Abstract: Objective To study the expression of leukocyte-associated Ig-like receptor-1(LAIR-1) in children with immune thrombocytopenia (ITP), in order to explore the possible role of LAIR-1 in the pathogenesis of childhood ITP. MethodsExpression levels of LAIR-1 on CD4⁺ T cells, CD8⁺ T cells and CD19⁺CD20⁺ B cells of peripheral blood were measured in 40 children with ITP by flow cytometry. Serum level of solubility LAIR-1 (sLAIR-1) was measured using ELISA. Real-time PCR was used to measure LAIR-1 mRNA expression. Thirty-two healthy children served as the control group. Results The percentages of CD19⁺CD20⁺ B cells in the ITP group were significantly higher than in the control group (P<0.05). In contrast, the percentage of CD4⁺ T cells in the ITP group was significantly lower than in the control group (P<0.05). The expression levels of LAIR-1 on CD4⁺ T cells and CD8⁺ T cells were significantly lower in the ITP group than in the control group (P<0.05). Serum sLAIR-1 level and LAIR-1 mRNA expression in the ITP group significantly increased compared with the control group (P<0.05). ConclusionsLAIR-1 expression on CD4⁺ and CD8⁺ T cells decreases and serum sLAIR-1 level increases in children with ITP, suggesting that LAIR-1 may play an important role in immune imbalance in these children.