Enumeration of lymphocyte populations in whole peripheral blood of patients with antibody-mediated nephritis during treatment with cyclosporin A.

Lymphocyte populations identified by surface markers were enumerated in whole peripheral blood of 3 patients with Goodpasture's syndrome (mediated by anti-glomerular basement membrane antibody) whilst on treatment with cyclosporin A (CSA). The whole blood method, using alkaline phosphatase-labelled reagents, permits precise enumeration of the relative and absolute numbers of lymphocyte subsets in the circulation. Using conventional rabbit and monoclonal mouse anti-human T-cell antibodies, a small decrease in the percentage of T-lymphocytes was noted following the start of CSA treatment. The absolute T-cell count fell, but only to just below normal. There was no marked or consistent effect on the percentages or absolute numbers of B-cells, C3b-receptor or Fc(gamma)-receptor bearing lymphocytes. These results are compatible with a mechanism of immunosuppression by CSA in which there is selective inhibition of a relatively minor subset of T-lymphocytes.