INTESTINAL UPTAKE OF MACROMOLECULES .6. UPTAKE OF PROTEIN ANTIGEN INVIVO IN NORMAL RATS AND IN RATS INFECTED WITH NIPPOSTRONGYLUS-BRASILIENSIS OR SUBJECTED TO MILD SYSTEMIC-ANAPHYLAXIS

Abstract

Adult Sprague-Dawley rats weighing approximately 250 g were fed bovine serum albumin [BSA] and NaH CO3 by gavage. Serum was obtained at intervals after feeding and tested for immunoreactive bovine serum albumin by radioimmunoassay. Nanogram amounts of immunoreactive BSA were detected in serum; peak values were obtained after 4-6 h. The influence of intestinal inflammation on protein uptake was examined in 2 model systems. Infection of rats with N. brasiliensis was accompanied by partial villous atrophy in the intestinal segments harboring adult worms and mild systemic anaphylaxis in the rat was accompanied by increased intestinal vascular and mucosal permeability. Enhanced uptake of BSA was observed before and shortly after self-cure of infection and during mild systemic anaphylaxis. The molecular size of immunoreactive BSA approximated that of the administered BSA; no small fragments of BSA-bearing antigenic determinants were detected.