ABNORMAL LYMPHOCYTE CAPPING IN A PATIENT WITH SEVERE COMBINED IMMUNODEFICIENCY DISEASE

Despite the presence of normal numbers and distribution of T and B lymphocytes and normal levels of serum immunoglobulins, a five-month-old infant failed to show any evidence of T-cell or B-cell immunity. In trying to identify a specific membrane abnormality as a potential cause of the immunologic dysfunction, we examined the lateral mobility of the cell-surface receptor for concanavalin A. In contrast to normal cells, in which the receptor is distributed uniformly over the cell surface, the patient's lymphocytes showed an unusually high accumulation of concanavalin A receptors in surface caps. This capping abnormality appeared in both T and B lymphocytes and was exaggerated by colchicine, an inhibitor of microtubule assembly. These findings support the theory that plasma-membrane-cytoskeleton interactions have a role in the expression of specific immunity; the findings also identify new areas that should be considered in trying to understand the primary immunodeficiency diseases. (N Engl J Med 301:1245–1249, 1979) SEVERE combined immune deficiency (SCID) is a heterogeneous and uniformly fatal disorder characterized by the failure of specific humoral and cellular immunity to develop.1 2 3 4 With rare exception,5,6 it presents with a marked impairment in the expansion of cells of T lineage; normal numbers of peripheral blood lymphocytes and, indeed, elevated numbers of B lymphocytes often prevail, despite the uniform presence of profound hypogammaglobulinemia. Thus, the combined deficiency often reflects the failure of T-precursor cells to mature; they show arrests at various stages of development, including a primary failure of function of thymic epithelial cells.3,4 We report on an infant with. © 1979, Massachusetts Medical Society. All rights reserved.