Severe B cell depletion in newborns from renal transplant mothers taking immunosuppressive agents

There have been several reports of successful pregnancies of kidney transplant mothers receiving immunosuppressive agents such as CsA and/or AZA. However, few papers have investigated immune function of neonates from those mothers. We investigated the lymphocyte subpopulations and T cell subsets in cord blood of newborn infants from those mothers. The subjects were 6 infants born to mothers following renal transplantation, who all were receiving CsA, AZA, and methylprednisolone. Cord blood and peripheral blood at 1 month and 3 months of age were obtained from the subjects. Control samples were obtained from 5 normal newborns. The polyclonal antibody used to investigate B cells was anti-F(ab')2 fragment of human immunoglobulin. Direct immunofluorescence staining and flow cytometry were used for the investigation. The number of B cells and the percentage of B cell in total mononuclear cells were significantly lower in the subjects than in normal controls. There was no significant difference between numbers of CD2+, CD4+, or CD8+ cells in the subjects and the controls. This severe B cell depletion remained low at 1 month and 3 months of life in many cases. From our result, it is very possible that the B cell line is more sensitive to immunosuppressants in utero than the T cell line. Infants of mothers taking immunosuppressive agents during their pregnancy should be followed carefully for possible insufficiency of immune function.