Surface immunoglobulins on the lymphocytes of the skate Raja naevus

Living lymphocytes of the Elasmobranch fish, Raja naevus, have been examined for surface immunoglobulin (Ig) by treatment with a fluorescent anti-Ig system. Large numbers of Ig-positive cells (60-80%) were found in peripheral blood, spleen and thymus. Following modulation of the surface Ig with anti-Ig, resynthesis occurred, showing that the surface Ig is a product of the individual lymphocytes rather than material passively absorbed from the serum. Formation of caps was independent of temperature, occurring as readily at 4 degrees C as at 20 degrees C, a finding which presumably reflects the environmental conditions normally experienced by the skate. The presence of Ig-bearing lymphocytes in the adult skate thymus suggests a similarity to the amphibian larval thymus, which may be a primary lymphoid organ for the production of both T and B lymphocyte analogues.