Uptake and catabolism of antigen by alvelar macrophages of dogs with respiratory hypersensitivity. Processing of antigen by alveolar macrophages.

The ability of alveolar macrophages of dogs to bind and metabolize two antigens was studied. The antigens were ragweed antigen E (AgE) and keyhole limpet haemocyanin (KLH). These antigens were chosen because of the availability of dogs with respiratory hypersensitivity to them and because they are of very different molecular weights. It was shown that: (1) antigen processing was identical using macrophages from hypersensitive as compared with normal dogs; (2) in comparison with AgE, much more of the higher molecular weight antigen, KLH, was bound to macrophages and much less degraded during subsequent incubation, leaving a greater proportion of the antigen bound to the cell membrane; (3) respiratory cells which had taken up AgE at 0 degrees C instead of 37 degrees C and were then incubated at 37 degrees C were much more active in catabolizing bound antigen with consequently less membrane bound antigen remaining; (4) increases in catabolism of bound AgE were also found in cells from relatively recently lavaged animals; (5) there was no evidence that cytophilic antibody contributed to the uptake of AgE.