Specific cell-mediated immune defect in active cytomegalovirus infection of young children and their mothers.

4 young children with active cytomegalovirus (C.M.V.) infection were found, by an in-vitro lymphocyte-proliferation assay, to have a C.M.V.-specific cell-mediated immune defect. These children had antibodies to C.M.V. and were actively shedding C.M.V. in the urine when studied. Their general cellular immune responses were intact, with normal numbers of T lymphocytes and normal in-vitro responses to mitogens and at least one antigen. 3 of the 4 mothers studied shortly after delivery had decreased cell-mediated immunity to C.M.V. These findings suggest that an antigen-specific immune defect facilitates transmission of virus from mother to infant and permits persistence of viral replication in the offspring.