Immunoglobulin synthesis in vitro by lymphocytes from patients with immune deficiency: requirements for a special serum factor

Certain patients with immune deficiency were encountered whose peripheral blood lymphocytes included no immunoglobulin-bearing cells. However, other markers of B type lymphocytes were observed; lymphocytes isolated free of macrophages showed the presence of receptors for the Fc fragment of IgG and for the third component of complement. One patient with a syndrome of thymoma and severe hypogammaglobulinemia was studied 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 serum; in media supplemented with autologous serum, the cells developed no surface Ig. During culturing antigenic determinants of immunoglobulin 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 lymphocytes 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 immunoglobulin 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.