoclonal anti-HLA-DR antibodies to anti-human IgM-stimulated B lymphocytes inhibited this T-independent B-cell proliferation by 82-94%. The role of Class II, HLA-DR molecules on B cells may therefore exceed that of antigen presentation alone, to include responding B-cell activation induced by anti-immunoglobulin.

Antibodies, Anti-Idiotypic↗

PubMed1985

Purification and in vitro growth of human epidermal basal keratinocytes using a monoclonal antibody.

We have made a new monoclonal antibody, EL-2, and used it with an immunorosetting procedure combined with Ficoll-Hypaque gradient centrifugation to purify and culture basal keratinocytes. Immunofluorescence of cell suspensions and immunoperoxidase staining of tissue sections demonstrate that EL-2 reacts with malignant cell lines, activated lymphocytes and monocytes, and basal keratinocytes. Sequential immunoprecipitation studies demonstrate that monoclonal antibodies EL-2 and 4F2 detect the same membrane protein. However, we have extended previous studies by making the new observation that both EL-2 and 4F2 react with cultured melanocytes. Basal keratinocytes were purified from single-cell epidermal suspensions by incubation with EL-2 followed by rosetting with rabbit antimouse IgG antibodies covalently linked to bovine red blood cells. Rosetting (basal) keratinocytes were separated from EL-2 negative cells by Ficoll gradient centrifugation. We obtained basal keratinocyte populations of greater than 90% purity as assessed by reactivity with EL-2 and another basal keratinocyte-specific monoclonal antibody, HCl. Langerhans cell, fibroblast, and melanocyte contamination was negligible. Cultures of basal keratinocytes were enriched in EL-2-reactive cells throughout the entire 19 days of culture studied. EL-2 is being used to characterize disorders of keratinocyte proliferation; EL-2 reacted with both squamous and basal cell carcinomas. EL-2 stained only the basal layer of lesional skin from patients with psoriasis, pityriasis rubra pilaris, and Darier's disease. Purification of basal keratinocytes will be important in biochemical and functional studies of normal skin and in establishing long-term keratinocyte lines from normal cells.

Antibodies, Monoclonal↗

PubMed1985

Enhancement of the impaired autologous mixed leukocyte reaction in patients with systemic lupus erythematosus.

The cellular basis of the impaired autologous mixed leukocyte reaction (AMLR) in patients with systemic lupus erythematosus (SLE) was investigated. Non-T cells from normal subjects and from SLE patients were fractionated into low and high density subpopulations. SLE patients were found to have an increased proportion of low density to high density non-T cells when compared to normal subjects. Although normal low-density non-T cells were highly enriched in AMLR stimulatory capacity, SLE low-density non-T cells induced minimal proliferation by autologous T cells. Brief incubation of SLE non-T cells with phorbol myristate acetate or formalin-treated Staphylococcus aureus resulted in marked augmentation of the capacity of those non-T cells to stimulate an AMLR, although the magnitude of the activated non-T cell-induced AMLR did not achieve that observed in normal subjects. No significant alterations in the expression of Ia molecules on the surface of the non-T cells were detected after in vitro activation. These experiments support the hypothesis that the impaired capacity of SLE T lymphocytes to proliferate in response to autologous non-T cells may in part represent a failure of SLE non-T cells to present an appropriate stimulus for the generation of a T cell response.

Adult↗

PubMed1985

Cloned allospecific human helper T cell lines induce an MHC-restricted proliferative response by resting B cells.

To analyze helper T (Th) cell-induced B cell proliferation in man, we have cloned allospecific Th cells, grown them as long-term IL 2-dependent T cell lines (TCL), and analyzed their phenotypic and functional properties. The two TCL described in this report, A-7 and A-57, are both composed exclusively of T3+, T4+, T8- T cells blasts. In proliferative assays, with a panel of x-irradiated allogeneic stimulator cells, A-7 was found to proliferate in response to DR3-bearing cells, whereas A-57 responds to DR2-positive stimulators. Both TCL are capable of providing MHC-restricted polyclonal help for allogeneic B cells, as measured in the reverse hemolytic plaque assay. Of greater interest, x-irradiated A-7 and A-57 cells are capable of inducing a proliferative response by allogeneic B cells that is absolutely MHC restricted at the inductive (Th-APC) level. Thus, x-irradiated A-7 cells only trigger proliferation by DR3+ B cells, whereas A-57 cells selectively activate DR2+ B cells. In contrast, after antigen-specific activation, x-irradiated A-7 and A-57 cells can recruit a significant proliferative response by allogeneic B cells bearing "irrelevant" DR antigens. The possibility that Th-induced B cell proliferation may be restricted at the effector (Th-B cell) level was addressed by fractionating B cell populations into "activated" and "resting" subsets by discontinuous Percoll density gradient centrifugation and further purification by employing a monoclonal antibody directed against an antigen expressed on activated B cells (4F2). These studies demonstrate that activated B cells are readily and nonspecifically recruited to proliferate by activated Th cells, whereas optimal proliferative responses by resting B cells require MHC restricted Th-B cell interaction.

Antibodies, Monoclonal↗

PubMed1985

Synergy between B cell differentiation factors and interleukin 2, using a monoclonal system.

By using monoclonal B cell targets, cells derived from patients with chronic lymphocytic leukemia, and B cell differentiation factors (BCDF) derived from monoclonal human T cell hybridomas, we have demonstrated marked synergy for differentiation between interleukin 2 (IL 2) and BCDF. IL 2 alone had no effect on the proliferation of differentiation to immunoglobulin secretion in these cell populations; however, in conjunction with a variety of BCDF, differentiation to plaque-forming cells (PFC) was augmented 10- to 100-fold. There was no increase in proliferation as measured by [3H]thymidine incorporation. These effects could be demonstrated with concentrations of IL 2 as low as 5 U/culture, well within the physiologic range, by using either commercially available or recombinant IL 2. The addition of IL 2 to the B cell and BCDF cultures resulted in almost 100% expression of the IL 2 receptor, Tac, on the surface of these cells, and the augmented PFC response could be inhibited 70 to 80% by the addition of anti-Tac to the culture. Kinetic studies revealed that the addition of IL 2 to the B cell cultures could be delayed for up to 72 hr without a change in the PFC response, suggesting that IL 2 was acting as a secondary or synergistic signal for differentiation. Thus, it appears that IL 2 does have a role in B cell maturation mediated, in part, by IL 2 binding to the IL 2 receptor present on certain B cells.

Antibodies, Monoclonal↗

PubMed1985

Requirements for T cell activation by OKT3 monoclonal antibody: role of modulation of T3 molecules and interleukin 1.

The requirements for activation of human peripheral blood T cells by the mitogenic monoclonal antibody OKT3 were examined. OKT3 binds to a T cell molecule, T3, associated with the T cell antigen receptor and involved in T cell activation. Activation of T cells by OKT3 requires signals provided by accessory cells and is IL 2 dependent. In the presence of accessory cells, OKT3 induces loss of T3 molecules from the cell surface, production of IL 2, expression of IL 2 receptors, and proliferation. Modulation of T3 molecules by OKT3 can be induced in the absence of accessory cells with anti-mouse IgG. These T cells, however, are not induced to express IL 2 receptors or secrete IL 2. The addition of IL 1 induces expression of IL 2 receptors, but does not induce IL 2 secretion or proliferation. Thus, peripheral blood T cells appear to have different requirements for activation compared with antigen-specific T cell clones that can be induced to produce IL 2 when stimulated with OKT3 and IL 1. Expression of IL 2 receptors does not require modulation of T3 molecules, because the binding of OKT3 to T cells in the presence of IL 1 alone is sufficient to induce IL 2 receptor expression. The results suggest that IL 2 secretion depends on cross-linking and modulation of T3 molecules, and additional, as yet undefined, accessory cell signals. The expression of IL 2 receptors and proliferation of T cells can be induced in the absence of these signals when exogenous IL 2 is provided.

Antibodies, Monoclonal↗

PubMed1984

Modulation of mononuclear phagocyte function by intravenous gamma-globulin.

To assess the effects on mononuclear phagocyte function of i.v. gamma-globulin treatment in idiopathic thrombocytopenic purpura, we examined in vivo and in vitro mononuclear phagocyte function in 11 patients before and after therapy. All patients, both splenectomized and non-splenectomized, demonstrated a prolongation of in vivo clearance of autologous IgG-sensitized erythrocytes (p less than 0.01). Concurrent in vitro assessment of blood monocyte function showed decreased IgG-sensitized erythrocyte (EA) rosette formation (mean +/- SD: 31.6% +/- 8.2 vs 24.5% +/- 9.5; p less than 0.03) and decreased affinity of Fc receptor-specific IgG oligomer binding (9.9 +/- 16.3 vs 1.8 +/- 2.1 X 10(8) M-1; p less than 0.008), but no consistent change in the estimate of the maximum number of binding sites. Phagocytosis of two different EA probes was decreased (EhuA:0.49 +/- 0.26 vs 0.25 +/- 0.14 erythrocyte/monocyte/hr; p less than 0.02, EoxA: 1.76 +/- 0.66 vs 1.27 +/- 0.67 erythrocyte/monocyte/hr, p less than 0.05). The change in in vivo mononuclear phagocyte system clearance was significantly correlated with the change in the association constant for oligomer binding (r = 0.98, p less than 0.05). These data demonstrate that i.v. gamma-globulin infusions induce alterations of mononuclear phagocyte function that are not dependent on the presence of autologous serum containing infusate. The change in apparent Fc receptor affinity rather than receptor number may reflect an altered Fc receptor population with different binding properties.

Adolescent↗

PubMed1984

An antigen characteristic of hairy cell leukemia cells is expressed on certain activated B cells.

A murine monoclonal antibody, anti-HC2, which reacts with hairy cell leukemia cells, was used to define the normal cell equivalent for the leukemic hairy cell. This antibody stained the membranes of 2.24% of normal peripheral blood lymphocytes. These cells were more common in T cell-depleted cell populations, and bore membrane immunoglobulin. Some B lymphoblastoid cell lines were also anti-HC2-positive. Examination of normal B cell subpopulations revealed that HC2-positive cells frequently co-express an activation antigen and membrane IgG. Cell populations enriched for HC2-positive cells contained the bulk of PWM-responsive B cells. These data suggest that HC2-bearing B cells are activated B cells. B cell differentiation induced in vitro by PWM with T cell helper factors resulted in an increase in the number of HC2-positive cells at day 4 or 5 of culture. The HC2-positive cells were no longer present at the time of maximal plasma cell differentiation on day 7 of culture. By using B cells from a patient with the hyper-IgM syndrome that are incapable of immunoglobulin heavy chain class switching, it was demonstrated that HC2 expression did not require prior heavy chain switch. The m.w. of the HC2 antigen was 52 to 63 KD. Four bands with different isoelectric points were discerned on two-dimensional analysis. We suggest that hairy cell leukemia represents a malignancy of activated B cells. A unique stage of B cell differentiation is identified by the HC2 activation antigen.

Antibodies, Monoclonal↗