DETECTION OF T-CELL AND B-CELL IN MANY ANIMAL SPECIES USING CROSS-REACTIVE ANTIPEPTIDE ANTIBODIES

A wide range of lineage-specific Ag are detectable in the human lympho id system using mAb, but only a few such markers are detectable in ani mal species. In this paper, we have investigated the interspecies reac tivity of antibodies raised against intracytoplasmic peptide sequences from two T cell Ag (CD3 and CD5) and two B cell markers (the Ig-assoc iated polypeptides encoded by the mb-1 and B29 genes). Immunocytochemi cal labeling of tissue sections showed that these antibodies cross-rea ct widely between different species (including ungulates, rodents, and marsupials), staining B or T cell areas selectively in lymphoid tissu e. The specificity of these antibodies for the animal homologues of th e human T and B cell markers was confirmed for the rat by Western blot ting analysis. The broad cross-reactivity of these antibodies appears to be due to the fact that they were raised against intra-cytoplasmic peptide sequences that are highly conserved between humans and rodents , i.e., 80% for mb-1, 85% for CD5, and 100% for CD3 and B29. This stra tegy should, in the future, widen the range of lineage-associated mark ers detectable in experimental animals.