Background The influence of inflammatory processes has been one of the hot topics in discussions of the etiology of chronic venous insufficiency(CVI).Erythrocytes are very important in controlling inflammatory immunity and innate immune reactions.The purpose of this study was to analyze the correlation between the development of CVI and the change of CD35,Fy6 on erythrocytes,and interleukin-8(IL-8) levels.Methods A group of 43 patients with CVI were studied in parallel with 8 healthy individuals serving as centrol subjects.Control subjects were those with normal findings on lower extremity duplex examinations.We used an erythrocyte flow cytometer to examine the expression of both CD35 and Fy6 on red blood cells,and an enzyme-linked immunosorbent assay analysis method to measure plasma IL-8 levels.We also analyzed the change of IL-8 levels under the influence of erythrocytes using a modified method of the hemaimmune reaction.Results Compared with normal centrol subjects,CD35 expression increased significantly among patients with CVI classified as C4 without lipodermatosclerosis,but tended to decrease and reach the lowest level among patients classified as C5-C6.Fy6 expression increased significantly among patients in the early stages of CVI,but tended to decrease remarkably among patients classified as C5-C6.The inflammatory response intensified at the C5-C6 classification,where high levels of IL-8 coexisted with a low expression of Fy6.The increase in IL-8 in the CVI group was higher than in the control group in association with the complete blood cells,regardless of the presence of erythrocytes,when inactive tumour cells were added,whereas the level of IL-8 in the CVI group was significantly lower than in the control group.Conclusions Abnormalities of erythrocyte innate immunity represents a fundamental derangement in CVI.These inadequate inflammatory responses may lead to local tissue and microvascular damage of the lower extremity.