Induction of avian immunological responsiveness following cloacal drinking of immunogen.

A solution of human serum albumin which has been cloacally ingested can cause effective development of immunological memory with minimal or no immediate production of antibody in 4 to 6 week old chickens. Such memory production was not accompanied by the generation of circulating rosette-forming ABC (antigen binding cells) and thus the peripheral appearance of such cells as a part of the normal primary response to HSA (human serum albumin) does not accord with the interpretation that they represent memory B cells. The cloacal route may be important for the maturing chick in initiating immunity to the food and micro-organisms of its external environment and gut flora.