Severe combined immunodeficiency with disbalance and functional abnormalities in the T-lymphocyte subsets

Abstract The case of an infant female with severe infections and failure to thrive is reported. Immunological workup demonstrated a severe combined immunodeficiency with normal numbers of circulating T and B lymphocytes. Studies of T-cell subsets showed an absence of T 8 + cells, while the percentage of T 4 + exceeded that of T 3 + cells. Functional studies of the T 4 + subset demonstrated lack of helper activity. When cocultured with normal T cells, B cells from the patients produced in vitro subnormal amounts of IgM, but practically no quantities of IgG and IgA. A lymph node biopsy showed a preserved T-cell-dependent area. Possible pathogenetic mechanisms are discussed.