Protein absorption by blood corpuscles

If 1 per cent. goat serum is added to freshly drawn defibrinated normal rabbit blood, the mixture incubated for one hour, and then separated by centrifugation into serum and corpuscle fractions, a titration of the serum fraction by specific precipitin methods will usually show but 25 per cent. of the goat protein originally added to the blood.

If the serum and corpuscle fractions so obtained are allowed to undergo independent autolysis (10 hrs., 37° C), a distinct restoration of the goat protein is observed in each fraction. The restoration of the protein in the corpuscle fraction, however, is usually much more pronounced than that in the serum fraction, and may amount to as much as 50 per cent. of the total protein originally added to the blood.

If goat serum is slowly injected intravenously into normal rabbits in amounts not exceeding 1 per cent. of the total blood volume, and blood is withdrawn from 1 to 4 hours later, a distinct restoration of the goat protein can be brought about by allowing the centrifuged but unwashed corpuscles so obtained to undergo autolysis.

Parenterally introduced proteins, therefore, are apparently absorbed in large measure by the circulating blood corpuscles.