106 SUBPOPULATIONS Vol. IO, No. 1

GUT ASSOCIATED LYMPHOID TISSUE IN THE DOGFISH (SCYLIORHINUS CANICULA L.)

S. Hart and J.E. Harris. Plymouth Polytechnic, Plymouth, Devon, England.

Preliminary light microscropic studies have revealed extensive populations

of leucocytes in the alimentary canal of the dogfish (Scyliorhinus canicula L)

These have been recognised principally in the pyloric stomach and spiral

valve, to a lesser extent in the oesophagus and rectum, and absent from the cardiac stomach. Lymphocytes, macrophages and a variety of granulocytes

have been identified both by light and electron microscopy, and their

distribution recorded. The cells were present in the lamina propria and

epithelium of the gut. Najor accumulations of lymphocytes and macrophages

occurred in the pyloric stomach and spiral valve. ~he role of these cells

in the immunological function of the gut is discussed.

CELLULAR REQUIREMENTS FOR IN VITRO IMMUNE RESPONSES WITH CHANNEL CATFISH LEUKOCYTES. N.W. Miller, R°C. Sizemore, A. Deuter, and L.W. Clem. University of Mississippi Medical Center, Jackson, Mississippi, USA.

Three functionally distinct leukocyte subpopulations were isolated from the peripheral blood of channel catfish. Surface immunoglobulin positive (slg) and slg- lymphocytes were isolated by an indirect "panning" procedure employing monoclonal antibodies specific for channel catfish Ig. A third population composed of macrophages was isolated by adherence to baby hamster kidney cell microexudate coated surfaces. Functional features of these three cell types were established by assessing their role(s) in I) primary in vitro anti-hapten PFC responses to murine thymus-dependent (TD) and thymus-independent (TI) antigens and 2) one-way mixed leukocyte reactions (MLR). The results indicated tha+t anti-hapten PFC responses to a TI antigen required the presence of slg lymphocytes and macrophages. In contrast, all three cell types were required for responses to TD antigens. Furthermore, the results of studies involving the depletion of a~tigen-reactive lymphocytes demonstrated that both hapten-specific slg cells and carrier-specific slg- cells were required for anti-hapten responses to TD antigens. The results of studies on the MLR indicated that the slg- lymphocytes contained the responding population whereas the macrophages (and to a lesser extent the slg lymphocytes) were the stimulating cells. These studies document that channel catfish possess the functional equivalents of B cells, T cells and accessory cells.