title: Lymphokine activation of T4+ T lymphocytes and monocytes.
abstract: The function of the T4 antigen, a marker for a differentiated T cell subset, is not well understood. Our previous observation that a chemoattractant human lymphokine, lymphocyte chemoattractant factor (LCF), which selectively induces motile responses in unactivated T4+ lymphocytes, led us to investigate whether LCF could also induce T4+ cell activation. Because LCF acts selectively on T4+ cells, we next determined whether the T4 antigen has a function in this LCF-induced cellular activation. A T4+ lymphocyte migratory response is induced by divalent anti-T4 antibody, but not by corresponding Fab fragments of the same antibody. Fab fragments of anti-T4 antibody, but not Fab fragments of anti-T3 antibody, block the migratory effect of both LCF and divalent anti-T4. Furthermore, LCF but not divalent anti-T4, evokes the expression of interleukin 2 (IL 2) receptors and HLA-DR antigen on T4+ lymphocytes in 24 hr. These effects are quantitatively similar to those observed by anti-T3 antibody activation. LCF-induced IL 2 receptor expression is blocked by co-incubation with anti-T4 antibody and anti-T4 Fab fragments, whereas anti-T3 activation is not inhibitable by anti-T4 Fab fragments. Because cultured monocytes express the T4 antigen, we investigated the action of LCF on cultured monocyte migration and HLA-DR expression. Induction of monocyte migration by LCF and anti-T4 antibody increases proportionally as T4 antigen expression increases in vitro. This enhanced migration is inhibitable by anti-T4 Fab fragments. Monocyte activation, as measured by augmented HLA-DR expression 24 hr after incubation with LCF, but not anti-T4 antibody, is quantitatively similar to the effects of interferon-gamma. Augmented HLA-DR expression is blocked by anti-T4 Fab fragments but not by antibody to interferon-gamma. These studies indicate that LCF interacts with T4+ lymphocytes and monocytes to induce migration and cellular activation.
mesh_terms: D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface / Q000032:analysis; D002478:Cells, Cultured; D002630:Chemotactic Factors / Q000494:pharmacology*; D002634:Chemotaxis, Leukocyte; D006684:HLA-DR Antigens / Q000276:immunology; D006801:Humans; D019410:Interleukin-16; D008213:Lymphocyte Activation; D008222:Lymphokines / Q000494:pharmacology*; D009000:Monocytes / Q000276:immunology*; D011971:Receptors, Immunologic / Q000378:metabolism; D015375:Receptors, Interleukin-2; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D002630:Chemotactic Factors; D006684:HLA-DR Antigens; D019410:Interleukin-16; D008222:Lymphokines; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2