Detection of microchimeric cells in the peripheral blood of nonpregnant women is enhanced by magnetic cell sorting before PCR.

Abstract

Our laboratory and others have demonstrated the presence of microchimeric cells in the peripheral blood of nonpregnant patients with systemic sclerosis (SSc) (1)(2)(3)(4). In addition, we have demonstrated the presence of maternal microchimeric cells in the peripheral blood of patients with juvenile idiopathic inflammatory myopathies (5), an observation confirmed in a subsequent study (6). However, some recent reports describe the failure to demonstrate the presence of male microchimeric cells in the peripheral blood of women with SSc or myopathies (7)(8)(9)(10). These latter studies used PCR amplification (9) or nested PCR (7)(8)(10) of Y-chromosome DNA sequences in whole peripheral blood. Various PCR methods have been used for detection of microchimeric cell DNA in peripheral blood. These methods have been applied primarily to studies of organ transplantation or prenatal diagnosis (11)(12)(13)(14). However, the reliable detection and quantification of minute amounts of microchimeric DNA within a large pool of recipient DNA has been problematic. The need to limit the amount of autologous DNA in PCR analyses is likely to be an important determinant of the lower limit of detection for minor nonautologous cell populations. Numerous methods have been used for the detection of fetal cells for prenatal diagnosis in the peripheral blood of pregnant women; however, magnetic cell sorting is the most commonly used (15). Magnetic cell sorting for fetal erythroblasts has been used extensively in the analysis of peripheral blood of pregnant women (16)(17)(18), and this approach (18)(19) enriched the fetal cells ∼200-fold (17). We examined whether magnetic cell sorting to isolate specific cell types used successfully in the detection of microchimeric fetal cells in pregnant women (18)(19) would improve the …