HLA class-II-specific T-lymphocyte clones with dual alloreactive functions.

The relationship between T lymphocytes that proliferate in response to HLA class II antigens and those that mediate the cytotoxic response toward HLA class II target antigens was investigated. Alloreactive T-cell clones were derived under conditions in which the likelihood of clonality was high. Three populations of HLA class-II-specific T cells were identified. Two of these populations exhibited only HLA class-II-directed cytotoxicity or HLA class-II-induced proliferation. The third population of T cells exhibited both of these responses.