Raillietina cesticillus: rejection by bursa-deficient chickens.

Chickens in which antibody-forming capacity was abrogated by bursectomy and irradiation developed protective immunity against Raillietina cesticillus as effective as controls which had specific antiworm antibodies in their sera and immunoglobulin positive cells in splenic and intestinal tissues. It is concluded that antibodies are not essential for the rejection of the tapeworm by chickens and may even retard rejection.