Adoptive transfer of gut mucosal antitoxin memory by isolated B cells 1 year after oral immunization with cholera toxin.

A protocol was elaborated for the adoptive transfer of lymphocytes from mice which were orally immunized with cholera toxin (CT) to enable the study of long-term gut mucosal immunological memory at the single-cell level. Mesenteric lymph node (MLN) cells were transferred 1 year after priming immunizations, and recipient animals were challenged perorally on days 1 and 2 with CT before sacrifice on day 6 to 7 following transfer of cells. Strong antitoxin ELISPOT spot-forming cell (SFC) responses were recorded in spleens, MLN, and laminae propriae (LP) of recipient mice. In contrast, no SFC were found in Peyer's patches. The magnitude of the response equaled that of the acute response seen after optimal oral CT immunization and was directly dependent on the number of transferred cells. The memory antitoxin response in MLN and LP required oral challenge with CT as opposed to the spleen SFC response, which could also be triggered by intravenous challenge with antigen. Spleen cells from mice immunized perorally with CT were as effective as MLN cells in transferring immunological memory detectable in the gut immune system. Irrespective of the tissue source of transferring immunological memory detectable in the gut immune system. Irrespective of the tissue source of the memory cells, the isotype distribution of the antitoxin SFC response in recipient mice was similar with predominantly immunoglobulin A (96%) in LP and immunoglobulin G (66%) in MLN and spleen. Transfer of antitoxic memory was completely abrogated by treatment of the cells with J11d monoclonal antibody and complement prior to their injection into recipient mice by was unaffected by treatment with anti-Thy-1.2 antibody and complement, suggesting that long-term gut mucosal memory is carried by B cells. Antitoxin B memory cells might help explain the long-term protection against recurrent disease seen in convalescents from cholera in cholera-endemic areas.