Immune deficiency of T system with possible T cell regulatory activity defect.

The occurrence of T system immunodeficiency in an infant together with excessive production of IgM and, to a lesser degree, of IgG and IgA, is an unusual combination. A case is reported in which an unremitting lung infection with lymphadenopathy and hepatosplenomegaly developed in a previously healthy two-month-old infant. Leukocytosis with lymphocytosis, monocytosis and eosinophilia was rapidly followed by leukopenia and lymphocytepenia after a blood transfusion for anemia. There was a transient clinical remission, but on relapse 10 days later, quantitative and functional T cell deficiency was found together with increased IgG and IgA and with IgM values reaching 50 times greater than normal. Thymic humoral factor was successful in vitro in increasing the number of identifiable T cells (E rosetts) as well as T cell function (leukocyte migration inhibition factor production). However, the infant died suddenly, and at autopsy evidence of a generalized inflammatory reaction compatible with a viral infection was found. The thymus was small, hypoplastic and hypocellular. It is speculated that the T system deficiency may have been acquired following Epstein-Barr virus infection, and that T cell regulatory activity of immunoglobulin production was defective.