Immunohistological staining of lymphoid tissue in four Australian marsupial species using species cross-reactive antibodies.

Antibodies raised against evolutionarily conserved intracytoplasmic peptide sequences of human T and B lymphocyte antigens and an antibody raised specifically against koala serum IgG were assessed for their capacity for immunoperoxidase staining of formalin fixed lymphoid tissues of koalas (Phascolarctos cinereus), common brushtail possums (Trichosurus vulpecula), common ringtail possums (Pseudocheirus peregrinus) and tammar wallabies (Macropus eugenii). Utilizing microwave pretreatment and a streptavidin biotin-horseradish peroxidase method for histochemical staining, polyclonal anti-human CD3 (for T cells), monoclonal anti-human CD5 (for T cells), monoclonal anti-human CD79b cy (for B cells) and polyclonal anti-koala IgG (for plasma cells) consistently stained lymphoid elements in a wide range of tissues from all four marsupial species. Monoclonal anti-human CD79a cy (for B cells) stained lymphoid elements in only brushtail possums. This is the first report of immunohistological staining of lymphocytes in Australian marsupials, thereby vastly increasing the scope for immunological studies in these species.