H-2 EXPRESSION BY LYMPHOID-CELLS OF DIFFERENT MOUSE STRAINS - QUANTITATIVE INTERACTION OF H-2 WITH MONOCLONAL-ANTIBODIES AND THEIR FAB FRAGMENTS

  • 1 January 1981
    • journal article
    • research article
    • Vol. 42  (2) , 207-215
Abstract
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 radiolabeled F(ab'')2 and Fab'' fragments of 11-4.1 antibody confirmed that monoclonal IgG binding to cells is directly proportional to number of H-2 sites and shows a high proportion of monovalent binding over a wide concentration range. 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 .times. d) lymphoblasts show 1 .times. 105 H-2k sites/cell, about 50% of the expression in homozygotes. Dk expression in C3H.OH is is 1.4 .times. 104 sites/cell. While normal cells appear to have a constant amount of H-2 (2-3 .times. 105 sites/cell), BW thymoma cells show unstable H-2 expression, having an average of 5 times fewer H-2 sites/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.

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