REGULATION MECHANISMS OF ACTIVITY OF T LYMPHOCYTES - APPLICATIONS TO INFECTIVE AND TUMORAL PATHOLOGY .1. DELAYED-HYPERSENSITIVITY AND HUMORAL RESPONSE

  • 1 January 1976
    • journal article
    • research article
    • Vol. 24  (1) , 67-74
Abstract
Delayed-type hypersensitivity (DTH) develops in the absence of an adjuvant when mice are injected with an appropriate dose of sheep red blood cells (SRBC). Increasing the dose of SRBC reduces and eventually abolishes all evidence of DTH, and no further sensitization can be achieved even with the optimal s.c. injected dose; an exception is splenectomized mice in whom the development of DTH is not suppressed, even by massive doses of SRBC. This is also true in mice treated with cyclophosphamide (CY) which selectively suppresses the antibody response. The suppression of T [thymus-derived] cell activity measured as DTH cannot be due to antigen as such. The serum of blocked animals partially inhibits the induction and expression of DTH, and its blocking activity increases substantially after partial absorption. Absorbed serum did not inhibit (in vivo) the proliferative response nor the number of plaque forming cells to SRBC in peripheral lymph nodes; it increases the hemagglutinating titer of circulating specific antibody even though DTH is totally suppressed. The products of the interaction between antigens and antibodies probably block the activated T cells, which mediate DTH, without interfering with helper cells.

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