CELLULAR BASIS FOR DIFFERENCES IN HUMORAL IMMUNE RESPONSES OF SHEEP IMMUNIZED WITH LIVING OR KILLED STAPHYLOCOCCUS AUREUS VACCINES

Summary An immunohistological study was made of immunoglobulin‐containing cells and antibody‐containing cells in abscesses/granulomas which formed al the injection site, draining popliteal nodes and contralateral popliteal nodes of sheep given either a living Staphylococcus aureus vaccine (Group L), a killed S. aureus vaccine with Frennd's complete adjuvant (FCA) (Group K) or FCA alone (Group C). The injections were made subcutaneously in the hind legs and second injections were gives 4 weeks later in the same site. Very large numbers of IgM‐containing cells were found in granulomas of Groups K and C at 1 week post‐injection (PI) but by 2 weeks PI only small numbers were recorded. Following booster immunization, the numbers of IgM‐containing cells were greater in abscesses from sheep in Group L than from granulomas from sheep in Group K. Levels for Group C remained low after 1 week PI. There was evidence that the very early IgM‐containing cell response in Group K was largely unrelated to specific anti‐staphylococcal antibody synthesis. The IgG 2 ‐containing cell response was significantly greater than the IgG 1 ‐containing cell response in abscesses and nodes in Group L. In contrast, for animals in Groups K and C the IgG 1 ‐containing cell response predominated over the IgG 2 ‐containing cell response in granulomas and draining nodes. There were generally greater numbers of cells containing anti‐staphylococcal antibody in abscesses granulomas and nodes in Group L than in Group K.