Abstract: Objective: To determine the regulatory effect of histamine 4 receptor (H4R) on dendritic cells (DC) in children with Henoch-Sch?nlein purpura (HSP). Methods: The expression levels of CD80 and CD86 in PBMC from 126 patients at acute stage, 112 at remission stage and 94 healthy controls were detected by flow cytometer. The DC was isolated and divided into the histamine group, histamine+H4R antagonist group and PBS control group. The levels of H4R and P-STAT1 proteins on DC were detected by Western blot and the levels of CCL17and CXCL16 were detected by ELISA. Results: The level of CD86 from the patients with HSP was higher than that in healthy controls, with a significant difference (P<0.01), while the level of CD80 was lower in the patients at acute stage than that in the patients at remission stage and healthy controls (P<0.01). The difference in the level of CD 80 between the patients at remission stage and healthy controls was not significant. The level of H4R and P-STAT1 proteins, CXCL16 and CCL17 on DC in the histamine+H4R antagonist group were lower than those in histamine group. Conclusion: H4R is associated with the onset and development of HSP, which may go through up-regulating the levels of CXCL16 and CCL17 and activating the JAK/STAT pathway.

Key words: Henoch-Sch?nlein purpura, dendritic cell