| BACKGROUND AND AIMIdiopathic thrombocytopenic purpura is an autoimmune disorder characterized by a low platelet count and mucocutaneous bleeding in child period. Its incidence is 5/100thousand. ITP is generally acute, in majority, the illness resolves itself. However, the illness in 7%～28% developed into chronic, some of them should to accept Splenectomy. The low peripheral platelet concentration observed in ITP is the result of reduced platelet life span because of their early removal from the peripheral blood by the activated reticuloendothelial system of the spleen, liver or bone marrow, after their sensitization by autoantibodies that recognize their surface glycoprotein antigens . Apart from phagocytosis, destruction mechanisms include complement activation and direct cellular attack by T lymphocytes. The spleen is the site of autoreactive T- and B-cell interaction and activation, and autoreactive anti-platelet antibody production. Platelet destruction is also sited mainly in the spleen in most patients . While, we don't know how the platelets in sensitized organism run into splenic cord, as well as we don't know how to be identified and cleaned by macrophages. From 1990, many scholars discoved that the levels of plasmic P-selectin and E-selectin in ITP are increased, and activated endothelial cell may be the capital resource of solubility P-selectin. It means that endothelial cells in ITP splenic sinus vascellum are actived, spleen may be the capital resource of solubility P-selectin and solubility E-selectin. The actived endothelial cells in splenicsinus could capture the platelet and lymphocyte in blood circulation, the the lymphocytes were actived results in excessive destroy of platelet in ITP.In this study, we detected solubility selectins by ELISA, as well as the correlation between solubility selectins and platelet count in order to elucidate immunopathogenesis of ITP in children, develop the judgement of pathogenetic condition, the observation of therapeutic effect, the indication of splenectomy, the appraisal of prognosis.METHODS1. Peripheral venous blood were respectively drawed from 25 children with AITP and 15 CITP before treatment. 15 controls were from normal children who are similar with children with ITP in yeas of age and gender.2. Preparation of plasma: put 2ml peripheral venous blood into 0.2ml 1%EDTA, joggle, 2000r/min centrifugalizing to get the upper liquid for 10minutes and preserve it in -80℃refrifugalizing.3. Measurement of plasma solubility selectins: use ELISA to evaluate the levels of solubility selectins in plasma.4. Statistical assay: the data were dealt with SPSS 14.0 statistical software by analysis of Independent-Samples T-test, variance and linear correlation.RESULTS1. The levels of sE in plasma: the level of sE in ITP was 2.03±0.80 ng/ml, in AITP 2.18±0.87 ng/ml, in CITP 1.79±0.62 ng/ml and in controls 1.12±0.52 ng/ml.There was significant difference between ITP and controls(P=0.000). There was significant difference between AITP and controls(P = 0.000). There was significant difference between CITP and controls(P=0.009). There was no significant difference between AITP and CITP(P>0.05).2. The levels of sP in plasma: There was significant difference between ITP(610.11±200.67 ng/ml) and controls(843.62±256.80 ng/ml)(P=0.001). the level of sP/Plt in ITP was 33.00±11.74 ng/ml, in AITP 35.52±13.50 ng/ml, in CITP 28.79±6.41 ng/ml and in controls 3.40±1.12 ng/ml.There was significant difference between ITP and controls(P=0.000). There was significant difference between AITP and controls(P= 0.000). There was significant difference between CITP and controls(P=0.000). There was significant difference between AITP and CITP(P=0.04).3. The levels of sL in plasma: the level of sL in ITP was 3882.68±2107.31 ng/ml, in AITP 4044.04±2334.48 ng/ml, in CITP 3613.76±1704.16 ng/ml and in controls 3396.04±2096.46 ng/ml.There was no significant difference between ITP and controls(P =0.448). There was no significant difference between AITP and CITP(P>0.05).4. The correlation between plasma sP and platelet counts: There was significant correlation between plasma sP and platelet counts in ITP(r=0.540,p=0,000). There was significant correlation between plasma sP and platelet counts in AITP(r=0.654,p=0.000). There was no correlation between plasma sP and platelet counts in CITP(r=0.196,p=0.483).5. The correlation between plasma sP/Plt and platelet counts: There was significant correlation between plasma sP/Plt and platelet counts in ITP(r=-0.532,p=0.000). There was significant correlation between plasma sP/Plt and platelet counts in AITP(r=-0.464,p=0.019). There was no correlation between plasma sP/Plt and platelet counts in CITP(r=-0.834,p=0.000).6. The correlation between plasma sE and platelet counts: There was no significant correlation between plasma sE and platelet counts(r=-0.104,p=0.525).7. The correlation between plasma sL and platelet counts: There was no significant correlation between plasma sL and platelet counts(r=0.028,p=0.865). CONCLUSIONS1.The pathogenesis of ITP may include alteration of the level of solubility selectins. Exceeded expression of sP and sE results in excessive activation in T and B lymph cells in spleen, the cell immunity and humoral immunity were deranged in ITP.2. Exceeded expression of sP on endothelial cells of splenic sinusoid results in excessive capture of sensitized platelet in blood circulation, then they are destroyed and platelet in blood circulation are decreasing.3. The levels of sP/Plt in AITP were significant higher than mat in CITP. It suggests excessive activation in endothelial cells of splenic sinusoid in AITP, the destruction of platelets are significant.4. The findings of this study can give us some clues on elucidation the relation of ITP and selectins, however, it needs deep research.
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