SYNTHESIS OF IMMUNOGLOBULINS BY LYMPHOID-CELLS IN SHEEP - CONTRIBUTION MADE BY LYMPHOBLASTS TO TOTAL IMMUNOGLOBULIN AND ANTIBODY-PRODUCTION BY LYMPHOID-CELLS OF POPLITEAL NODE DURING A SECONDARY RESPONSE TO BACTERIAL LIPOPOLYSACCHARIDE

The production of immunoglobulin (Ig) and antibody by lymphoid cells of sheep popliteal lymph node was studied in vivo and in vitro during a secondary response to lipopolysaccharide extracted from Salmonella muenchen. The maximum production of Ig in vitro occurred on the 4th and 5th days of the response and the proportion of the Ig expressing affinity for the antigen was also maximal at this time. By infusing [3H]leucine into the node via a chronic fistula, it was possible to assess the relative contributions made by the blast cells to the total Ig production by the node at various times in the response. There were 3 phases of Ig production. The blast cell may be the primary antibody-producing cell involved in providing protection to the animal against the initial antigenic assault. The role of the plasma cell would be one of maintaining levels of specific antibody in the blood and extravascular spaces for a period of time after the main antigenic challenge has passed. Alternatively, the plasma cell may simply be an end cell.