ABSTRACT
<p><b>OBJECTIVE</b>To investigate the expressions of costimulators on peripheral T and B lymphocytes in patients with idiopathic thrombocytopenic purpura (ITP).</p><p><b>METHODS</b>The expression of B7-CD(28) and CD(40) of peripheral lymphocytes was measured by flow cytometry in 21 ITP patients and 9 normal subjects. The expression of PAIgG was measured by ELISA method.</p><p><b>RESULTS</b>The expression of CD(4)(+)CD(28)(+) was lower in ITP patients than in normal controls, but the expression of CD(86)(+) and CD(86)(+)CD(19)(+) was higher in ITP patients than in normal controls, while the expression of CD(80)(+), CD(40)(+), CD(28)(+), CD(19)(+)CD(86)(+), CD(19)(+)CD(40)(+), CD(4)(+)CD(28)(+)/CD(4)(+), CD(19)(+)CD(80)(+)/CD(19)(+) and CD(19)(+)CD(40)(+)/CD(19)(+) in ITP patients was normal. The PAIgG level was higher in 16 patients with a mean of (184.62 +/- 38.00) ng/10(7) plt. A positive correlation was found between PAIgG and CD(19)(+)CD(86)(+)/CD(19)(+) expression.</p><p><b>CONCLUSION</b>There is no deficiency in expression of CD(28) on CD(4)(+) T lymphocytes in ITP patients. The change of CD(86) expression on B lymphocytes is possibly involved in pathophysiology of ITP, which may provide a theoretical instruction for ITP patients immunological therapy.</p>