Lymphocytes and antibody in retrovirus-induced feline pure red cell aplasia

The possible role of antibody and T-lymphocytes was investigated in the pure red cell aplasia (PRCA) associated with feline leukemia virus, subgroup C (FeLV-C), infection. In previous studies, erythroid colony-forming cells were undetectable in marrow culture of cats with PRCA. Yet erythroid burst-forming cells (BFU-E) remained, suggesting that BFU-E were able to differentiate in vitro but not in vivo. It was inferred that immunologic suppression may contribute to the pathogenesis of feline PRCA, and the interactions of antibody and T-lymphocytes with erythroid and granulocyte-macrophage progenitors were studied. Incubation of normal or PRCA marrow cells with PRCA serum or IgG concentrated from this serum and then complement (C') failed to decrease hematopoietic colony growth when compared to the results obtained with cultures of marrow cells incubated with C' alone. In crossover coculture studies, T-cells from Safari cats with PRCA had no inhibitory effect on colony growth from normal or autologous PRCA marrow cells. For the determination of whether feline PRCAs were associated with a clonal T-cell process, lymphocytes were obtained periodically from glucose-6-phosphate dehydrogenase (Glc-6-PD) heterozygous cats following FeLV-C infection and were expanded with a crude preparation of interleukin-2. The ratios of Glc-6-PD enzyme types in these samples did not change as cats developed anemia, suggesting that the inhibition of erythropoiesis was not associated with the clonal expansion of T-cells. These studies, therefore, do not support the premise that feline PRCA results from the interaction of antibody or T-cells with erythroid progenitors.