[CD22 signal abnormalities in the pathogenesis of immune related pancytopenia]

To investigate the expression of CD22 and its downstream signal molecule spleen tyrosine kinase (SYK) and their phosphorylation of B lymphocytes in patients with immune related pancytopenia(IRP), and to explore the role of CD22 in pathogenesis of IRP.

The expression of CD22, SYK and their phosphorylation, along with the expression of IgG and IgM, which obtained from B lymphocytes in peripheral blood of 46 patients with IRP(22 new diagnosed and 24 remitted patients returned to normal after treatment), 22 healthy controls and 12 chronic lymphocytic leukemia(CLL) patients from February to December 2014 were analyzed by flow cytometry. And the mRNA expression of CD22 in peripheral blood mononuclear cell was determined by real-time quantitative PCR.

The ratios of CD22+ cells and phosphorylated CD22(pCD22)+ cells of B lymphocytes in new diagnosed group (60. 03% ± 20. 94% 71. 32% ± 11. 16%) were significantly higher than those in remission group (46. 92% ± 20. 04%, 55. 82% ± 14. 42%), normal control group (46. 86% ± 17. 78%, 53. 28% ± 14. 76%) and CLL group (39. 74% ± 18. 96%, 59. 07% ± 17.09%) (all P <0.05). The ratios of phosphorylated SYK( pSYK) + cells in the four groups had the same trend (all P <0. 05). The ratio of pCD22+ cells/pSYK+ cells in new diagnosed group was significantly lower than that in normal control group and CLL group (27. 39 (5. 06 - 102. 70) vs 55. 95 (15. 25 - 298. 53), 56. 92(5. 60 - 228. 96), both P <0. 05), and pCD22+ cells positively correlated to pSYK+ cells ( r = 0. 341, P < 0. 05). The expression of IgG in new diagnosed group and remission group was significantly higher than that in normal control group, and the expression of IgM in new diagnosed group was significantly higher than that in normal control group and CLL group (all P <0. 05). The expression levels of CD22 mRNA in new diagnosed group was significantly higher than that in remission group, normal control group and CLL group (all P <0. 05).

The BCR signal pathway of B lymphocyte in IRP patients is enhanced, and the quantity and function of CD22 are increased, while which are still insufficient to inhibit B cell proliferation, and these may have some relationships with the pathogenesis of IRP. [Key words] Pancytopenia; Antigens, CD22; Immune related pancytopenia; Spleen tyrosine kinase; Phosphorylation