B cell differentiation and immunoregulatory T cell function in human cord blood lymphocytes.
The functional maturity of T and B lymphocyte populations from human newborns was evaluated using a reverse hemolytic plaque assay to detect immunoglobulin-secreting cells generated in in vitro cultures stimulated with pokeweed mitogen (PWM), a T cell-dependent polyclonal activator, and the Epstein-Barr virus (EBV), a T cell-independent B cell activator. Cord blood lymphocytes failed to produce immunoglobulin in response to PWM, but did respond with immunoglobulin synthesis to stimulation with EBV. Co-culture experiments demonstrated that cord blood T cells would inhibit immunoglobulin production by adult cells stimulated with PWM, but not with EBV. Cord blood T cells did suppress immunoglobulin production by cord blood B cells when stimulated with a mixture of EBV and PWM, indicating that cord blood, in contrast to adult blood, contains a population of suppressor T cell precursors that are easily activated by PWM. Irradiation of the cord blood T cells with 2,000 rad eliminated the suppressor activity and revealed normal helper function for immunoglobulin (Ig) G, A, and M when these T cells were co-cultured with adult B cells. Cord blood B cells co-cultured with adult T cells or irradiated cord blood T cells did produce immunoglobulin in response to PWM, but the response was significantly lower than that of adult B cells, and only IgM was produced in these cultures. These studies demonstrate that both the T and B cells of the human newborn have significant functional differences compared with the functions of T and B lymphocyte populations in adults.
D000917:Antibody Formation; D001402:B-Lymphocytes / Q000276:immunology*; D005312:Fetal Blood / Q000276:immunology*; D004854:Herpesvirus 4, Human / Q000276:immunology; D006801:Humans; D007108:Immune Tolerance; D007070:Immunoglobulin A / Q000096:biosynthesis; D007074:Immunoglobulin G / Q000096:biosynthesis; D007075:Immunoglobulin M / Q000096:biosynthesis; D008211:Lymphocyte Cooperation; D008934:Mitogens; D013601:T-Lymphocytes / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology
D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D008934:Mitogens