Measles virus-specific T4⁺ human cytotoxic T cell clones are restricted by class II HLA antigens

We have generated measles virus-specific T cell clones from a patient with multiple sclerosis who has been described previously as a strong responder to measles virus. T cell clones were screened on the basis of their capacity to proliferate to measles virus. The cell surface phenotype of each clone was OKT3⁺, OKT4⁺, OKT8^-. The majority of these clones (11 of 14) were cytotoxic for their autologous measles virus-infected lymphoblastoid B cell target. This cytotoxicity was specific for measles virus inasmuch as these T cell clones could not lyse influenza or mumps virus-infected B cell targets. By using a panel of HLA-defined measles virus-infected B cell lines, these clones were shown to recognize measles virus in the context of HLA class II determinants. A monoclonal antibody that recognizes HLA class II monomorphic determinants (L243), but not a monoclonal antibody that recognizes HLA class I antigens (W6/32), inhibited the lysis of the autologous measles virus-infected B cell target by these T cell clones. These results demonstrate that these cytotoxic T cell clones specific for measles virus are HLA class II restricted.