IMMUNOSUPPRESSIVE EFFECT OF A LOW-MOLECULAR-WEIGHT SURFACE PROTEIN FROM RENIBACTERIUM-SALMONINARUM ON LYMPHOCYTES FROM ATLANTIC SALMON (SALMO-SALAR L)

The immunosuppressive effect of Renibacterium salmoninarum surface pro teins, p22 and p57, on lymphocytes was studied. It has been shown earl ier that the p57 protein suppresses the antibody production by salmoni d B cells. In this study, the suppressive effect of a surface protein with a molecular weight of 22 kDa was compared with that of p57. The p 22 and p57 proteins were isolated by gel filtration. The purity of the proteins was assessed by SDS-PAGE and Western blotting using a monocl onal antibody to p57 and a mouse antiserum to p22. Both p22 and p57 we re found to suppress the specific antibody production by salmonid B ce lls in vitro, as measured by ELISPOT. The proteins also agglutinated s almon leucocytes. (C) 1997 Academic Press Limited.