Cellular distribution of protein-disulfide interchange enzyme activity in mouse spleen

In an attempt to precise the cellular distribution of protein-disulfide interchange enzyme activity within different compartments of the splenic lymphoid tissue, we have analyzed the protein-disulfide interchange (PDI) enzyme activity in adherent and nonadherent cell populations of normal and T-cell depleted CBA mice. In vivo depletion of T-cells, as evaluated by functional and cytotoxic tests, was achieved by two i. v. injections of anti-T monoclonal antibodies (Mab F7D5). Nonadherent cell populations were found to have levels of protein-disulfide interchange enzyme activity significantly higher than that of the adherent cells. Pretreatment with F7D5 monoclonal antibodies enhanced the protein-disulfide interchange activity in nonadherent cell population, thus indicating that the major source of the enzyme activity are nonadherent spleen cells, which do not bear T-cell marker, probably B-cells.