Two populations of immunoglobulin-forming cells in the skate, Raja kenojei: their distribution and characterization.
We recently reported the presence in the skate, Raja kenojei, of two immunoglobulins, a high molecular weight immunoglobulin analogous to mammalian IgM, and a low molecular weight immunoglobulin belonging to a hitherto undescribed class. In view of these findings, we studied lymphoid organs of the skate using morphological and immunocytochemical means. The spleen and the intestinal mucosa had numerous plasma cells and lymphocytes, while the Leydig organ of the esophagus, the epigonal organ and the liver contained these cells in a much lesser frequency. Immunocytochemical studies proved these plasma cells and some of the lymphocytes to be immunoglobulin-forming cells. Double immunofluorescence staining of the spleen and other lymphoid tissues demonstrated the occurrence at a 1: 1 ratio of two distinct populations of cells, one forming the high molecular weight immunoglobulin and the other producing the low molecular weight immunoglobulin.