Reduced incidence of Marek's disease gross lymphomas in T-cell-depleted chickens.

Chickens of line 7, highly susceptible to Marek's disease (MD), were depleted of T-cells by neonatal thymectomy, total-body gamma-irradiation, and multiple injections with antithymocyte serum. In two replicate experiments, significantly fewer gross lymphomas were present in T-cell-depleted chickens than in intact or in T-cell-depleted, reconstituted hatchmates; these findings provided evidence that T-cells may be the principal target for MD virus (MDV) transformation, T-cell depletion was not complete, and the presence of microscopic lesions in T-cell-depleted chickens was attributed to residual T-cells. Ten lymphomas from intact chickens and 2 lymphomas from a T-cell-depleted chicken were examined for cellular composition. All lymphomas consisted predominantly of T-cells. The results of this and other published studies indicated that T-cells may have a dual role in MD; They may serve as a target for lymphoma formation by MDV and also may participate in immune surveillance against the disease in resistant chickens.