Free immunoglobulin light chain synthesis by lymphocytes from patients with hypogammaglobulinaemia.

Lymphocytes from six individuals with reduced or deficient serum immunoglobulins of one or more class were assessed for immunoglobulin production in vitro. There was no clinical evidence of a secondary cause for hypogammaglobulinaemia and three of the cases were receiving immunoglobulin therapy. The predominant immunoglobulin product in the culture supernatants form four cases was free light chain. In contrast, peripheral lymphocytes from two cases with partial IgA deficiency and from normal individuals exhibited a balanced synthesis of heavy and light chains. These findings are discussed with particular reference to free light chain synthesis by immature neoplastic B lymphocytes and to normal B lymphocyte differentiation.