Demonstration of HLA restricted killer cells in patients with acute measles.

The relationship between HLA determinants on effector and target cells and cell-mediated cytotoxicity was studied using the release of 51Cr from measles virus-infected PHA-blasts. HLA compatibility between effector and target cells was not required if effector lymphocytes were derived from measles seropositive adults, from a patient with SSPE, and from children after live measles vaccination. Cytotoxicity was always abolished after removal of Fc receptor-bearing lymphoid cells. In these donors, the effect is, therefore, probably due to K cells. In contrast, lymphocytes from children with acute measles preferentially killed those virus-infected target cells with which they shared HLA antigens. Selective lytic activity was still observed after elimination of Fc receptor-bearing lymphoid cells. It is suggested that HLA-dependent killer cells represent specific cytotoxic T lymphocytes. These cells seem to be limited to the acute phase of measles.