ABSTRACT
<p><b>AIM</b>BLT1 and BLT2 were both recently cloned and identified as two subtypes of leukotrine B4 (LTB4) receptors. With the usage of U-75302 and LY255283, the specific antagonists of BLT1 and BLT2 respectively, the involvement of BLT1 and BLT2 in the inflammatory and immunological responses was in vitro explored.</p><p><b>METHODS</b>(1) To investigate inhibition of U-75302 and LY255283 on the proliferation of rat synovial cells, 3H-TdR incorporation into the cells was quantified. (2) Flow cytometric assay for interferon-gamma (IFN-gamma) and interleukine 4 (IL-4) profiles in CD4+ T lymphocytes from rat spleen was carried out to determine the ratio of Th1/Th2.</p><p><b>RESULTS</b>(1) For inhibition on rat synovial cells proliferation, U-75302 exerted its effect only at a high concentration of 10 micromol/L and LY255283 at the concentrations of 10 micromol/L-10 micromol/L. (2) Both U-75302 and LY255283 could elevate the percentage of Th2, but could not influence that of Th1.</p><p><b>CONCLUSION</b>BLT1 and BLT2 were involved in the synovial cells proliferation change the ratio of Th1/Th2. Their meaning served as targets for prevention and treatment of infectious diseases should be emphasized.</p>