Phenotypic analysis of IL-10-treated macrophages using the monoclonal antibodies RFD1 and RFD7

Suppressive or tolerogenic antigen-presenting cells (APC) might play an imp ortant role in the control of auto/hyperreactivity and the resolution of th e immune response. Recent studies have provided evidence that tolerogenic A PC can be induced by anergic T cells or interleukin-10 (IL-10). The aim of this study is to investigate how anergic T cells and IL-10 induce the suppr essive APC phenotype and how this affects the immune response. Previously, two monoclonal antibodies (RFD1 and RFD7) were described by our lab which d istinguish inductive (RFD1+RFD7-), phagocytic (RFD1-RFD7+) and suppressive (RFD1+RFD7+) macrophages. RFD1 recognizes an MHC class Ii-associated epitop e which has restricted expression, and RFD7 recognizes a predominantly cyto plasmic antigen. Macrophages were derived from the adherent fraction of per ipheral blood mononuclear cells from healthy donors. At day 5, IL-10 or IFN gamma (a cytokine which should lead to the inductive APC phenotype) was ad ded to the cultures. At day 7, the macrophages were harvested and their phe notypes were assessed by immunohistochemical staining and FAGS analysis. Up on culture of macrophages with IL-10 RFD1 staining and HLA class II express ion were reduced, whereas RFD7 staining was increased. Incubation of APC wi th IFN gamma led to upregulation of RFD1 and HLA class II, without affectin g RFD7 staining. This suggests that IL-10 induced the suppressive RFD1+RFD7 + APC population, whereas IFN gamma treatment led to the inductive RFD1+RFD 7- APC subset. Thus the use of IL-10 and/or IFN gamma, and the discriminati on offered by mAbs RFD7 and RFD1 represent a model whereby APC function in terms of T cell stimulation or T cell anergy can be assessed. Copyright (C) 2000 S. Karger AG. Basel.