SPECIFIC T-CELL FACTORS THAT INITIATE CELLULAR IMMUNE-RESPONSES ARE PRODUCED BY CD4(-), CD8(-), V(BETA)8(-) LYMPHOCYTES AND ARE PRESENT IN NUDE-MICE

The antigen-specific suppressor inducer T-cell factors (TsiF) specific macrophage-arming factor (SMAF) and mast cell-arming T-cell factor (M TCF) are produced by lymphocytes that have a Thy 1(+), Lyt-1(+), CD4(- ), CD8(-), and V(beta)8(-) phenotype. The SMAF- and MTCF-producing lym phocytes are positive for the monoclonal antibody (mAb) 14-30, which i s directed against TsiF and also binds SMAF and MTCF. The SMAF-produci ng lymphocytes are negative for mAb 14-12, which is directed against s uppressor effector T-cell factors. The MTCF-producing lymphocytes are probably CD3(+). The CD3 phenotype of SMAF-producing lymphocytes could not be established in the biological assays. Lymphocytes mediating th e classical (24 hr) delayed-type hypersensitivity (DTH) response are T hy 1(+), CD3(+), CD4(+), CD8(-), V(beta)8(+). SMAF- and MTCF-producing lymphocytes were also detected in congenitally athymic (nude) mice. W e conclude from these results that (i) the subset of lymphocytes (CD4( -), CD8(-), V(beta)8(-)) that produces SMAF and MTCF (and is involved in the initiation of the cellular immune response) is different from t he subset (CD4(+), V(beta)8(+)) that exerts effector functions, like D TH or cell-mediated immunity. (ii) In case of a CD3(+) phenotype of SM AF- and MTCF-producing lymphocytes, this CD3(+), CD4(-), CD8(-) phenot ype together with their presence in nude mice suggests that these lymp hocytes may bear a gamma delta T-cell receptor (TCR), although an ap T CR positive phenotype cannot be excluded. (iii) Since SMAF- and MTCF-p roducing lymphocytes bind mAb 14-30, these TsiF can be associated with the plasma membrane of the lymphocytes by which they are produced. (C ) 1994 Academic Press, Inc.