City of Hope Duarte

Angels Camp, CA, United States

City of Hope Duarte

Angels Camp, CA, United States

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Cao L.-F.,Clinical Immunobiology Correlative Studies Laboratory | Krymskaya L.,Clinical Immunobiology Correlative Studies Laboratory | Tran V.,Clinical Immunobiology Correlative Studies Laboratory | Mi S.,Clinical Immunobiology Correlative Studies Laboratory | And 3 more authors.
Cytometry Part A | Year: 2010

Although target cell cytolysis has been widely employed to describe effector function of cells, cytolysis assays as commonly employed do not generate quantitative data. In this report we describe the development and application of a statistically supported flow cytometry-based assay to quantify cell-mediated cytolysis. The assay depends on the use of the fluorescent dye CFSE to distinguish target from effector cells, the DNA intercalating dye 7AAD to distinguish dead from live cell events, and on the establishment of a cytolysis curve that allows for the derivation of statistically robust data. We demonstrate that the cytolysis curve is well described by a four parameter logistic regression model provided that (i) the range of effector to target (E:T) ratios studied allows for full description of the logistic curve, and (ii) an adequate number of data points are collected to estimate the model parameters. We show that the assay is highly reproducible and accurate, and comparable in sensitivity with the standard 51Cr assay. We report on the potential for this assay to generate quantitative data on the cytolytic activity of both CD8 T and NK cells; describe a relationship between the efficiency of effector cell degranulation and target cell cytolysis throughout a range of E:T ratios, and demonstrate the potential to multiplex with other platforms to obtain broader datasets for the effector phenotype of cells. Appropriate use of this assay will enhance the ability to derive quantitative and integrated correlative datasets from basic, translational, and clinical studies. © 2010 International Society for Advancement of Cytometry.


Natural killer (NK) cells whose killer immunoglobulin-like receptors (KIRs) recognize human leukocyte antigen (HLA) ligand are licensed for activity. In contrast, non-licensed NK cells display KIRs for which ligand is absent from the self genotype and are usually hyporesponsive. Surprisingly, non-licensed cells are active in tumor control after hematopoietic stem-cell transplantation (HSCT) and dominate NK response to murine cytomegalovirus (CMV) infection. From those reports, we hypothesized that control of human CMV early after HSCT is influenced by donor KIR genes whose HLA ligand is absent-from-genotype of HLA-matched donor and recipient. To investigate, we studied CMV reactivation through Day 100 after grafts involving CMV-seropositive donor and/or recipient. A multivariate proportional rates model controlled for variability in surveillance and established covariates including acute graft-versus-host disease; statistical significance was adjusted for testing of multiple KIRs with identified HLA class I ligand (2DL1, 2DL2/3, 2DS1, 2DS2, full-length 2DS4, 3DL1/3DS1, 3DL2). Among HSCT recipients (n = 286), CMV reactivation-free survival time varied with individual donor KIR genes evolutionarily specific for HLA-C: when ligand was absent from the donor/recipient genotype, inhibitory KIRs 2DL2 (P < 0.0001) and 2DL1 (P = 0.015) each predicted inferior outcome, and activating KIRs 2DS2 (P < 0.0001), 2DS1 (P = 0.016), and 2DS4 (P = 0.016) each predicted superior outcome. Otherwise, with ligand present-in-genotype, donor KIR genes had no effect. In conclusion, early after HLA-matched HSCT, individual inhibitory and activating KIR genes have qualitatively different effects on risk of CMV reactivation; unexpectedly, absence of HLA-C ligand from the donor/recipient genotype constitutes an essential cofactor in these associations. Being KIR- and HLA-C-specific, these findings are independent of licensing via alternate NK cell receptors (NKG2A, NKG2C) that recognize HLA-E.

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