Induction of Immunoglobulin Secretion and DNA Synthesis in Human Lymphocytes in Vitro by Cytomegalovirus Preparations

Abstract

Immunoglobulin secretion as evidenced by plaque-forming cells (PFC) in an indirect haemolysis-in-gel assay, and DNA synthesis were induced in human blood lymphocytes by the following preparations of cytomegalovirus (CMV): Nucleocapsid Nc-CMV antigen, membrane M-CMV antigen, crude C-CMV preparations and CMV-incubated adherent cells. Peak stimulations occurred around day 6 in culture. Nc-CMV and M-CMV only stimulated PFC and DNA synthesis in lymphocytes from CMV seropositive individuals. C-CMV also stimulated lymphocytes from CMV seronegative individuals but gave better responses in lymphocytes from CMV seropositive individuals. CMV-incubated adherent cells occasionally stimulated lymphocytes from CMV seronegative individuals but always in CMV seropositive blood donors. Nc-, M-, and C-CMV gave high numbers of PFC in B cells enriched by sheep erythrocyte sedimentation and in co-cultures of enriched T and B cells. Almost no PFC were induced in enriched T cells. DNA synthesis induced by all the three antigenic CMV preparations increased after removal of adherent cells. Strong DNA synthesis was induced in enriched T cells compared to almost none in enriched B cells. It is concluded that some pure CMV preparations act as antigens and more crude preparations induce polyclonal activation. Different CMV preparations may be used to diagnose CMV, to study immune reactivity against CMV and as a model for CMV infections in vitro.