CHARACTERIZATIONS AND IMMUNOTHERAPY OF FELINE RETROVIRAL (FELV) ASSOCIATED HEMATOPOIETIC MALIGNANCIES AND IMMUNODEFICIENCY: CLINICAL, IMMUNOLOGICAL AND PATHOLOGICAL STUDIES

Scope of Study. Efforts were undertaken to further characterize and attempt to remit through treatment the hematopoietic malignancies and the state of deficient immunity which develop subsequent to chronic retroviral, feline leukemia virus (FeLV), infection. The presenting status of cats with persistent retroviral infection were to be characterized, appropriate animals were to be treated by the extracorporeal perfusion of their plasma over purified staphylococcal protein A, and these cats monitored for changes from their pretreatment condition. In addition, attempts were to be made to further define the lymphoid cellular dysfunctions and depletions which are thought to contribute to the retroviral associated state of deficient immunity.;Findings and Conclusions. When cats with overt hematopoietic malignancy and chronic retroviral infection were treated with staphylococcal protein A, a proportion responded to treatment; their malignancies regressed and evidence of their retroviral infection diminished. Cats presenting with chronic retroviral infection and myelodyscrasias similarly responded to treatment and these clinical improvements were preceded by a transient increase in plasma interferon level and the appearance of an antibody directed toward the major retroviral envelope glycoprotein gp70. Cats with retroviral associated hematopoietic malignancy frequency presented with elevated serum calcium levels that were within or slightly above the upper limit of normal. The in vitro synthesis of interferon by normal feline lymphocytes was reduced when UV-inactivated FeLV was also present in the lymphoid cultures. A new lymphoma-derived FeLV-replicating cell line was isolated and found to lack surface characteristics of T and B-lymphocytes. Immunological assays and reagents were developed which will serve in future studies attempting to identify aberrations in T-lymphocyte function and number in the retroviremic cat.