Demonstration of immunoglobulin m on avian lymphoid leukosis lymphoma cells by the unlabelled antibody peroxidase‐antiperoxidase method

A series of 12 avian lymphoid leukosis and nine Marek's disease lymphomas from experimental and natural infections were studied for the demonstration of immunoglobulin M and Marek's disease tumour-associated surface antigen by the unlabelled antibody peroxidase-antiperoxidase method using impression smears and formaldehyde-fixed paraffin-embedded tissue sections. Results indicate that immunoglobulin M, the characteristic antigenic marker of avian lymphoid leukosis virus-induced B cell lymphomas, can be detected not only on tumour imprints but also in deparaffinised tissue sections. Of 12 chickens with proven lymphoid leukosis lymphomas, 10 were clearly diagnosed by demonstration of a predominance of immunoglobulin M-bearing cells in the lesions. Negative results of samples from two birds were due to unknown reasons or to post mortem deterioration of tissues. This technique is compatible with the routine histological tissue-processing, thus providing a specific complementary diagnostic tool for the identification of lymphoid leukosis lymphomas. Marek's disease tumour-associated surface antigen, the specific antigenic surface marker of Marek's disease tumour cells, was demonstrated only in one case using tumour imprints, but in no case with paraffin sections. This could possibly be due to the low frequency of this antigen in the lesions or to the loss of its antigenicity during the procedure used.