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Biomedical subjects

L Mayer

Publications and source records attributed to L Mayer.

At least 145 records · Page 8Linked to original sources
PubMed1987

Evidence for function of Ia molecules on gut epithelial cells in man.

Using freshly isolated Ia+ gut epithelial cells we have been able to demonstrate that these cells can function as accessory cells in an immune response. The cells can act as stimulators in both autologous and allogeneic MLRs. More importantly, these cells are capable of taking up the soluble antigen, tetanus toxoid, processing it, and presenting it to tetanus-primed T cells. These functions appear to relate to the presence of surface Ia in that a hetero-anti-Ia antibody can block these effects. Noteworthy is the finding that the subpopulation of T cells stimulated when epithelial cells are used as accessory cells is the T8+, 9.3-T cell. These cells function as potent antigen-nonspecific suppressor cells in both MLR, T cell antigen responses, and induction of B cell differentiation by PWM. These findings have significant implications in local gut immune responses and may help explain several poorly characterized phenomena of mucosal immunity.

Adenocarcinoma↗
PubMed1987

Inhibition of T cell-dependent human B cell proliferation and B cell differentiation by polyspecific monomeric IgG.

A commercially available polyspecific, monomeric IgG preparation suitable for intravenous administration (IgSRK; Sandoglobulin) can inhibit pokeweed mitogen (PWM)-induced proliferation of peripheral blood mononuclear cells (PBMC) by a small, but statistically significant, amount compared to control cultures. Such inhibition could not be demonstrated when PBMC were stimulated with the T cell mitogen phytohaemagglutinin. Surface phenotype analysis of the PWM-stimulated cells indicated that in IgSRK-containing cultures, the proportion of B cells was decreased and the proportion of T cells was increased compared to control cultures. This alteration in T:B ratio was not due to antigenic modulation of B or T cell markers from their surfaces. In addition, IgSRK inhibited the proliferation of T cell-depleted PBMC cultures stimulated by B cell proliferation factors (BCPF) but not by fixed protein A-bearing Staphylococcus aureus strain Cowan I. The capacity to inhibit B cell proliferation was independent of and distinct from its capacity to inhibit B cell differentiation, since IgSRK inhibited the differentiation of a B cell differentiation factor (BCDF)-sensitive line by BCDF (which contains no BCPF activity). IgSRK inhibited PWM-induced generation of cytoplasmic Ig+ cells but had no effect on Ig secretion from mature Ig-secreting cells. Taken together, these findings suggest that IgSRK (which contains the IgG fraction from pooled plasma from 2,000 healthy donors) can inhibit T cell-dependent or T cell factor-dependent B cell proliferation and B cell differentiation.

B-Lymphocytes↗
PubMed1986

Terminal maturation of resting B cells by proliferation-independent B cells differentiation factors.

Using response to four different BCDF preparations as a model of B cell maturation, we have shown that induction of B cell proliferation abrogates terminal maturation of these cells. In fact, response to some BCDFs can occur in the presence of inhibitors of DNA replication, suggesting that there are proliferation-independent as well as proliferation-dependent BCDFs. These findings cannot be explained by changes in the kinetics of the BCDF response, nor can they be reversed by repletion of media or changing cell densities. Proliferation-independent BCDFs appear to exert their effects on dense, resting 4F2- B cells rather than more activated B cells. This is in contrast to B cell differentiation signals of IL-2 alone or SAC and IL-2 in concert. These data suggest that the current models of B cell activation and maturation may require some reorganization, relegating the proliferative phase of B cell maturation to a lesser role. In addition, evidence is provided for the fact that the resting B cell may have the full complement of receptors for BCDF as well as BCGF and BCPF and may help account for the inherent nonspecificity of the immune response.

Antibody Formation↗
PubMed1986

Molecular cloning of pertussis toxin genes.

We have cloned a 4.5 kb EcoRI/BamHI DNA fragment from Bordetella pertussis which contains at least two genes responsible for expression of pertussis toxin. The S4 subunit of the toxin was isolated by high pressure liquid chromatography and the NH2-terminal amino acid sequence determined. Using a mixed synthetic oligonucleotide probe designed by reverse translation of a portion of the protein sequence, a cloned DNA fragment was identified which contains the coding information for at least the S4 structural subunit of the toxin. Sequence analyses indicate that the mature protein is derived by proteolytic cleavage of a precursor molecule. Southern blot analyses of Tn5-induced B. pertussis toxin-deficient mutants show that the Tn5 DNA is inserted 1.3 kb downstream from the S4 subunit gene. This second gene could code for another subunit required for assembly of the mature toxin or a non-structural transport protein, possibly in the same polycistronic operon. The molecular cloning of pertussis toxin genes provides the basis for development of a safer recombinant "new generation" vaccine for whooping cough.

Amino Acid Sequence↗
PubMed1986

Evidence for a defect in "switch" T cells in patients with immunodeficiency and hyperimmunoglobulinemia M.

Immunodeficiency with hyperimmunoglobulinemia M is a syndrome characterized by normal to elevated serum levels of IgM and low levels or absence of IgG and IgA. The defect in this syndrome is thought to reside within the B lymphocyte, which may be unable to undergo a "switch" in immunoglobulin class from IgM to IgG or IgA. To address this question more directly, we cultured B cells from nine patients with this syndrome with pokeweed mitogen and either "switch" T cells or normal control T cells. In cultures with normal T cells, only IgM was secreted, whereas in cultures with switch T cells, IgG as well as IgM, or IgM, IgG, and IgA were secreted. Furthermore, analysis of the immunoglobulin heavy-chain genes in these B cells by means of genetic probes of constant and switch regions revealed normal gene patterns. These data suggest that B cells from patients with hyperimmunoglobulinemia M may not be abnormal, as previously proposed, and that, at least in some patients with this syndrome, a defect in switch T cells may be pathogenic.

Adolescent↗
PubMed1986

Modulation of the immune response by immunoglobulin for intravenous use. II. Inhibitory effects of sera from treated patients.

Sera were collected from patients with common varied immunodeficiency (CVI) prior to and following intravenous gamma-globulin (IVGG) infusion. Cultures of pokeweed mitogen (PWM)-stimulated peripheral blood mononuclear cells from normal donors in medium containing post-IVGG infusion sera generated significantly fewer plaque-forming cells (PFC) than those cultures in medium containing the corresponding pre-IVGG infusion sera. However, preinfusion CVI sera were found to be similar to normal sera in their capacities to support PWM-induced PFC generation, despite the disparity in Ig levels between the two groups of sera. Furthermore, serum collected from a CVI patient 24 hr or more after IVGG infusion no longer possessed the same inhibitory capacity as serum collected 10 min after IVGG infusion despite elevated IgG levels compared to baseline. These studies suggest that IVGG infusion may induce an immunosuppressive effect which is transient in nature, raising the possibility of in vivo counterbalancing homeostatic mechanisms responding to this immune perturbation.

Antibody-Producing Cells↗
PubMed1986

Stability of lactate dehydrogenase at different storage temperatures.

The effect of storing human serum, cord blood serum or heparinized plasma at 25 degrees C, 4 degrees C & -20 degrees C on the activity and isoenzyme distribution of lactate dehydrogenase (LD) was studied. Cellulose acetate and agarose electrophoresis, as well as an immunochemical inhibition technique, were used for isoenzyme quantification. In contrast to previous reports, cryo-instability was found only in specimens stored at 4 degrees C. Serum specimens stored at 25 degrees C and -20 degrees C retained 74% and 87% of total activity after 45 days of storage. LD-1 was stable at all three temperatures, with a maximum loss of 10%. LD-2, LD-3, LD-4, & LD-5 were most labile at 4 degrees C. Specimens that are to be analyzed for total LD or LD isoenzymes should be stored frozen or, if necessary, at room temperature, but not in a refrigerator. Thus, separate storage of specimens for cardiac isoenzymes (LD & creatine kinase) is not necessary. This may eliminate a possible source of falsely elevated LD-1/LD-2 ratios, as well as reducing the labor factor and the corresponding cost of cardiac isoenzyme determinations.

Binding Sites, Antibody↗
PubMed1985

Rapid generation of human T cell hybridomas.

Using the concept of a selectable surface marker we have generated screenable human T cell hybridomas within 4-7 days of fusion. OKT4+ T cell blasts were fused with MOLT4, an OKT4- T cell line, and OKT4+ fusion products were obtained by indirect rosetting technique. Supernatants of this heterogeneous population of hybrids were screened and those with activities of interest were subjected to cloning on soft agar and re-screening to dissect out various activities. Fusion efficiency, by staining, ranges from 6 to 80% depending on the state of activation of the T blasts and the growth phase of the MOLT4 line. This method allows for immortalization of T cell subpopulations, clones and malignant cells to study factor production and potentially messenger RNA for these factors. Additionally selectable surface markers may be used in human B cell and rodent:human fusions, avoiding the innate toxicity of various selection media.

Antigens, Surface↗
PubMed1985

Human malignant T cells capable of inducing an immunoglobulin class switch.

Evidence is presented for the existence of a "switch" T cell derived from a patient with mycosis fungoides/Sezary's syndrome. The serum immunoglobulin profile in this patient revealed high IgG and IgA but no detectable IgM. Peripheral blood mononuclear cells from this patient secreted only IgG and IgA in the presence of pokeweed mitogen. T cells (Trac) co-cultured with normal allogeneic non-T cells and pokeweed mitogen resulted in only IgG and IgA PFC, with little or no IgM secretion. There was no evidence of active suppression of IgM. Rather, these T cells appeared to induce an Ig class switch from IgM to IgG and IgA, when co-cultured with mu+ tonsillar B cells. Further evidence was obtained using mononuclear cells derived from a patient with immunodeficiency and hyper-IgM, a syndrome characterized by a lack of IgG and IgA secretion. The addition of Trac cells to either peripheral blood mononuclear cells or non-T cells from a patient with hyper-IgM syndrome resulted in new secretion of IgG, with a concomitant decrease in IgM secretion, whereas control T cells were not effective in inducing secretion of any isotype other than IgM. Isolated Tac+ T cells from Trac appear to be responsible for this effect.

Antibody-Producing Cells↗
PubMed1985

T-cell subsets in multiple sclerosis: lack of correlation between helper and suppressor T cells and the clinical state.

Peripheral blood T-lymphocyte subsets were investigated in a group of 26 multiple sclerosis (MS) patients of different clinical categories and compared to those of 15 normal controls and 7 other patients with known immunoregulatory disorders. In addition 17 well-documented acute relapses in 11 MS patients were also studied, some of whom were tested serially prior to, during, and after the acute attack. Using three different commercial preparations of monoclonal antibodies directed against human T3, T4, and T8 lymphocyte markers, none of the MS patients irrespective of disease category exhibited any changes in the absolute numbers of T-cell subsets or ratios thereof; this was true during either quiescent or active stages of the disease. In contrast, several patients with known immunoregulatory disorders exhibited clear changes in T4/T8 ratios. Factors such as type of patient studied, sampling error, and methods of isolation of mononuclear cells, as well as source of monoclonal antibody, failed to explain the lack of change in T-cell subsets in these patients. Thus, our data fail to confirm the previous reports of a decrease in the absolute numbers of T8 cells or the increase in the T4/T8 ratios in active or quiescent MS patients. These negative findings underscore the need for further studies relating these markers to meaningful functional properties of these cells and their interaction with the relevant target organs.

Adult↗
PubMed1985

A membrane protein preferentially expressed by a subpopulation of immature lymphoid cells, epidermal basal keratinocytes, and other epithelial cells.

A murine monoclonal antibody, designated EL-1, was raised by immunization with a human malignant T cell line. It reacted specifically with a membrane antigen expressed on T and B lymphoblastoid cell lines, a subpopulation of normal thymocytes and bone marrow lymphocytes, lymphocytes from a subset of patients with non-B, non-T cell acute lymphoblastic leukemia or T cell acute lymphoblastic leukemia and epithelial stem cells. The latter reactivity was especially striking in the skin, where only basal epidermal keratinocytes and epidermal appendages, including eccrine sweat glands, sebaceous glands and hair follicles, stained positively. A human epidermoid carcinoma cell line was also stained by EL-1. Suprabasilar keratinocytes and acellular keratin did not stain. However, in vitro proliferating fetal lung fibroblasts stained positively. Membrane immunoprecipitation analysis demonstrated that the antigen recognized by antibody EL-1 is a single protein of molecular weight 105 kilodaltons which did not change with exhaustive chemical reduction. Metabolic radiolabeling studies demonstrated that this protein is synthesized by the cell and not merely taken up from the culture medium. This antibody can be useful in studying keratinocyte differentiation in epidermal malignancies and normal skin.

Animals↗
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

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↗