Lymphocyte subpopulations and responsiveness in rats bearing intracranial tumors induced by avian sarcoma virus.

The mitogenic responsiveness of peripheral blood lymphocytes obtained from Fischer 344 rats inoculated with avian sarcoma virus was studied. In addition, quantitative alterations in lymphocyte subpopulations were determined in these animals. Only peripheral blood lymphocytes from rats bearing astrocytomas had significantly diminished responses to concanavalin A when compared to control responses. The percentage of lymphocyte subpopulations detected in either the peripheral blood or spleen of tumor-bearing rats did not differ from values obtained with control rats. However, rats bearing astrocytomas had a marked decrease in the absolute number of the various lymphocyte subpopulations as a result of lymphopenia. Neither the sarcoma-bearing rats nor the virus-inoculated rats that did not develop tumors exhibited this lymphopenia. In addition, sera from rats bearing astrocytomas diminished the concanavalin A reactivity of spleen cells obtained from normal rats. The results of this study establish the avian sarcoma virus-induced rat astrocytoma model as a useful immunological parallel for the human disease.