CORRELATION OF THE EPITOPES DEFINED BY ANTI-CD26 MABS AND CD26 FUNCTION

To clarify the different anti-CD26 mAbs corresponding different functi ons of CD26, the correlation of the epitopes defined by anti-CD26 mAbs and the functions of CD26 have been studied. Using truncated, human-r at CD26 swap mutants and cross-blocking studies, 13 anti-CD26 mAbs wer e divided into 5 separate groups. These 5 epitopes were localized betw een the 1-247th, 248-358th, 359-449th (closer to the 359th amino acid) , 450-577th and 359-653th amino acid regions. MAbs against two of thes e five epitopes, the 248-358th and 359-449th amino acid regions, were associated with inducing modulation of CD26 and T-cell costimulation t hrough the CD3 pathway. Furthermore, mAbs against one of these epitope s, the 359-449th amino acid region, appeared to encompass the ADA bind ing domain. Analysing the avidity of each mAb to the CD26 molecule usi ng DPPIV enzymatic activity as an indicator, we found that the functio n of CD26 had little correlation with the avidity of anti-CD26 mAbs, s uggesting that distinct epitopes defined by anti-CD26 mAbs appeared to be associated with different functions of CD26. These results will be Fiery useful in the further definition of the functional domains of C D26. (C) 1998 Elsevier Science Ltd. All rights reserved.