Cell numbers in synovium-rich tissue (SRT) of hind paws during the course of adoptively transferred arthritis. Dual-color flow cytometry was used to analyse cell surface antigens, and CaliBRITE beads were used to estimate cell numbers per pair of hind paws (mean ± standard deviation, n = 5). (a) Numbers of total CD45+, CD45+MHC IIhi, CD45+MHC IIlo, and CD45+MHC II- cells in SRT prepared from normal rats and from rats 3 to 14 days after adoptive transfer of arthritis. (b) Numbers of MHC IIhi and MHC IIlo/- macrophages (CD45+CD163+ cells) in SRT after adoptive transfer of arthritis. Cell surface antigen phenotype of CD45+MHC IIhi cells in SRT after adoptive transfer of arthritis, expressed as proportion of cells positive for each marker (c) and numbers of cells expressing the markers (d). MHC, major histocompatibility complex.