Analysis of crossreactivity of novel anti-CD26 mAbs with humanized anti-CD26 mAb. Jurkat-CD26WT cells were pretreated with unlabeled humanized anti-CD26 mAb (YS110) or human control IgG, and then treated with the hybridoma supernatant (clone 1, 5, 11, 16, 18 or 19) or purified mouse anti-CD26 mAb (1F7 or 5F8), and subsequently stained with PE-labeled anti-mouse Ig pAb. For staining with humanized anti-CD26 mAb, cells were stained with Alexa Fluor 647-labeled YS110 after pretreatment with unlabeled YS110. Data were analyzed by flow cytometry, and the percentage of mean fluorescence intensity (MFI) after YS110 blocking to MFI after control IgG blocking is shown. Data shown are repeated twice with similar results.