Toward harmonized phenotyping of human myeloidder

Authors: Susanna Mandruzzato Sven Brandau Cedrik M Britten Vincenzo Bronte Vera Damuzzo Cécile Gouttefangeas Dominik Maurer Christian Ottensmeier Sjoerd H van der Burg Marij J P Welters Steffen Walter

Publish Date: 2016/01/04

Volume: 65, Issue: 2, Pages: 161-169

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Abstract

There is an increasing interest for monitoring circulating myeloidderived suppressor cells MDSCs in cancer patients but there are also divergences in their phenotypic definition To overcome this obstacle the Cancer Immunoguiding Program under the umbrella of the Association of Cancer Immunotherapy is coordinating a proficiency panel program that aims at harmonizing MDSC phenotyping After a consultation period a twostage approach was designed to harmonize MDSC phenotype In the first step an international consortium of 23 laboratories immunophenotyped 10 putative MDSC subsets on pretested peripheral blood mononuclear cells of healthy donors to assess the level of concordance and define robust marker combinations for the identification of circulating MDSCs At this stage no mandatory requirements to standardize reagents or protocols were introduced Data analysis revealed a small intralaboratory but very high interlaboratory variance for all MDSC subsets especially for the granulocytic subsets In particular the use of a deadcell marker altered significantly the reported percentage of granulocytic MDSCs confirming that these cells are especially sensitive to cryopreservation and/or thawing Importantly the gating strategy was heterogeneous and associated with high intercenter variance Overall our results document the high variability in MDSC phenotyping in the multicenter setting if no harmonization/standardization measures are applied Although the observed variability depended on a number of identified parameters the main parameter associated with variation was the gating strategy Based on these findings we propose further efforts to harmonize marker combinations and gating parameters to identify strategies for a robust enumeration of MDSC subsets

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