Effect of tumor promoter 12-O-tetradecanoyl-phorbol 13-acetate on CD 7 expression by T lineage cells.
Phorbol esters exert diverse effects on cellular activation and differentiation. CD 7, a differentiation antigen appearing early in T cell ontogeny, may be involved in the activation and differentiation processes. CD 7 was found to be rapidly down-regulated by 12-O-tetradecanoylphorbol 13-acetate (TPA) from mature T cell surface. The time course of CD 7 down-regulation was similar to that of other functionally important T cell antigens, CD 3 and CD 4. Within 2 h, TPA at 10 to 30 ng/ml induced a complete down-regulation of CD 7. Twenty-four hours later, the reappearance of CD 7 on TPA-treated cells was observed. This phenomenon was monocyte independent. In contrast, CD 7 expression on thymocytes was resistant to the effect of TPA. In addition, certain leukemic T cells were also resistant to TPA-induced CD 7 down-regulation. The mechanism underlying TPA-induced CD 7 down-regulation was investigated further. Synthetic diacylglycerol, sn-1,2-dioctanoylglycerol, which activates protein kinase C, did not induce down-regulation of CD 7 on mature T cells. Ionomycin, a calcium ionophore, did not down-regulate this antigen either. Thus, it is concluded that the processes of protein kinase C activation and/or cytosolic calcium influx are not sufficient for TPA-induced CD 7 down-regulation; other pathways induced by TPA may be responsible.
Jung
L K
LK
Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City 73104.
Fu
S M
SM
D000911:Antibodies, Monoclonal / Q000276:immunology; D000945:Antigens, Differentiation, T-Lymphocyte / Q000096:biosynthesis* / Q000276:immunology; D003864:Depression, Chemical; D004075:Diglycerides / Q000494:pharmacology; D004987:Ethers / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D015759:Ionomycin; D007938:Leukemia / Q000473:pathology; D010716:Phosphatidylinositols / Q000378:metabolism; D013601:T-Lymphocytes / Q000187:drug effects* / Q000276:immunology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000276:immunology
D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D004075:Diglycerides; D004987:Ethers; D010716:Phosphatidylinositols; C044295:1,2-dioctanoylglycerol; D015759:Ionomycin; D013755:Tetradecanoylphorbol Acetate