Red cell Fc receptors and their participation in the passive haemagglutination mediated by non-precipitating antibodies

Abstract

A study has been made of the fixation to sheep, rabbit, guniea-pig and human red cells (both untreated and trypsin-treated cells) brought about by different non-precipitating antibodies and their corresponding F(ab′)₂ fragments, as well as by human IgG and its corresponding fragments F(ab′)₂, Fab and Fc.

The results obtained with the antiglobulin test seem to indicate that there exists on the surface of the red cells Fc receptors which exhibit a greater affinity for the Fc fragment which has undergone structural changes consequent upon either the immunoglobulin-binding interaction or as a result of enzymic degradation.

The Fc receptors would appear to be superficial in the majority of animal species studied. In the case of human red cells their liberation depends upon prior treatment with trypsin

On the basis of these investigations consideration should be given to the theory that the passive haemagglutination mediated by non-precipitating antibodies could be of the mixed type, with the participation of both Fab and Fc fragments.