Increase of circulating CD8+CD57+ lymphocytes after measles infection but not after measles vaccination.

Natural measles virus infection is recognised to induce immunosuppression, contributing to an increased susceptibility to other infections. A cell population that could be involved in this process is the CD8CD57 double-positive lymphocyte subset (CD8+CD57+), known to be significantly expanded in some viral infections, e.g. human immunodeficiency virus (HIV) infection. We therefore studied the level of CD8+CD57+ lymphocytes during measles infection and measles vaccination. Twenty-two measles patients were examined 5-57 days after the onset of fever and several months later. Healthy, age-matched controls were examined twice. Eleven children receiving measles-mumps-rubella (MMR) vaccination were examined before, 9-19 days and 5-9 months afterwards. Blood samples were analysed for the proportion of peripheral blood mononuclear cells carrying both CD8 and CD57, and for other cell surface markers (CD4, CD14, CD3, CD16(CD56) or CD20). Elevated proportions of CD8CD57 double-positive cells were found in the peripheral blood of children with natural measles early after infection (p < 0.05), whereas the proportion of other cell surface markers remained stable. No corresponding change in CD8+CD57+ lymphocytes was noted in MMR-vaccinated children or in healthy controls. Since CD8+CD57+ lymphocytes could be related to the immunosuppression seen in some viral infections, our finding of elevated CD8CD57 double-positive lymphocytes during acute measles infection would suggest that this population of lymphocytes is involved in measles-induced immunosuppression. The absence of an increase of CD8CD57 in children vaccinated with the conventional live attenuated measles vaccine, in contrast to children with natural measles infection, would thus indicate that the vaccine does not induce immunosuppression as measured in our in vitro system.