CD19: Lowering the Threshold for Antigen Receptor Stimulation of B Lymphocytes

• Published in: Science (American Association for the Advancement of Science) Vol. 256; no. 5053; pp. 105 - 107
• Main Authors: Carter, Robert H., Fearon, Douglas T.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for the Advancement of Science 03.04.1992; American Association for the Advancement of Science
• Subjects: Animals; Antibodies; Antibodies, Monoclonal - immunology; Antigen receptors; Antigens; Antigens, CD - genetics; Antigens, CD - immunology; Antigens, CD19; Antigens, Differentiation, B-Lymphocyte - genetics; Antigens, Differentiation, B-Lymphocyte - immunology; B cells; B lymphocytes; B-Lymphocytes - immunology; Biological and medical sciences; Cell growth; Cell Line; Cell proliferation; Cells, Cultured; Cultured cells; DNA Replication; Fundamental and applied biological sciences. Psychology; Fundamental immunology; Humans; Immunobiology; Kinetics; L cells; L Cells (Cell Line); Lymphocyte Activation; Lymphocytes; Lymphoid cells: ontogeny, maturation, markers, receptors, circulation and recirculation; Membrane proteins; Mice; Receptors, Antigen, B-Cell - immunology; Recombinant Proteins - immunology; T lymphocytes; Thymidine - metabolism; Antigen; Human; Membrane receptor; Crosslinking; Activation; B-Lymphocyte; IgM; Threshold
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1373518

Lymphocytes must proliferate and differentiate in response to low concentrations of a vast array of antigens. The requirements of broad specificity and sensitivity conflict because the former is met by low-affinity antigen receptors, which precludes achieving the latter with high-affinity receptors. Coligation of the membrane protein CD19 with the antigen receptor of B lymphocytes decreased the threshold for antigen receptor-dependent stimulation by two orders of magnitude. B lymphocytes proliferated when approximately 100 antigen receptors per cell, 0.03 percent of the total, were coligated with CD19. The B cell resolves its dilemma by having an accessory protein that enables activation when few antigen receptors are occupied.