Immune system cell markers in the northern brown bandicoot, Isoodon macrourus

This is the first study to report the presence of T and B lymphocyte marker s and antigen presenting-like molecules in a marsupial bandicoot. Intra-cyt oplasmic markers for CD3 and CD5, as well as surface Thy-1.1 and CD1a molec ules were located in lymphocytes of T dependent regions of immuno-lymphoid tissue in the northern brown bandicoot using immunohistochemical techniques . Similarly, intra-cytoplasmic domains of CD79a, CD'79b molecules and surfa ces IgG molecules enabled characterisation of B lymphocytes and plasma cell s. The phenotypic expression of these molecules parallels findings in euthe rians, suggesting firstly the conservation of lineage epitopes for T and B subsets and secondly, the potential for similar functional properties of im mune system cells between marsupials and eutherians. In addition, the prese nce of MWC class II and CD1a molecules on dendritic-like cells may indicate similar mechanisms for antigen processing and presentation as reported in eutherians. The use of such immune system cell markers will enable function al studies to characterise the marsupial immune system as well as ontogeny studies of immune competence. (C) 2000 Elsevier Science Ltd. All rights res erved.