Four-color flow cytometry of subsets from synovium-rich tissue (SRT) following adoptive transfer of arthritis. Cell numbers per pair of hind paws (mean, n = 2) were estimated by use of CaliBRITE beads. (a) Numbers of putative dendritic cells (MHC IIhiCD163- cells) with CD4+CD11b+ or CD4-CD11b+ phenotype. (b) Proportions of the same subpopulations. Numbers of CD4- and CD4+ macrophages in the MHC IIhi (c) and MHC IIlo/- (d) subpopulations of CD45+CD163+ cells. (e) Numbers of MHC II-CD45+ cells in SRT after adoptive transfer of arthritis. MHC II- cells with the phenotype CD11b+CD4-CD163- were defined as polymorphonuclear (PMN) cells, whereas those with the phenotypes CD11b+CD4-CD163lo and CD11b+CD4+CD163lo were designated as monocytes. MHC, major histocompatibility complex.