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Biomedical subjects

M Feldmann

Publications and source records attributed to M Feldmann.

At least 379 records · Page 21Linked to original sources
PubMed1979

Induction of human antigen-specific and non-specific helper factors in vitro.

Human peripheral blood leucocytes, cultured for 4--6 days with the appropriate concentration of protein or synthetic polypeptide antigen, yield helper cells. These cells, after a further 24 hr incubation with the appropriate antigen release helper factors, which are of two types, antigen specific and non-specific; a similar situation to that described in the mouse. These factors are assayed by their effects on the plaque-forming cell response of mouse spleen cells cultures in vitro. The potential applications of this new assay for human T cell function are discussed.

Adult↗
PubMed1979

Selective production of human antigen specific helper factor from normal volunteers: implications for human Ir genes.

Based on previous systems for generating helper cells and factors from mouse spleen cell cultures, an in vitro system for the production and detection of human helper factors to the synthetic polypeptide antigens (T,G)-A--L and GAT10 was developed. The factors are made by human peripheral blood leucocytes and are antigen-specific, as judged both by functional criteria and specific binding and elution from antigen columns. Out of the first six volunteers studied two were high responders to (T,G)-A--L, but non-responders to GAT, two responders to GAT but not (T,G)-A--L. One subject made factors to both antigens and the sixth reacted to neither. The antigens chosen are known to be under MHC-linked immune response (Ir) gene control in all animal species tested, with some strains being responders while others are not. The selective responsiveness, different between individuals, thus suggests that the response to these antigens in man is under Ir gene control. Because of the small size of the sample initially studied and HLA typed, it was not surprising that there was no clear-cut association of response with any particular histocompatibility type at the HLA-A, B, C or D locus.

Adult↗
PubMed1979

Induction of antibody responses in vivo by antigen specific helper factor.

T helper cell factors (HF) have been preparated against protein and synthetic antigens by restimulating in vitro induced helper cells with small amounts of antigen. HF when tested in vitro are antigen specific and capable of replacing T cells, initiating a thymus dependent IgM response. In the in vivo adoptive transfer assay HF is capable of replacing T helper cells and is active at very high dilution, inducing both IgM and IgG responses. When tested on unirradiated DNP primed animals the HF was able to initiate a thymus dependent anti-hapten response, comparable to that seen with helper T cells, of both IgM and IgG class. It was also shown that HF acts on anti-Thy 1 treated spleen cells. The results indicate that antigen specific helper factors may be one of the physiologic mediators of T-B interactions in intact animals.

Animals↗
PubMed1979

Structural characteristics of antigen-specific suppressor factors: definition of 'constant' region and 'variable' region determinants.

Anti-suppressor factor antisera, prepared either in rabbits (R alpha SF) or in syngeneic (CBA) mice (M alpha SF) by repeated immunisation with antigen purified CBA antigen specific suppressor factor reactive to KLH was shown to abolish the suppression caused by suppressor factors (SF) in vitro. R alpha SF inhibited the function of all SF regardless of their strain of origin or their antigen specificity suggesting that it recognized 'constant region'-like determinants in SF molecules. It did not have any effect on antigen-specific helper factors. Syngeneic M alpha SF only abolished the function of suppressor (or helper) factors which were KLH-specific, and only provided they were derived from the appropriate strains of mice; thus resembling the effects of anti-idiotype antibody. No linkage to MHC could be demonstrated but there was some evidence of possible association with allotype. A schematic structure of the SF molecule is suggessted on the basis of these findings with antisera to SF.

Absorption↗
PubMed1978

Suppressor-cell induction in vitro. IV. Target of antigen-specific suppressor factor and its genetic relationships.

Antigen-specific suppressor factor produced by metabolically active in vitro-induced suppressor cells, upon further antigenic stimulation, act on nylon wool nonadherent, Ly-2-negative target cells within helper cell population, resulting in suppression of both the IgM and IgG antibody responses. Thus the target is an Ly-1+ T cell, possibly the helper cell. All the mouse strains tested so far have been able to produce the factor, and when tested in CBA or B10 mice, there seems to be no genetic restriction involved e.g., nonsyngeneic suppressor factors suppress as well as do the syngeneic factors. Comparison of the properties of suppressor factor with those of extracts of suppressor cells yield differences in origin, target of action and effect, indicating that these are different molecules. The heterogeneity of suppressor pathways is discussed.

Animals↗
PubMed1978

Complexity of cell interactions: analysis using antigens under Ir gene control.

The properties of three I region associated immunoregulatory factors involved in cell interactions are described. These are antigen specific T helper factor, suppressor factor produced by metabolically active T cells and genetically restricted factor, which is produced by macrophages and is involved in T helper cell induction. The use of these factors to analyse cell interactions is discussed.

Animals↗
PubMed1977

T-T interactions in the induction of suppressor and helper T cells: analysis of membrane phenotype of precursor and amplifier cells.

The Ly and Ia phenotypes of T lymphocytes involved in the in vitro generation of helper and suppressor cells were identified. The precursors of both cells are found in adult thymectomized spleen. Helper precursors are Ly-1+2-3-Ia-, while suppressor precursors are Ly-1-2+3+Ia-, although the suppressor effector is Ia+. In both cases a second 'amplifier' cell is required for differentiation of precursors to occur. This cell is found in anti-lymphocyte serum-treated spleen and has the phenotype Ly-1+2+3+Ia-.

Animals↗
PubMed1977

Suppressor cell induction in vitro. III. Antigen-specific suppression by supernatants of suppressor cells.

Antigen-specific suppressor T cells induced in vitro release, after a further period of culture in vitro with antigen factors into the supernatant which have suppressor activity. These suppressor factors (SF) have the same antigen specificity as the suppressor cells (SC). SF only works on the early phase of thymus-dependent responses in cultures. SF inhibits thymusdependent IgM, but not thymus-independent IgM responses in vitro. SF is is destroyed by proteolytic enzymes, and inactivated at 80 degrees C for 30 min. The release of SF from SC is dependent on the presence of antigen and metabolically active cells.

Animals↗