. ▁T X A 2 ▁increases ▁plate let ▁aggreg ation , ▁prom otes ▁de gr an ulation ▁and ▁stim ul ates ▁plate let ▁activation . ▁In hib ition ▁of ▁CO X 1 , ▁as ▁with ▁ac et yl sal icy lic ▁acid , ▁and ▁in hib ition ▁or ▁absence ▁of ▁G PI I b / III a ▁re ceptor , ▁as ▁seen ▁in ▁Gl anz mann ' s ▁th rom bas then ia , ▁will ▁reduce ▁plate let ▁aggreg ation ▁in ▁response ▁to ▁a rach id onic ▁acid . ▁ ▁COL test ▁Col lagen ▁is ▁added ▁to ▁the ▁sample - sal ine ▁mix , ▁and ▁bind s ▁to ▁col lagen - re cept ors ▁on ▁plate lets . ▁This ▁leads ▁to ▁a ▁release ▁of ▁a rach id onic ▁acid , ▁which ▁is ▁converted ▁to ▁the ▁pot ent ▁plate let ▁activ ator ▁T X A 2 . ▁COL test ▁is ▁sensitive ▁to ▁in hib ition ▁of ▁CO X 1 ▁and ▁G PI I b / III a ▁and ▁to ▁Gl anz mann ' s ▁th rom bas then ia . ▁ ▁R IST O test ▁R ist oc et in ▁forms ▁complex es ▁with ▁von ▁Wille brand ▁factor ▁( v WF ) ▁that ▁bind ▁to ▁the ▁g ly cop rote in ▁Ib ▁( GP 1 b ) ▁re cept ors ▁on ▁plate lets , ▁causing ▁plate let ▁activation ▁and ▁aggreg ation . ▁ ▁Red u ced ▁or ▁absent ▁aggreg ation ▁in ▁response ▁to ▁r ist oc et in ▁can ▁be ▁caused ▁by ▁a ▁lack