Distribution and mobility of the A, D and c antigens on human red cell membranes: studies with a gold-labelled antiglobulin reagent.

Studies are presented in which a gold-labelled anti-IgG reagent has been used to map the distribution of A, D and c antigen sites on the human red cell membrane. Red cells were combined with IgG antibodies; ghosts were produced which were then labelled with gold-anti-IgG. D antigen sites were found to be single entities dispersed on the red cell membrane of lysed but otherwise untreated Rh positive cells. Following papain treatment prior to lysis, a clustered distribution was observed. Clustering of D sites was also observed on non-enzyme-treated red cells of the -D- phenotype. Further studies indicated that D and c antigen sites are closely associated on ccDEE red cells. The distribution of A antigen sites was found to be clustered in proportion to the amount of IgG anti-A combined with the cells. Reasons are given for considering such distribution as indirect evidence of mobility of A sites. There was an association between agglutinability of red cells by IgG antibodies and the extent of the clustering of the antigen sites.