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Biomedical subjects

K Eichmann

Publications and source records attributed to K Eichmann.

At least 127 records · Page 7Linked to original sources
PubMed1983

Limiting dilution analysis of alloreactive T helper cells: precursor frequencies similar to that of alloreactive cytotoxic T cells.

Precursor frequencies for alloreactive T helper cells involved in the generation of primary cytotoxic responses from thymocytes were determined in splenic T cells and selected Lyt-1 lymphocytes by limiting dilution analysis. T helper precursors at frequencies ranging from 1/5000 to 1/13,500 were found in individual experiments in unsensitized selected Lyt-1 populations reacting to H-2 alloantigens. After preactivation of Lyt-1 lymphocytes with antigen in limiting dilution, the frequencies of T helper cells were increased 2-3 fold when cultured in the absence and 10-50-fold when cultured in the presence of T cell growth factor. The frequencies for T helper precursors found in Lyt-1 cells were comparable to those of unselected T cells, indicating that a significant portion of T helper cells resides in the Lyt-123 population. Activation of T helper precursors with H-2 antigens or with H-2 and non-MHC (plus MLs) antigens resulted in similar frequencies, suggesting that the same T cell can respond to H-2 and non-MHC determinants. The data suggest that alloreactive T helper precursors exist at frequencies similar to that of CTL precursors. In addition, the results indicate that the induction of CTL by T helper cells is subject to regulation presumably by suppressive cells and that Lyt-1 inducer cells may be involved in the development of suppression for CTL responses.

Animals↗
PubMed1982

Quantitative studies on T cell diversity. III. Limiting dilution analysis of precursor cells for T helper cells reactive to xenogeneic erythrocytes.

Splenic T cells exposed to concanavalin A (Con A), and subsequently to factors produced by rat spleen cells in response to Con A (Con A sup), acquire the ability to function as helper T (TH) cells in response to xenogeneic erythrocytes (RBC). Help is measured as the reconstitution of the plaque-forming cell response of a spleen cell population depleted of T cells by treatment with anti-Thy-1 serum and complement. We propose that precursor TH cells differentiate during the in vitro treatment into mature TH cells. As differentiation occurs under limiting dilution conditions, an estimation of the precursor frequency should in principle be possible. However, a single-hit Poisson distribution does not fit our data. Instead, we observe, dependent on the T cell concentration, three separate "peaks" of response. In many experiments, using sheep, horse, and chicken RBC as antigens, we reproducibly find these "peaks" at 40-190, 600-3,000, and 20,000-100,000 T cells, placed into limiting dilution cultures, respectively. By various experiments we can show that the helper activity is not due to passively transferred rat factors, but to the titrated cells themselves. The active cell is a T cell that appears to function in an antigen-specific way and to require direct cell contact to do so. It thus resembles the classical helper T cell. As we find precursor TH cells already at very low concentrations of T cells, we titrated the range between 0 and 100 T cells/well carefully. The bent shape of the titration curves does not always allow a statistically satisfying regression analysis, and we therefore cannot estimate precise precursor frequencies from every experiment. However, a common sense argument can be made that these frequencies must be on the order of 1/10-1/100 T cells. We propose that the limiting dilution curves obtained in this system most likely reflect fundamentally important cellular interactions that regulate immunological effector functions. We favor a concept of independently interacting sets of helper and suppressor T cells of various frequencies, but other models are possible.

Animals↗
PubMed1982

Expression of Qat-4 and Qat-5 alloantigens on cytotoxic precursor and effector cells: different surface phenotypes of alloreactive and H-2 restricted cytotoxic T cells.

Monoclonal anti-Qat-4 and anti-Qat-5 antibodies, which define antigens expressed on peripheral T cell subsets, have been used to study the phenotypes of alloreactive and H-2-restricted cytotoxic effector cells and their precursors. Depletion of Qat-4+ or Qat-5% cells from the T cell pool prior to their sensitization in bulk cultures prevented the development of alloreactive and H-2-restricted cytotoxic activities in the selected populations. No reconstitution of cytolytic activities to normal levels was obtained when mixtures of Qat-4- and Qat-5- cells were sensitized in bulk cultures to H-2 or non-H-2 antigens. Sensitization of limiting numbers of Qat-4- or Qat-5- lymphocytes under optimal conditions for help (interleukin 2), with the appropriated antigens (H-2 or H-Y) did not result in the generation of cytotoxic T cells, indicating that the majority of all cytotoxic T lymphocyte (CTL) precursors are Qat-4+, Qat-5+. When CTL effector populations were treated with the antisera and complement (C) at their maximum CTL activity, it was found that H-2-restricted CTL were totally eliminated by anti-Qat-4 and considerably reduced by anti-Qat-5 antisera and C. In contrast, alloreactive CTL effector cells were insensitive to anti-Qat-4 and to anti-Qat-5 plus C. Although alloreactive CTL effector populations regained some Qat-4 antigens during further in vitro culture, it was shown that H-2-restricted CTL were at all times more sensitive to anti-Qat-4 than were alloreactive CTL. The findings suggest that during maturation of alloreactive and H-2-restricted CTL from their precursors, both alloantigens undergo differential quantitative variations in their expression that lead to different Qat-4,5 phenotypes of alloreactive and H-2-restricted CTL.

Animals↗
PubMed1982

Clonal analysis of a human lymphoblastoid cell line (B17) secreting antibody to N-acetyl-D-glucosamine.

In this paper we analyse the clonal composition of a human lymphoblastoid B-cell line secreting IgM/k antibody to N-acetyl-D-glucosamine, the immunodominant sugar of Group-A-streptococcal carbohydrate. Besides non-antibody secreting cells, the line consists of two clonotypes of antibody-secreting cells: B17 cells producing over 90% and F6 cells producing less than 10% of the antibody in the supernatant. The proportions of B17 and F6 cells in the cell line seem to be similar to the proportion of antibodies in the supernatant. F6 cells can be isolated by cloning and maintained as stable lines, whereas this is more difficult with B17 cells. The results suggest that upon establishment of the line, at least two N-acetyl-D-glucosamine-specific B cells were immortalized and coexist together as independent clonotypes. Although F6 cells seem to have a slight tissue culture advantage, they represent the minor clonotype in the B17 cell line.

Acetylglucosamine↗
PubMed1981

Quantitative studies on T cell diversity. II. Determination of the frequencies and Lyt phenotypes of two types of precursor cells for alloreactive cytotoxic T cells in polyclonally and specifically activated splenic T cells.

Two different limiting dilution systems have been applied to compare precursor frequencies of alloreactive cytotoxic T cells (CTL-P) in the polyclonally and specifically activated lymphocyte populations and in selected Lyt T cell subsets. Both systems make use of T cell growth factor for T cell expansion but differ with respect to the activation step in that lymphocytes are either activated directly with allogenetic stimulator cells or are sensitized polyclonally with concanavalin A (Con A) in bulk culture before their expansion under limiting dilution conditions. In polyclonally activated C57BL/6 lymphocyte populations, two types of CTL-P specific for H-2d alloantigens could be identified: a frequent set with a frequency of 1/100-1/300, and a rare set with a frequency of 1/2,000-1/8,000. In contrast, only a single CTL-P set was found in specifically activated populations with a frequency similar to that of the frequent CTL-P found on Con A blasts. In Con A blasts, the frequent at higher cell concentrations by suppressor T cells, whereas rare CTL-P were insensitive to this suppressive mechanism. Whereas in specifically activated T cells, the predominant CTL-P phenotype was Lyt-123, the predominant Lyt phenotypes for the frequent and the rare CTL-P found in Con A blasts were Lyt-123 and Lyt-123, respectively, which suggests that they represent primary and secondary CTL-P, respectively. The results are discussed with respect to previous reports on the involvement of Lyt T cell subsets in the generation of cytotoxic responses and their regulation by T suppressor cells.

Animals↗
PubMed1981

Generation of effector cells from T cell subsets. III. Synergy between Lyt-1 and Lyt-123/23 lymphocytes in the generation of H-2-restricted and alloreactive cytotoxic T cell.

Lyt-123/23 and Lyt-1 T cell subsets, positively selected by separation on the fluorescence-activated cell sorter, were tested in vitro for their role in the generation of H-2-restricted and alloreactive cytotoxic T cells. It is shown that in the proliferation assay, both T cell subsets responded equally well to H-2 and non-H-2 antigens (H-Y), respectively. In contrast, none of the selected Lyt subsets, but only the mixed population containing Lyt-1 and Lyt-123/23 lymphocytes gave rise to both H-2-restricted (anti H-Y, anti-trinitrophenyl) and alloreactive (anti-H-2) cytotoxic lymphocytes. The data imply an essential role of Lyt-1 cells as inducers or helpers in the generation of all cytotoxic lymphocytes from their precursors in the Lyt-123/23 pool.

Animals↗
PubMed1981

Genetic control of B cell function. II. Antibody responses of inbred mice to red blood cells are controlled at the B cell level.

Inbred strains of mice can be classified into high and low responders with respect to their antibody responses to RBC. In this paper, we investigate the cellular basis of the difference in responsiveness between high- and low-responder strains. In cell-mixing experiments with purified B cells, T cells, and macrophages from 2 different combinations of H-2-identical high- and low-responder strains, we find that the B cells determine high and low responsiveness, whereas T cells and macrophages from low responders function equally as well as those of high responders. We could also exclude that suppressor T cells play an important role in determining high and low responsiveness. It is therefore suggested that low responsiveness is a defect of B cells to become activated in a T helper cell-dependent antibody response. In the previous paper of this series we showed that a limited number of genes (possibly 2), 1 linked to the Igh gene complex and the other(s) of unknown linkage, control the level of responsiveness. Taken together, we think that this represents a novel example of a genetic polymorphism in B cell function that is sufficiently simple, genetically and functionally, to provide a genetic approach to the study of B cell activation.

Animals↗
PubMed1980

Quantitative studies on T cell diversity. I. Determination of the precursor frequencies for two types of streptococcus A-specific helper cells in nonimmune, polyclonally activated splenic T cells.

A limiting-dilution system is described that makes use of T cell growth factor T cell expansion and allows the determination of precursor frequencies for various regulatory and effector T cells in nonimmune, polyclonally, or specifically activated T cell populations. Two different sets, a frequent and a rare set, of T helper cell precursors with specificity for trinitrophenyl-group A streptococcal vaccine, could be identified: the frequent set is of the Lyt-123 phenotype, and is present at frequencies of from 1/1,000 to 1/6,000 splenic T cells. It is only active at low cell numbers, whereas it is completely inactivated at greater cell numbers, presumably by suppressor T cells of lower frequency but greater potency. The rare set is of the Lyt-1 phenotype, is present at frequencies of from 1/10,000 to 1/70,000, and is not sensitive to suppressor cells present within the tested cell numbers. We suggest that the frequent set contains primiary helper cell precursors, whereas the rare set contains helper T memory cells preselected by previous exposure to other antigens. The results are discussed with respect to other reports on the involvement of more than one set of helper cells in antibody production.

Animals↗
PubMed1980

Antigen receptors on major histocompatibility complex-restricted T lymphocytes. I. Preparation and characterization of syngeneic antisera against trinitrophenyl-activated T cell blasts and demonstration of their specificity for idiotypes on cytotoxic T lymphocytes.

This paper describes the specificity of AKR anti-(a) [AKR anti-trinitrophenylated AKR (AKR-TNP)] [AKRa (AKRaAKR TNP)] antisera raised in syngeneic AKR mice against AKRaAKR-TNP cell populations enriched for H-2-restricted aTNP cytotoxic lymphocytes (CTL) by blast-cell isolation. The activity of the antisera resided in the Ig fraction. All antisera were shown to reproducibly react with AKRaAKR-TNP-CTL-containing cell populations in indirect immunofluorescence and all removed the major fraction of CTL in complement-dependent lysis causing a considerable depression of cell-mediated lympholysis. The antisera were nonreactive with alloreactive AKRaC57BL/6 CTL and other H-2-restricted AKR CTL against fluorescein-isothiocyanate-conjugated AKR-target cells. It could be excluded that the antisera contained contaminating antibodies against TNP, TNP-neoantigenic determinants (NAD), or processed CTL-receptor-bound TNP-NAD, thus demonstrating specificity for determinants on T cell receptors of AKRaAKR-TNP CTL. These receptors were produced by the CTL themselves. These observations are interpreted to suggest that AKRa (AKRaAKR-TNP) antisera contain anti-idiotypic antibodies directed against specificity-associated determinants (idiotypes) on T cell receptors of H-2-restricted AKRaAKR-TNP CTL. The antisera provide a new tool to study the genetic control of idiotype expression on H-2-restricted CTL, the biochemistry of T cell receptors, and the regulation of the generation of H-2 restricted CTL on the idiotype level.

Animals↗
PubMed1980

Correlated expression of VH framework and VH idiotypic determinants on T helper cells and on functionally undefined T cells binding group A streptococcal carbohydrate.

Antibodies to framework determinants of the VH and V lambda fragments of MOPC 315 and antisera to the VH idiotype determinants of the A 5 A antibody were used to analyze the antigen receptors of mouse T (and B) cells. This was done by using the antibodies as inhibitors in (a) an assay in which the binding of radiolabeled streptococcal carbohydrate (A-CHO) antigen by primed and unprimed T and B cells is determined and (b) an assay in which the helper activity of group A streptococcal vaccine-primed T cells is determined. The results suggest that the major proportion of primed and unprimed T cells binding A-CHO (70-90%) exhibit VH framework and VH idiotypic determinants. This population appears to include the helper T cells. A minor proportion of T cells (10-30%) express V lambda-related framework determinants and lack VH framework and VH idiotypic determinants. This population does not include T helper cells. Taken together, the data suggest that a subpopulation of T cells, including the helper cells, uses entire Ig VH regions as part of their antigen receptor system.

Animals↗
PubMed1979

Induction and characterization of isogeneic anti-idiotypic antibodies to BALB/c myeloma S117: lack of reactivity with major idiotypic determinants.

Isogeneic anti-idiotypic antibodies were induced by immunization of BALB/c mice with the BALB/c-derived myeloma protein S117 which binds N-acetylglucosamine-containing antigens including Group A streptococcal carbohydrate (A-CHO). Most BALB/c mice produced anti-S 117 idiotypic antibodies, as shown by various different immunization protocols. The antibodies of individual mice were of intermediate to high affinity (2.8 x 10(6) M-1 to 1.4 x 10(8) M-1). In isoelectric focusing, most individual antibodies were shown to consist of a small number of clonotypes, but each mouse produced its own unique set of clones so that the potential clonal repertoire of strain BALB/c is rather large. Most importantly, all isogeneic anti-idiotypic antibodies were directed against idiotypic determinants of S117 that are not shared with induced anti-A-CHO antibodies, whereas it has been shown previously that allogeneic and xenogeneic anti-S 117 idiotypic antibodies react with idiotypic determinants unique to S 117 as well as with those that are shared with anti-A-CHO antibodies. The data suggest that the expression of S 117 idiotypic determinants in strain BALB/c is not under antibody-mediated, anti-idiotypic feedback control.

Acetylglucosamine↗