Differential sensitivity of IgG memory subpopulations to allogeneic thymocytes: Positive and negative signals

H. Golding, M. B. Rittenberg

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Abstract

Spleen cells from mice primed to trinitrophenyl keyhole limpet hemocyanin (TNP-KLH) can generate anti-TNP IgG plaque-forming cells when stimulated in vitro with either T-dependent (TD) or T-independent (TI) conjugates of the TNP epitope. The cells responding to TD or T1 antigens can be eliminated selectively by exposure to antigen, bromodeoxyuridine, and light. These functionally distinct subpopulations of memory B cells have been tentatively designated B2γ (TD responders) and B1γ (TI responders). We have found using an in vitro 'allogeneic effect' model that secondary responses to TD and TI antigens were modified differently by alloreactive thymus cells. The TD response was highly sensitive to 'negative signals' (50 to 90% suppression), whereas TI IgG responses were resistant to suppression and were frequently enhanced by the presence of allogeneic T cells. Limiting dilution analysis in the presence of allogeneic thymocytes showed a reduction in the frequency of B2γ precursors and an increase in the frequency of B1γ precursors under the same experimental conditions. Pretreatment of the added allogeneic thymocytes with mitomycin C eliminated the suppression of the TD response but did not alter the response to the TI complexes. To define the immediate target of the alloreactive thymocytes, successful cooperation was established between mitomycin C treated KLH-primed T cells and TNP-primed B cells from partially histoincompatible congenic strains. Unprimed thymocytes were then added, which could only recognize as foreign either the B cell or the T-helper cell. Only thymocytes allogeneic to the primed B cells produced the differential effects described above. No effect was observed when the T helper cells were the allogeneic target.

Original languageEnglish (US)
Pages (from-to)1284-1290
Number of pages7
JournalJournal of Immunology
Volume124
Issue number3
StatePublished - Jan 1 1980

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ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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