OR40 Applying single-cell mass cytometry to investigate the immune system of highly sensitized patients who undergo intravenous immunoglobulin desensitization treatment

Abstract

Aim To identify potential immune markers for predicting and monitoring IVIG desensitization by CyTOF technology. Methods CyTOF: A panel of 37 antibodies against phenotypic and functional immune makers were labelled with metals and used to define 27 cell populations by Single-cell mass cytometry. Applying Cytobank ( http://www.cytobank.org ) (Chen and Kotecha, 2014), visualizing cellular features of interest across all the cells in a dataset were manually gated and clustered cell population according to the proper cell markers. SEM (Significance Analysis of Microarrays) paired algorithms was used for the data statistical analysis. Results Two highly sensitized patient frozen PBMC samples were tested in vitro and in vivo by CyTOF. The expression of HLA-class I (HLA-I) decreased in all cell populations after incubating patient PMBC (in vitro sample) with 2.5%IVIG for 16 h. Excepting B cells, the expression of HLA-I also decreased after 15 courses of IVIG treatment (in vivo sample). IVIG treatment increased inhibitory Fc receptor CD32IIb expression significantly on basophils, myeloid dendritic cells (DC), and all B cells (especially memory B cells) in vivo; and increased CD56 and CD25 expressions on NK cells and Treg cells respectively. Conclusions IVIG treatment significantly increases inhibitory markers expression on APC cells and activated Treg cells in desensitization patient. Inhibitory Fc receptor CD32IIb, CD56, CD25, and HLA-I could be useful immune marker for predicting and monitoring IVIG efficacy in desensitization.