IMMUNOLOGICAL STUDIES OF A HORSE WITH LYMPHOSARCOMA

Immunological, clinical, and pathological investigations were conducte d on a horse with lymphosarcoma. The immunological status was investig ated by measuring the level of antibodies by single radial immunodiffu sion test and the ability of lymphocytes to proliferate in response to mitogens. Multiple immunological abnormalities were noted in this hor se. They were; (1) decreased IgM, IgG, and IgA levels in the serum des pite hyperproteinemia; (2) increased in-vitro spontaneous lymphoprolif eration which reflects augmented mitosis; (3) decreased lymphoprolifer ative response to T cell stimulants (e.g. Concanavalin-A (Con-A)) sugg esting impaired T cell activation; (4) presence of immunosuppressive f actors in serum as demonstrated by in-vitro lymphocyte culture systems . Clinical pathology findings revealed an unusual monoclonal alpha pea k in the serum and morphologically abnormal lymphocytes distributed th roughout the body. Serum fractionated by fast protein liquid chromatog raphy (FPLC) revealed that the immunosuppressive factors were found in this abnormal alpha peak. The immunopathological findings in this hor se are discussed.