Immunologic significance of the mumps virus skin test in infants, children and adults.

The biologic validity of cell-mediated immunity to mumps virus was evaluated in 395 children, adolescents and adults. The study protocol included the determination of cutaneous delayed hypersensitivity to viral and avian control antigens and in 79% of the subjects an essential double bleeding was performed before and after mumps virus skin test for assay of neutralizing antibody. Seven per cent of subjects expressed sufficient delayed hypersentitivity to the control antigen to erase an apparently positive mumps virus skin test. Anamnestic conversions from seronegativity to seropositivity, elicited by the mumps virus skin test, increased from 4% in children to 25% in adults, which suggests waning B-cell recognition of prior mumps virus infection in adults. Although pregnancy diminished the difference (p smaller than .001), adults showed greater cutaneous delayed hypersensitivity to mumps virus antigen than did children (p smaller than .001), suggesting that mumps virus reinfection or persistence induced the escalation of more sensitive T-cell recognition with increasing age. Humoral immunity, assessed by the double bleeding technique in the vast majority of individuals, rose form 16% (1-4 years), 45% (5-9 years) and 80% (10-14 years) to 94% in adolescents and adults. Ordinarily 75-95% in other age groups, the decline of correlation between mumps virus cellular and humoral immunity to 60% in school children may result from prior parainfluenza virus infection, inconsistent potency of the skin test antigen, concurrent immunosuppressive infection, and lagging induction of mumps virus cellular immunity in recently infected individuals. Immunologic study of a large colony of subhuman primates failed to establish an hierarchial antigenic interrelationship among mumps virus and two additional paramyxoviruses.