A glycoprotein antigen detected with new monoclonal antibodies on the surface of human lymphocytes infected with human T-cell leukemia virus type-I (HTLV-I).

We have prepared two new mouse monoclonal antibodies (MAbs) named TARM-34 (IgM) and TAG-34 (IgG1), that react with surface antigens of lines of human lymphocytes bearing a human T-cell leukemia virus type-I (HTLV-I). The characters of these antibodies are compared with those of anti-HTLV-1 gp21 MAb (TA-21, IgG1), anti-HTLV-I p19 MAb (GIN-14, IgG1) and human antibodies from patients with adult T-cell leukemia (ATL). An indirect membrane immunofluorescence assay showed that TARM-34, TAG-34 and TA-21 all reacted specifically with cell-surface antigens of HTLV-I-positive T- and B-cell lines and cultured peripheral blood lymphocytes from HTLV-I-infected adults. Radioimmunoassay showed that serum antibodies from the ATL patients interfered with the binding of TA-21 antibody to cells of the HTLV-I-positive T-cell line MT-2, but not with the bindings of TARM-34 and TAG-34 antibodies. TARM-34 and TAG-34 both precipitated a 34-kd glycoprotein (gP34), while TA-21 precipitated gp21 from a lysate of 3H-glucosamine-labelled MT-2 cells. TARM-34 and TAG-34 also precipitated the 34-kd protein from lysates of MT-2 and HUT 102 cells labelled with 125I- or 35S-cysteine. Interestingly, TARM-34 and TAG-34 also precipitated 35-kd protein from a lysate of other HTLV-I-positive cells (F-Taj cell line) derived from an ATL patient. TA-21 precipitated the 21-kd protein from the lysates of 35S-cysteine-labelled HTLV-IMT-2 virions, but TARM-34 and TAG-34 did not precipitate any protein from this lysate. TARM-34 lysed HTLV-I-bearing cells in the presence of rabbit complement. These results indicate that TARM-34 and TAG-34 both recognize a glycoprotein antigen that is expressed on the surface of HTLV-I-infected cells.