Diversity of immunobiological functions of T-cell lines established from patients with adult T-cell leukaemia

In order to understand the variety of HTLV-1-associated cutaneous diseases, we studied the cytological profile of HTLV-1-infected T-cell lines established from patients with adult T-cell leukaemia (ATL). Among four CD4⁺ cell lines, termed 16T(-), 35T(-), MH-1, and KS-2, the 16T(-) cells secreted elevated quantities of IL-4, IL-6 and IFN-γ, and expressed mRNA for each cytokine in the absence of exogenous stimulation. The 35T(-) cells secreted IL-6 and a small amount of IFN-γ, but not IL-4. The MH-1 and KS-2 cells secreted only IL-6 in the absence of stimulation. In response to stimulation with phorbol-12-myristate-13 acetate (PMA), the 16T(-) cells produced more IL-4 and IFN-γ, whereas the 35T(-) and MH-1 cells exhibited increased secretion of IFN-γ, but still no IL-4 or IL-4 mRNA production. Although neither IL-4 nor IFN-γ were found in the culture supernatant of KS-2 cells, the production of IL-4 mRNA was detected by RT-PCR. Culture supernatants from the 16T(-) and 35T(-) cells induced the expression of intercellular adhesion molecule-1 (ICAM-1) and HLA-DR by cultured keratinocytes. This response was inhibited by pretreatment of the supernatant with anti-IFN-γ antibodies. These results indicate that some HTLV-1-infected T-cell lines constitutively secrete various cytokines, including biologically active IFN-γ. The diversity of immunobiological functions of the T-cell lines may be related to the variety of clinical features present in ATL patients.