In vitro leucocyte proliferative responses and lymphocyte sub-types in guinea pigs with genetically determined high- and low-level responsiveness to Trichostrongylus colubriformis

In vitro leucocyte proliferative responses to parasite antigens and to mito gens as well as lymphocyte sub-types were compared in guinea pigs with gene tically determined differences in their ability to express protective immun ity against Trichostronylus colubriformis infection. Proliferative response s to parasite antigens were greatest in high-responder (HR) animals, but ce lls from low-responder (LR) animals were generally more responsive to mitog ens. However, HR circulating leucocytes were more responsive to the T-cell- dependent B-cell mitogen pokeweed mitogen (PWM), and the response of HR, bu t not LR, cells increased during primary infection with T. colubriformis. F low cytometry revealed significantly greater numbers of circulating B-cells in HR animals and, as observed for responsiveness to PWM, the number of ci rculating B-cells increased in HR, but not LR, animals during primary infec tion with this parasite. These findings suggest a larger and more labile po pulation of B-cells in HR guinea pigs.