T and B cell defects in common variable immunodeficiency.

More than 50 patients with common variable immunodeficiency have been classified into 5 groups representing different blocks in B cell function. To do this, B cells were assessed in vitro by secretion of IgM or IgG in response to anti-IgM and IL-2 or to EBV alone. Some clinical features and the patients' sex ratio correlated with this B cell classification. In vitro attempts were made to identify and overcome these blocks using physiological ligands (e.g. cytokines), and agents that induce transcription (e.g. retinoic acid). The patient group with the most severely affected B cells also contained some patients whose T cells showed depressed DNA synthesis in response to mitogens. In vitro data indicate that the abnormality may be in the T cell itself rather than in monocytes failing to provide essential cytokines (e.g. IL-6). In 3 patients, splenic B cells were able to secrete IgM more effectively than circulating B cells, but still they produced no IgG.