Description:
AbstractPublic and private idiotopes (Id) had been defined in the BALB/c anti‐dextran B1355 fraction S (Dex) response by means of syngeneic monoclonal anti‐M 104E Id antibodies. Most of the primary anti‐Dex antibodies shared the public Id‐1 while the private Id‐5 constituted a comparatively low, but highly variable proportion of humoral anti‐Dex antibodies of individual mice. In the present work we have analyzed by limiting dilution the expression of these two Id by anti‐Dex B cell precursors from the spleen and peritoneal cavity of BALB/c mice. Testing spleen cells we found about 65% of anti‐Dex precursors to be Id‐1+ and only a minority to be Id‐5+. Treatment with anti‐Ly‐1 and complement was without any effect on anti‐Dex precursors from spleen. Anti‐Dex B cell precursors among peritoneal cavity lymphocytes differed from those found in the spleen in two ways. First, on average, 50% of them were Id‐5+; second, about 80% carried the Ly‐1 marker. Both markers are, therefore, expressed on at least 30% of anti‐Dex B cell precursors from the peritoneal cavity but rarely on anti‐Dex precursors from the spleen.