Expression of Lymphocyte Differentiation Antigens in Immunodeficiency Diseases

Immunodeficiency diseases are frequently caused by defects in lymphocyte differentiation resulting in inadequate synthesis of immunoglobulin (Ig) or the lack of antigen-specific antibodies (1). The failure of B cells to differentiate into plasma cells results from either inherent B cell defects, the selective absence of helper T cell activity, excessive suppressor T cell activity, or Epstein—Barr virus infection (2,3). The most common deficiency is the failure of IgA production. Patients with selective IgA deficiency (IgA-) have B cells of normal phenotypes except their IgA B cells are immature and coexpress surface IgM (4). In addition, these patients may be concomitantly deficient in other IgG isotypes (5). Patients with common variable immunodeficiency (CVI) have normal numbers of B and T cells of normal phenotypes, but few if any plasma cells (6). Similarly, X-linked immunodeficiency (XLA; X-linked agammaglobulinemia) results from abortive B cell differentiation. Males with this disease form normal numbers of bone marrow pre—B cells, but are deficient in B cells and plasma cells (7). The frequency of circulating B cells is 100-fold lower than that in normals, but the T cell lineage appears to be unaffected since cell-mediated immunity is intact and circulating T cells and T cell subsets are normal in number, proportion, and function. Patients with acquired immunodeficiency disease syndrome (AIDS) have a preferential loss of helper T cells that results in suppression of T cell function (8).