Objective To investigate the levels of γδ T cells and their subpopulations in bone marrow(BM)of patients with myelodysplastic syndrome(MDS),it aims to explore the immune deficiency status of BM microenvi-ronment in MDS patients.Methods BM samples were collected from MDS patients before and after treatment,as well as from normal donors.Multicolor flow cytometry was utilized to detect bone marrow γδ T cells and subpopulation levels.The changes of the T cell subsets after treatment were also analyzed.Results The levels of BM γδ T cells and follicular helper γδ T cells from MDS patients were significantly lower than those of normal donors(P<0.05).Among γδ T cells at different stages of differentiation,only the frequencies of na?ve γδ T cells from MDS patients decreased significantly(P = 0.037),and there was no significant difference observed about central memory,effector memory,and terminally differentiated γδ T cells in MDS patients compared to normal donors(P>0.05).Although there was a slight decrease in PD1+γδ T cells and an increase in TIM3+γδ T cells,these differences were not statistically significant(P>0.05).In patients who achieved a curative effect,the proportions of γδ T cells and naive γδ T cells increased significantly after treatment,and the effector memory γδ T cells decreased significantly after treatment(P<0.05).After treatment,85.71%(6/7)of MDS patients showed a decrease in γδ+TIM3+ T cell levels to varying degrees.Conclusions The levels of γδ T cells and their subpopulations in the BM microenvironment of patients with MDS exhibit varying degrees of abnormalities.However,in patients who receive effective treatment,these abnormal γδ T cells can recover.By detecting the levels of γδ T cells and subpopulations,we can gain insights into the immune deficiency status of MDS.This information might serve as an indicator to assess treatment efficacy and provide valuable insights for anti-tumor immunotherapy.