The phylogeny of macrophage function: Antigen uptake and degradation by peritoneal exudate cells of two amphibian species and CAF 1 mice

Abstract

Equal numbers of thioglycollate mobilized peritoneal exudate cells (PEC) of the newt, Notophthalamus viridescens, the South African clawed toad, Xenopus laevis, and CAF 1 mice were compared with respect to their capacity to take up and degrade soluble 14C-ovalbumin (OVA). PEC of the newt failed to take up the labeled antigen, while those of the toad incorporated only one-half as much as those of the mice. Moreover, the toad PEC degraded only 42% of the immunogen which was taken up, while PEC of the mice degraded 78% of the immunogen they had ingested during the 60-min period. Paraformaldehyde treatment of the PEC prevented antigen uptake, while chloroquine treatment prevented degradation with both species, and thus, active processes were involved. While newt PEC were unable to ingest soluble OVA, they were able to ingest and degrade OVA conjugated to sepharose during the same time period. The failure of primitive vertebrates to respond immunologically to soluble proteins appears to be due to their failure to ingest soluble immunogen.