Contribution of platelet LTC₄S to cysLT production by peripheral blood granulocytes. (A) Western blot analysis of platelets for LTC₄S protein in 3 ATA controls and 4 subjects with AERD. (B) Removal of adherent platelets by trypsinization is shown cytofluorographically for a subject with AERD. Isolated granulocytes were stained for CD45 and analyzed for their expression of CD61 before trypsinization (black line) and again after trypsinization (solid gray). (C) Conversion of LTA₄-ME to LTC₄-ME by washed platelets (left section of panel) and by granulocytes (right section of panel) without and with trypsinization to remove adherent platelets from subjects with ATA (gray columns; n = 6) and AERD (black columns; n = 7). (D) A23187-induced production of LTC₄ (top) and the sum of all 5-LO pathway products [LTB₄, LTC₄, LTD₄, (5,6)-dihydroxy-7,9-trans-11,14-cis-eicosatetraenoic acid [5,6-DiHETE], and 6-trans-LTB₄; bottom] by granulocytes without and without trypsinization to remove adherent platelets from subjects with ATA (n = 8) and AERD (n = 10). Data in panels C and D are expressed as mean +SEM (★P < .05, ★★P < .01).