Background: Renal transplantation across the blood barrier is a unique model for investigating the humoral response to different carbohydrate antigens. However, in such a renal transplantation, the characteristics of B cells as well as of the antibodies produced by B cells are less well defined.
Methods: In the present study we investigated B cell subsets (i.e., the CD5(+) B-1 and CD5- B-2 subsets) by flow cytometric analysis, and their subclasses of antibody, by ELISA, in patients who had undergone renal transplantation across the blood barrier. The subjects consisted of five recipients with good function (group 1) and five recipients with graft loss (group 2) accompanied by antibody-titer elevation after ABO-incompatible renal transplantation.
Results: The B-cell population analysis revealed that CD5(+) B-1 cells temporarily increased in all patients in both groups soon after transplantation, and that CD5- B-2 cells significantly increased 1 month after transplantation only in group 2. The antibody subclasses analysis showed mild elevation of immunoglobulin (Ig) G2 and IgM in group 1 as opposed to remarked elevation of IgG2, IgM and IgG1 in group 2.
Conclusions: The results of this study suggested that CD5(+) B-1 cell T-independent activation usually occurs soon after ABO-incompatible renal transplantation, but that CD5- B-2 cell T-dependent activation occurs only in patients who experience graft rejection.