ANTI-T11.1 AND ANTI-T11.2 MONOCLONAL-ANTIBODIES PLAY A DIFFERENT ROLEIN CD2-MEDIATED SIGNAL-TRANSDUCTION

We comparatively evaluated (Ca2+)(i) mobilization after triggering wit h a stimulatory pair of CD2 (CD2.9, anti-T11.1+CD2.1, anti-T11.2) or C D3 mAbs in the differentiated T-cell line Jurkat, using INDO-1 labelin g and cytofluorimetry. The results obtained showed different (Ca2+)(i) mobilization kinetics following CD2 or CD3 stimulation (the former be ing slower than the latter), not due to different association kinetics of mAbs. In a nonreciprocal manner, however, preliminary interaction with CD2.1 (anti-T11.2) followed by CD2.9 (anti-T11.1) induces a rapid (Ca2+)(i) rise, similar to CD3 stimulation, as shown by preincubation experiments. There is no interference between CD2.9 and CD2.1 mAb bin ding. CD2.1 mAb by itself is unable to induce (Ca2+)(i) mobilization; in addition, preincubation with CD2.1 mAb did not modify the CD2, CD3, CD45, or CD28 immunoprecipitation patterns. Triggering of the epitope recognized by CD2.1 mAb may favor, possibly via conformational change s of CD2 molecule or (Ca2+)(i)-unrelated metabolic effect(s), optimal signal transduction.