Natural killer (NK) cell subsets and NK cell cytotoxicity in women with histories of recurrent spontaneous abortions

PROBLEM: Natural Killer (NK) cell measurement and NK cytotoxicity are two m easurements for assessing the cellular immune response. Both of the techniq ues have been reported to be prognostic for women with recurrent spontaneou s abortion (RSA). We evaluated the two methods to determine the relationshi p of the two assays. Because both methods portend to evaluate the same proc ess, the previous clinical data suggested that the methods evaluate the sam e phenomena. We undertook these studies to determine whether simple NK cell counts may be sufficient in the evaluation of NK activity in RSA. METHOD OF STUDY: The NK cell cytotoxicity at effector-to-target ratios of 5 0:1 and 25:1 was determined using a flow cytometric NK cell cytotoxicity as say. These values were then correlated with the percentages and absolute co unts of three peripheral blood NK cell subsets. RESULTS: The data indicate that the flow cytometric assay is reproducible a nd precise and can be successfully used to evaluate patient samples. Linear regression analysis indicated a lack of correlation between peripheral blo od NK cell cytotoxicity and percentages or absolute counts of CD56 + CD16 , CD56 + CD16 - or CD3 + CD56 + lymphocyte subsets (range of correlation co efficients, 0.1-0.3). CONCLUSIONS: NK cell cytotoxicity and peripheral blood NK cell values measu re different aspects of NK cells and do not correlate. These data indicate that simple enumeration of NK cells may not be sufficient in the evaluation of NK cells in RSA.