Immunoglobulin Synthesis In Vitro by Lymphocytes from Patients with Immune Deficiency: Requirement for a Special Serum Factor (B-cell markers/B-cell differentiation/serum factor/T-cell influence/mitogen action)

Certain patients with immune deficiency were encountered whose peripheral blood lymphocytes in- cluded no immunoglobulin-bearing cells. However, other markers of B type lymphocytes were observed; lymphocytes isolated free of macrophages showed the presence of re- ceptors for the Fc fragment of IgG and for the third com- ponent of complement. One patient with a syndrome of thymoma and severe hypogammaglobulinemia was stud- ied in special detail. In vitro the patient's cells were able to develop surface Ig in media supplemented with fetal-calf serum or normal human seruin; in media supplemented with autologous serum, the cells developed no surface Ig. During culturing antigenic determinants of immuno- globulin became detectable in the medium, and both medium and cell-surface immunoglobulin underwent a shift from specific IgM determinants early in the culture period to IgG and IgA determinants later. Normal lym- phocytes and thymocytes activated by concanavalin A repaired the deficiency in the patient's serum. These data support the concept that a factor possibly derived from T cells is missing from this patient's serum and that this factor is required for the maturation of the B cell for im- munoglobulin synthesis. A patient with X-linked agammaglobulinemia had a population of circulating lymphocytes with some surface characteristics that appeared similar to those of the B cells from the patient with thymoma. In contrast, however, no Ig synthesis by this patient's cultured cells could be demonstrated. The possible nature of the lymphocytes reacting with aggregated IgG in this case is discussed. During the course of studies on the lymphocytes of a variety of patients with immunodeficiency, two special patients were investigated in particular detail because of an absence of im- munoglobulin (Ig)-bearing peripheral blood lymphocytes (PBL), despite the presence of cells that carried receptors for aggregated human IgG; the latter, as well as surface Ig, have been shown to be B cell markers (1). The possibility arose that a population of abnormal nonimmunoglobulin-bearing B lymphocytes was present or alternatively that these cells represented a selective and excessive proliferation of the nor- mal subpopulation of lymphocytes (K cells) which also possess an Fc receptor and are involved in antibody-induced )ymph- ocyte-mediated killing of target cells (2, 3). Since one patient had a thymoma associated with the immune deficiency, it appeared of interest to ascertain whether a thymus defect was in some way involved in the occurrence of the unusual B cells Abbreviations: PBL, peripheral blood lymphocytes; B cells, bone marrow-derived cells; T cells, thymus-derived cells; FCS, fetal calf serum; Fc, a fragment of immunoglobulin G; PHA, phytohemagglutinin; LPS, lipopolysaccharide; con A, con- canavalin A. that were found. Therefore the patient's cells were put into culture, removed from their usual environment. When the cells were cultured in certain serum-containing media, but not when cultured in others, surface Ig did indeed develop, and antigenic determinants of immunoglobulin became detectable in the culture supernatants. It appeared that development of cell surface Ig depended upon a factor present in fetal-calf serum (FCS) and normal human serum but not in the serum of the patient. In contrast the second patient, with infantile X-linked agammaglobulinemia, failed to produce Igs in vitro under similar conditions.