Immunofluorescence analysis of immunoglobulin bearing lymphocytes in the Indian fruit bat: Pteropus giganteus.

The immunologic cell types of the Indian fruit bat, P. giganteus, were characterized on the basis of cell surface Ig markers. Rabbit anti-rat IgM and IgG demonstrated IgM or IgG bearing cells in the nylon wool adherent lymphocyte population, thereby suggesting their equivalence to the B cells of recently evolved mammals including man. Relative proportion of these Ig+ surface bearing cells was about one-half of the bone marrow lymphocytes, one-third of mesenteric lymph node lymphocytes, and two-thirds of the splenic and peripheral blood lymphocytes. Considering the early origin of Megachiropters (fruit bats) in mammalian evolution, it is suggested that surface characteristics of typical mammalian lymphocytes like Ig markers as such or as genomic messages existed at the time of evolution of Class Mammalia. The high percentage of surface Ig+ cells in the peripheral circulation of bats suggests a "natural immunodeficiency state", which may be equivalent to immunodeficiency state in humans.