title: Alternative pathways of T lymphocyte activation.
abstract: Data presented in this paper suggest that there may be two alternative pathways which T lymphocytes can use in generating a cytotoxic response to alloantigens in vitro. First, there is the pathway taken when stimulator and responder cells differ by an entire H-2 complex where Ly1+2- helper T lymphocytes respond to I region encoded lymphocyte defined differences and provide help to the Ly1-2+ cytotoxic T lymphocytes responsive primarily to K/D region encoded cytotoxicity defined determinants. Second, there is the pathway taken when stimulator and responder cells differ by only K or D region differences without an I region encoded difference; under these conditions, an Ly1+2+ cell, which does not appear to play a significant role in the development of a cytotoxic response to an entire H-2 difference, appears to play a pivotal role.
mesh_terms: D003602:Cytotoxicity, Immunologic; D005802:Genes, MHC Class II; D006183:H-2 Antigens / Q000235:genetics; D007519:Isoantigens; D008213:Lymphocyte Activation; D008285:Major Histocompatibility Complex; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D006183:H-2 Antigens; D007519:Isoantigens