Cell-mediated and humoral immunity to mumps virus antigen.

In the present study, cell-mediated and humoral immunity to mumps virus was investigated. The study population consisted of 25 subjects of whom 17 were initially seropositive for mumps. Serum antibody levels and lymphocyte blast transformation activity were measured before and after vaccination with inactivated vaccine. In addition, the subjects were skin tested and HLA-typed. Significant antibody responses, measured by enzyme-linked immunosorbent assay (ELISA), were observed after vaccination in all immunoglobulin classes. However, the elevation in antibody levels was usually transient in both seronegative and seropositive subjects. The IgA response was significantly higher in the seropositive than in the seronegative group, but no such difference was found in IgM or IgG antibodies. Vaccination also caused a significant but transient rise in lymphocyte blast transformation activity. Transformation results parallelled skin-test results and seropositivity, but not antibody levels, in the seropositive group. Pronounced IgA reactivity was significantly associated with Dw3 and Dw4 (DR3 and DR4) antigens. No HLA association was observed in IgG or IgM levels or in transformation activity.