MONOCLONAL-ANTIBODIES AGAINST KELL GLYCOPROTEIN - SEROLOGY, IMMUNOCHEMISTRY AND QUANTIFICATION OF ANTIGEN SITES

Monoclonal antibodies BRIC 18, BRIC 68, BRIC 107 and BRIC 203 recogniz e high-frequency epitopes absent from erythrocytes expressing the K(o) phenotype. BRIC 107 has anti-k (K2)-like specificity. BRIC 203 has a unique specificity denoted anti-Kp(bc). All four monoclonal antibodies identify an M(r) 95 600 erythrocyte membrane protein by immunoprecipi tation from radio-iodinated erythrocytes. In quantitative binding stud ies using IgG it is estimated that there are from 2000 (BRIC 18) to 40 00 (BRIC 68) copies of the Kell glycoprotein per erythrocyte. Using Fa b fragments the estimates are in the range 4000 (BRIC 18) to 18 000 (B RIC 68) copies. In competitive binding assays the four epitopes define d by the BRIC monoclonal antibodies fall into two non-overlapping grou ps. The first group comprises BRIC 18, BRIC 68, BRIC 203 and an antibo dy (6-22) with anti-K14 specificity. The second group contains BRIC 10 7 and two further anti-k-like monoclonal antibodies (BS45 and OSK5). T he results suggest that the polymorphisms encoded at the K/k and Kp(a) /Kp(b)/Kp(c) loci may be located in two spatially distinct regions of the Kell glycoprotein(s).