Validation of an immunocytochemical assay for immunophenotyping of lymphoma in guinea pigs (Cavia porcellus)

Background Lymphoma is an important disease of pet guinea pigs, although validation of immunophenotyping techniques based on cytologic or hematologic samples has not been reported. Objective To describe an immunocytochemical method for immunophenotyping of lymphoma (as either T- or B-cell) in guinea pigs, and to validate antibodies for this purpose. Methods Blood and tissues were obtained at the time of necropsy from laboratory guinea pigs and a privately owned dog (control) euthanized for reasons unrelated to lymphoproliferative disease. Fine-needle aspirates of enlarged peripheral lymph nodes were obtained from a case of spontaneous lymphoma in a pet guinea pig. Anti-CD3 and anti-Pax5 antibodies were validated by a combination of western blotting performed on splenic lysates of both the dog and guinea pigs, immunohistochemical studies on normal guinea pig tissues, and immunocytochemistry on normal guinea pig peripheral blood and splenic impression smears. Results The antibodies bound to antigens of an appropriate size in both the dog and guinea pig splenic lysates by Western blot analysis. Immunohistochemistry and immunocytochemistry demonstrated the expected distribution of putative T- and B-lymphocytes in normal tissues, peripheral blood, and splenic impression smears. As a proof-of-principle for its clinical utility, this immunocytochemical assay was used to diagnose a B-cell phenotype in a spontaneous lymphoma case in a pet guinea pig. Conclusions Here, we validated an immunocytochemical method for immunophenotyping of lymphoma in guinea pigs as either a T- or B-cell phenotype. This enables future research into the clinical attributes of these subtypes and may ultimately improve both prognostication and therapy of lymphoma in guinea pigs.