Characterization of murine CEACAM1 in vivo reveals low expression on CD8(+) T cells and no tumor growth modulating activity by anti-CEACAM1 mAb CC1

McLeod, Robbie L.; Angagaw, Minilik H.; Baral, Toya Nath; Liu, Liming; Moniz, Raymond Joseph; Laskey, Jason; Hsieh, SuChun; Lee, Mike; Han, Jin-Hwan; Issafras, Hassan; Javaid, Sarah; Loboda, Andrey; Sadekova, Svetlana; O'Connor, Joann A.; Tse, Archie; Punnonen, Juha

In light of conflicting and partially opposing observations regarding the role of CEACAM1 in antitumor responses, we endeavored to further characterize CEACAM1 expression combined with evaluation of its potential tumor growth modulating properties using an anti CEACAM mAb. Anti-mouse CEACAM1 Ab CC1 has been widely used in preclinical studies to evaluate CEACAM1 biology in vitro and in vivo and several of the studies demonstrating immunomodulatory properties of CEACAM1 in vivo have been performed using CC1 [17, 19, 21, 23] . The mAb was initially generated by immunizing SJL/J mice with purified BALB/c intestinal brush border membranes and subsequently purified from a hybridoma derived by fusion of SP20 cells with spleen cells from the immunized mice [17] . While detailed functional characterization of CC1 Ab has been carried out in multiple studies, little information is available on the binding characteristics in vitro. Moreover, no data have been reported regarding the pharmacokinetic properties of CC1 in tumor bearing cancer models. In the present study, we sought to characterize expression profile of CEACAM1 and the effects of CC1 Ab in syngeneic mouse tumor models in vivo.