Immunological changes after long-term feeding of germfree piglets with protein isolates and yeast cell walls from Candida utilis as food additives.

Germfree piglets were fed a diet supplemented with cell walls and a protein isolate from Candida utilis for 54 days. Besides morphological signs of activation of the lymphoid tissue which occurred primarily in the intestine of piglets which had been fed yeast cell walls, even an increased serum immunoglobulin level could be detected. In sera and intestinal content of piglets fed both with cell walls and isolated protein, specific antibodies capable of agglutinating yeasts were present. Even though a limited number of experimental animals was employed it can be concluded that the yeast material added to the diet elicited an immune response.