H-2 expression by lymphoid cells of different mouse strains: quantitative interaction of H-2 with monoclonal antibodies and their Fab fragments.
Monoclonal antibodies (H100-30/3 and 11-4.1) to H-2k were used to study H-2 antigen expression and characteristics of the H-2 antigen-antibody interaction at the cell surface. Studies with radiolabelled F(ab')2 and Fab' fragments of 11-4.1 antibody confirmed that monoclonal IgG binding to cells is directly proportional to the number of H-2 sites and shows a high proportion of monovalent binding over a wide range of concentrations. Scatchard plots showed no difference in the binding affinity constant (Ka) of a given monoclonal antibody on lymphoblasts from various H-2k F1 and congenic strains, but only in the number of antigenic sites per cell. F1 (k x d) lymphoblasts show 1 x 10(5) H-2k sites/cell, about 50% of the expression in homozygotes. Dk expression in C3H.OH is 1.4 x 10(4) sites/cell. While normal cells appear to have a constant amount of H-2 (2-3 x 10(5) sites/cell), BW thymoma cells show unstable H-2 expression, having an average of five times fewer H-2 sites per cell when grown in vitro as compared to in vivo growth. Another BW cell surface marker, Thy-1.1, does not fluctuate in parallel with H-2. The 30/3 and 11-4.1 antibodies bind to topologically distinct sites on H-2Kk. The binding of these antibodies can be perturbed differentially: paraformaldehyde fixation of cells abolishes binding of 11-4.1 antibody but not of 30/3 antibody; increasing temperature increases the Ka of 30/3 antibody binding but decreases the Ka of 11-4.1 antibody binding to cells.
D000818:Animals; D000937:Antigen-Antibody Reactions; D001666:Binding Sites, Antibody; D002478:Cells, Cultured; D006183:H-2 Antigens / Q000276:immunology*; D006358:Hot Temperature; D007140:Immunoglobulin Fab Fragments / Q000276:immunology*; D007074:Immunoglobulin G / Q000276:immunology; D008214:Lymphocytes / Q000276:immunology; D051379:Mice; D008815:Mice, Inbred Strains; D009374:Neoplasms, Experimental / Q000276:immunology; D013945:Thymoma / Q000276:immunology
D006183:H-2 Antigens; D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G