Lymphocyte transformation, interferon, and leukocyte migration inhibition factor synthesis were studied in purified lymphocyte cultures for 20 children with congenital rubella and 18 healthy children (seven susceptible and 11 immune to rubella). Lymphocyte transformation after phytohemagglutinin stimulation was significantly lower in children with congenital rubella as compared to healthy controls. Responses to purified rubella virus were absent in the susceptible controls and absent or at least two times lower in congenital rubella children than in immune controls. After purified rubella virus stimulation, leukocyte migration inhibition factor production was detected in all immune controls, but in none of the susceptible controls, or the congenital rubella-infected children. The results varied with gestational age of intrauterine infection: the impairment of cellular immune response, both after phytohemagglutinin or rubella virus stimulation, was more severe in the children infected in the first two months than in the latter stages of gestation.
