Characterization of the role of mononuclear cell subpopulations in the in vitro lymphocyte proliferation assay.

Purified human mononuclear cell subpopulations have been evaluated in the in vitro lymphocyte proliferation assay. Monocyte-depleted mononuclear cells had reduced or absent responses to mitogens and antigens which could be restored to the original mononuclear cell response by addition of purified plastic adherent cells. Purified T lymphocytes obtained by density gradient centrifugation of E-rosette-forming cells demonstrated low but significant proliferative responses to mitogens, but no significant response to antigens. The addition of monocytes potentiated the response of purified T cells to mitogens and antigens, but did not fully reconstitute the original mononuclear cell response unless non-T lymphocytes were also present. It is concluded that mononuclear cell proliferation represents a complex mechanism of cellular interaction involving multiple subpopulations of cells.

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.