A NOVEL BOLA CLASS-II MOLECULE WITH A TISSUE DISTRIBUTION DIFFERENT FROM BOLA-DR OR BOLA-DQ MOLECULES

This study was designed to investigate the lymphoid tissue distributio n of a new BoLA class II molecule defined by a unique monoclonal antib ody H42A. We immunostained various lymphoid organs of 4-month-old Hols tein calves with this monoclonal antibody and compared its tissue dist ribution to the BoLA-DR and BoLA-DQ expressions. Our results demonstra te a unique tissue distribution of the HC2A-defined molecules, restric ted to epithelial cells of the thymic medulla but extending in the per iphery to the different cells involved in antigen presentation (B-cell s, macrophages and dendritic cells). The peculiar distribution of this new BoLA class Il molecule suggests that it has a specific function.