Human T lymphocytes and monocytes bear the same Leu-3(T4) antigen.
An analysis of the cellular distribution, biosynthesis, and structure of the human T lymphocyte antigen Leu-3(T4) was performed. By using a sensitive ELISA as well as FACS analysis, relative quantities of the Leu-3(T4) antigen from whole cell lysates and from cell surfaces of six cell lines were determined. The T-T hybrid cell line 255.88, and the monocyte/macrophage cell line U937, proved to be high producers of the antigen and were chosen for additional investigation. The Leu-3(T4) antigens from the T lymphocyte cell line and the monocyte/macrophage cell were shown to be identical by SDS-PAGE. Leu-3(T4) was a polypeptide of 55,000 AMW under reducing conditions, and 63,000 AMW under nonreducing conditions. In the 255.88 cell line, a second band of 41,000 AMW was associated with the true Leu-3(T4) molecule. The 55,000 AMW Leu-3(T4) molecule was shown to possess a high mannose sugar side chain, and to contain few accessible tyrosine residues. These studies demonstrate that human T lymphocytes and monocytes produce and process similar molecules that react with the anti-Leu-3(T4) monoclonal antibody. They also characterize this important associative antigen recognition structure and suggest that cells other than the T lymphocyte may be targets for the retrovirus HTLV-III.
D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface / Q000032:analysis*; D002460:Cell Line; D005434:Flow Cytometry; D006023:Glycoproteins / Q000032:analysis / Q000276:immunology; D006801:Humans; D008970:Molecular Weight; D009000:Monocytes / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*
D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D006023:Glycoproteins