ABSTRACT
<p><b>OBJECTIVE</b>To observe the expression change of signal regulatory protein alpha1 (SIRPalpha1) in autoimmune hepatitis (AIH) and approach the relationship between SIRPalpha1 and the extent of inflammation.</p><p><b>METHODS</b>Immunohistochemistry is used to detect the expression of SIRPalpha1 in the paraffin section preparations of 33 AIH and 10 normal hepatic tissue.</p><p><b>RESULTS</b>SIRPalpha1 is positive or weakly positive expressed in AIH. The staining is localized in the cytoplasm of Kupffer cells in the hepatic sinusoid with focal distribution. It is negative in normal hepatic tissue. In light AIH, it is negative or weakly positive expressed with a 36.4 percent of the positive rate (4/11). The positive or strong positive expression is found in the moderate AIH with an 84.2 percent of the positive rate(16/19). There is statistical significance between both light AIH, moderate AIH and severe AIH (P less than 0.001) and moderate AIH and light AIH (P less than 0.001). There is no statistical significance between both light AIH and severe AIH (P = 0.145 ) and moderate AIH and severe AIH (P = 0.084).</p><p><b>CONCLUSIONS</b>As a negative regulatory factor, the expression of SIRPalpha1 in hepatic sinusoid Kupffer cells is some associated with the extent of AIH.</p>