Background and Aim Platelets antigens, Anti-platelets antibodies, serum leptin measurement may be important in defining the pathogenesis of thrombocytopenic states.

Methods In this study we measured the platelets CD41, CD61, CD62P, Platelets IgG, IgM by flowcytometry and serum leptin by ELISA of 20 children diagnosed as ITP and 20 normal children as control.

Results We observed That there were no significant difference in white blood cells count, hemoglobin concentration between ITP patients and controls. Platelets count was significantly decreased, and mean platelet volume (MPV) was significantly increased in patients than controls P=0.000. The percentage of CD41expressing platelets was significantly lower in ITP children compared to controls (P=0.001) but the percentage of CD61expressing platelets was not significantly different between ITP patients and controls. Platelet activation marker CD62P was significantly expressed in patients than controls (0.000). Furthermore, the amount of CD62P per cell, represented by the MFI was significantly higher in patients than controls (0.000). The percentage of platelets associated IgM and IgG were was significantly increased in patients than controls (P=0.000). Also the MFI of IgM and IgG were significantly higher in patients than controls .Finally the concentration of serum leptin was increased in patients than controls (P=0.000) (table 2). There was a negative correlation between The platelets count and Platelets IgG (P= 0.000 and r= –0.88).

Conclusion We concluded that The demonstration of antiplatelet antibodies (PAIgG, PAIgM) and decreased detection of platelet surface antigens (CD41, CD61) in children with immune thrombocytopenic purpura (ITP) have a diagnostic and pathogenesis role.