BACKGROUNDCD200 and its receptor CD200R are both type-1 membrane glycoproteins, which are members of the immunoglobulin superfamily (IgSF). Besides the inhibitory effect on macrophages, CD200/CD200R also play an important role in regulating the regulatory T cells, allergicreaction, autoimmune diseases, allograft, neurological diseases and other autoimmune-related diseases, etc.

OBJECTIVETo investigate the role of CD200 and its receptor in the graft versus host disease (GVHD).

METHODSExperimental samples were divided into aGVHD group, non-aGVHD group, cGVHD group and non-cGVHD group, the healthy persons were used as normal controls. Firstly, the expression levels of CD200 and CD200R on CD19+ cell, CD3+ cell and dendritic cell (CD19- CD14- CD1c+) surfaces in each group were detected by using flow cytometry, so as to determine whether there were expression differences among each groups. Then, the mRNA levels of each groups were tested by using real-time quantitative polymerase chain reaction for finding the differences of mRNA expression level among each group. Finally, the peripheral blood mononuclear cells of the patients and healthy controls were co-cultured with anti-CD200R1 antibody for 48 hours, and the interleukin-10 level in the co-culture system was tested by using enzyme linked immunosorbent assay for verifying the function of CD200/CD200R.

RESULTSThe CD200 expression level on CD19+ cell surface in the aGVHD group and non-aGVHD group was both lower than that in healthy control group; that in the non-aGVHD group was higher than that in the aGVHD group. The CD200 expression level on CD19+ CD200+ cells in the non-cGVHD group were higher than that in the cGVHD group and healthy control group. There were no significant differences of CD200 and CD200R expression levels on CD3 cells and dendritic cells among all groups. The CD200 mRNA expression levels in the aGVHD group and cGVHD group were both lower than the healthy control group. The CD200 mRNA expression level was lower in the aGVHD group than in the non-aGVHD group, and was lower in the cGVHD group than in the non-cGVHD group. There was no significant difference of the CD200R mRNA expression level among all groups. After the peripheral blood mononuclear cells of the patients and healthy controls were co-cultured with anti-CD200R1 antibody for 48 hours, the interleukin-10 concentration decreased with the increasing of anti-CD200R1 antibody concentrations in the co-culture system.

CONCLUSIONThe CD200/CD200R may play a role in the pathogenesis of GVHD after allo-HSCT.