ObjectiveTo investigate the changes in lymphocyte subsets and natural killer (NK) cells before splenectomy in patients with primary immune thrombocytopenia (ITP) who have no response to corticosteroid therapy or experience recurrence after drug withdrawal, as well as their association with early ITP recurrence after splenectomy. MethodsA total of 32 patients with ITP who were treated with splenectomy in The People′s Hospital of Bao′an District from January 2009 to December 2015 and followed up for 3-60 months were enrolled and divided into early recurrence group (with recurrence within 6 months after splenectomy and platelet count <30×109/L) and response group (platelet count >30×109/L after splenectomy, two-fold increase compared with before splenectomy) according to the outcome of splenectomy. Flow cytometry was used to measure the percentages of peripheral blood lymphocyte subsets (CD3+CD4+, CD3+CD8+, CD3+CD4+/CD3+CD8+, and CD3-CD19+) and CD56+CD16+ NK cells before splenectomy. The t-test was used for comparison of continuous data between groups and the chi-square test or Fisher′s exact test was used for comparison of categorical data between groups. ResultsThere were 11 patients (11/32, 34.4%) in the early recurrence group and 21 (21/32, 65.6%) in the response group. Compared with the response group, the early recurrence group had a significantly lower percentage of CD3+CD4+ (21.7%±5.4% vs 32.6%±4.1%, t=6.39, P=0.015) and a significantly lower CD3+CD4+/CD3+CD8+ ratio (0.65±0.21 vs 1.29±0.36, t=3.92, P=0003), as well as a significantly higher percentage of ]CD3+CD8+ T cells (34.5%±5.9% vs 26.8%±6.6%, t=-3.20, P=0.030) before splenectomy. There were no significant differences in CD3-/CD16+CD56+ ratio and the percentage of CD3-CD19+ T cells between the two groups (both P>0.05). ConclusionITP patients with a low percentage of CD3+CD4+ T cells and a low CD3+CD4+/CD3+CD8+ ratio before splenectomy tend to experience recurrence after surgery, which suggests that abnormal T lymphocyte subsets can be used as one of the reference indices for predicting the clinical outcome of splenectomy in ITP patients.