title: Activation of human alloreactive cytotoxic precursor T lymphocytes.
abstract: The requirements for allogeneic T-cell activation have been studied in experiments with T and/or B cells as stimulator. Although target determinants (TDs, defined by CTL effectors in CML) are present on B and T cells used as target cells, this study indicates that TDs are functionally different when expressed on B and T cells used as stimulator cells, as only B cells can activate CTL precursors. Further, the study confirms that inducing TDs and strong lymphocyte-activating determinants (LADs, defined by proliferation in MLC) can be distinct structures found on two different stimulator B cells. The study suggests that binding of cytotoxic precursor T cells to TDs per se does not allow any detectable activation or start of proliferation and differentiation but requires another function of the stimulator cells in the non-T-cell compartment. The nature of this function is unknown, but it is the background for the first signal received by the TD-specific clones of CTL precursors, resulting in the expression of growth receptors for T-cell growth factor or interleukin 2 which is the second signal necessary for clonal expansion and differentiation.
mesh_terms: D001402:B-Lymphocytes / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D000939:Epitopes / Q000276:immunology; D006801:Humans; D008213:Lymphocyte Activation; D013601:T-Lymphocytes / Q000145:classification / Q000276:immunology*
chemical_list: D000939:Epitopes