Deficiency of ,c- or A-type Immunoglobulins

A marked imbalance of the two light chain types of immunoglobulins was observed in two young male adults suffering from primary hypogammaglobulinemia and intrinsic factor-deficient pernicious anemia. In one patient, the i/A light chain ratio of serum immunoglobulins was 0.01; in the other it was approximately 6 (normal value, 1.8± 0.3). This light chain imbalance was found within each of the three main immunoglobulin classes. The number of mature immunoglobulin-producing cells in the bone marrow and in the mucosa of the gastrointestinal tract was reduced. The relative frequency of x- and A- producing cells in these tissues corresponded to the ic/A ratio of serum immunoglobulins. However, the number of peripheral lymphocytes with membraneassociated immunoglobulins as well as the percentage distribution of blood lymphocytes with ic- or A-type immunoglobulins on the membrane were within normal limits inboth cases. The results suggested a hitherto unknown defect in the maturation of B-cells leading to an abnormal ratio of ic- and A-type immunoglobulin-secreting cells. N ORMAL HUMAN immunoglobulinsare classified in five heavy chain classes and two light chain types. A number of characteristic, nonspecific biologic properties are associated with the constant part of the various heavy polypeptide chains. Nothing is known, on the other hand, about the biologic significance of the constant part of the light polypeptide chains. About 65% of the immunoglobulins in the serum of normal adults are of the K-light chain type, and 35% is of the A-light chain type (K/A ratio = 1.8 ± 0.3’). Physiologic variations of the K/A ratio occur in infancy.’ Moderate imbalances may be found in primary immune deficiency disorders.”2 Marked imbalances are rarely seen: Bernier et al.3 have observed a young girl with recurrent infections presenting with a defective K-type immunoglobulin synthesis and decreased IgG and IgE serum levels. In this report, results of investigations in two additional cases are presented: one with a deficiency of K-, the other with a deficiency of