In vitro Induction of Cytotoxic T Lymphocytes against HTLV‐I‐infected T‐Cells from Adult T‐Cell Leukemia Patients, Asymptomatic HTLV‐I Carriers and Seronegative Healthy Donors

We investigated an in vitro method to produce cytotoxic T lymphocytes (CTLs) against HTLV‐I‐infected T‐cells using peripheral blood mononuclear cells (PBMC) of adult T‐cell leukemia (ATL) patients, asymptomatic HTLV‐I carriers (AC) and seronegative healthy donors. The PBMC were restimulated repeatedly for 4 weeks with HLA‐matched HTLV‐I‐infected T‐cells which had been pretreated at 56deg;C for 30 min to inactivate infectious HTLV‐I. The culture medium included 10–100 units/ml of recombinant lymphokines (rIL‐1, rIL‐2, rIL‐4, rIL‐6 and rIL‐7) and 10% fetal calf serum in RPMI‐1640 medium. The cytotoxic activity was measured against HLA‐matched HTLV‐I‐infected T‐cell lines after CD4(+) or CD8(+) cells were positively panned from the cultured PBMC. The PBMC of ATL, AC and healthy donors were able to produce either CD4(+) or CD8(+) CTLs against HTLV‐I‐related antigens (env, gag, p21(x), p27(rex) and p40(tax)) as well as the antigen(s) of as‐yet unknown specificity expressed on HTLV‐I‐infected T‐cells. All the CTLs recognized the specific antigens in the context of either class I or class II HLA types. These results indicated that ATL patients, AC and healthy donors were immunocompetent to generate CTLs against HTLV‐I‐infected T‐cells and probably against HTLV‐I‐transformed T‐cells.