The deviations of CD4 + T cells during peripheral blood and peritoneal fluid of endometriosis: a systematic review and meta-analysis

Objective: To assess whether endometriosis (EMs) was related to systematic and/or local deviations of cluster of differentiation (CD)4 + T cells. Methods: Until November 2022, we enrolled a total of 1363 EMs and 1564 healthy women from 32 studies who met the inclusion criteria. Results: After systematically retrieving the literature, we identified 1086 citations and 32 case–control studies were enrolled. Cumulative results suggested that there were insignificant deviations of CD4 + T cells during peripheral blood (PB) between EMs and healthy women (RR: − 0.83, I = 99%, p = 0.65), also no statistically significant difference was found between mild and severe EMs (RR: 3.19, I = 94%, p = 0.19). We also found insignificant deviations of CD4 + /CD8 + during PB between EMs and healthy women (RR: 0.09, I = 99%, p = 0.39), and between mild and severe EMs (RR: − 0.16, I = 99%, p = 0.29). The results might suggest that there was no significant correlation between EMs and systematic deviations of CD4 + T cells. When it came to local deviation during peritoneal fluid (PF), the polled results suggested that the frequency of CD4 + T cells during EMs was significantly lower than healthy women (RR: − 5.38, I = 93%, p = 0.01), and the ratio of CD4 + /CD8 + during EMs was significantly lower than healthy women (RR: − 0.13, I = 0%, p < 0.0001). However, there were insignificant deviations of CD4 + during PF between mild and severe EMs (RR: 1.65, I = 53%, p = 0.15), also there was an insignificant difference of CD4 + /CD8 + between mild and severe EMs (RR: − 0.09, I = 14%, p = 0.19). EMs might be closely related to local deviations of CD4 + T cells. Conclusion: There was no obvious correlation between EMs and systematic deviations of CD4 + T cells, EMs might be closely related to local deviations of CD4 + T cells. Further study on the functional deviations and subpopulation distribution of CD4 + T cells is urgently needed.