Abstract
Spleen cells from chickens inoculated 7 to 8 days previously with Marek's disease virus were cytotoxic for 51Cr-labeled cells of a Marek's disease lymphoblastoid cell line (MSB-1 line) in a 4-h in vitro cytotoxic assay. The cytotoxic activity of spleen cells was inhibited by pretreatment with antithymocyte serum and complement, but not with complement alone or in combination with anti-bursa cell serum or normal preimmune serum. The conclusion was that the effector cell in the above cytotoxic assay was a thymus-derived lymphocyte. Also, pretreatment of target cells with Vibrio cholerae neuraminidase enhanced in vitro cytotoxic activity of effector cells. Similar enzymatic treatment of effector cells had a negligible effect on cytotoxicity.