Recognition of xenogeneic proteins by the blue crab: Dissociation of the clearance and degradation reactions and lack of involvement of circulating hemocytes and humoral factors

Abstract

Blue crabs clear foreign proteins from the circulation to the gills in a manner that can be explained by postulating the participation of a finite number of naturally occurring quasi-specific receptors. The rate of this clearance reaction is not increased by previous exposure to the foreign protein although recovery to the normal rate of clearance after high level blockade is quite rapid. The cleared foreign proteins are degraded in the gills in a relatively nonspecific fashion suggestive of a clear distinction between the clearance and degradation reactions. The results of perfusion experiments indicate that neither circulating hemocytes nor specific humoral factors are responsible for the foreign protein clearance reaction in blue crabs. Thus it is concluded that fixed cells, most likely in the gills, are responsible for this means of dealing with nonself proteins in blue crabs and possibly other crustaceae.