C4 allotyping by prolonged gel electrophoresis and immunoblotting using monoclonal and polyclonal antibodies

Out of the 136 individual samples mostly from HLA-typed family members which were submitted to the VIth Complement Genetics Workshop 1989, Mainz, FRG, for C4 allotyping, 129 were analyzed by prolonged gel electrophoresis followed by immunoblotting. The blotting was performed using either a Rodger (Rg):1,2 specific monoclonal, 99H7 (provided by G. Mauff, Cologne, FRG), and/or a Chido (Ch):1 specific monoclonal antibody (MoAb), 2B12 (provided by G.J. O'Neill, Miami, USA), and a polyclonal antihuman C4 antibody. In addition, 29 individuals from the workshop panel were tested with a third antibody, 1217, and 20 individuals with a fourth antibody, 1228 (both provided by D. Bitter-Suermann, Hannover, FRG). Due to the improved typing technique a total of 13 C4A and 16 C4B variants could be discriminated, of which some have not yet been described. Considering as a rule that all allotypes with great hemolytic activity are named C4B, the Ch:1 specific antibody 2B12 is reactive with all B allotypes except C4*B11, C4*B12, C4*B13, some C4*B3, C4*B4, one C4*B5, and weakly with one C4*B6 variant. The Rg:1,2 specific antibody 99H7 recognizes all C4A allotypes except for C4*A91, one C4*A1, and some C4*A12 variants. Therefore all these allotypes mentioned may, like C4*A91, express reversed antigenicity. The two additionally tested MoAbs 1217 and 1228 reacted similar to 2B12 with one exception for each. Correlations of HLA haplotypes with C4 allotypes especially with those of reversed antigenicity are discussed.