Identification and functional characterization of mouse CD29 with a mAb

The beta 1 integrin subfamily, alternatively called very late activation antigen (VLA), has been implicated in various cellular functions. In this study, we generated a mAb against the mouse beta 1 subunit (CD29) to examine the functional property of mouse VLA proteins. After immunization with affinity-purified mouse VLA-4 (alpha 4 beta 1), a hamster mAb, HM beta 1-1, was established by screening mAb that reacted with alpha 4-negative neuroblastoma C1300. The antigen defined by HM beta 1-1 was widely distributed in various mouse cell lines and HM beta 1-1 immunoprecipitated a 110-120 kDa protein common to VLA-1 and VLA-6, indicating that HM beta 1-1 recognizes the beta 1 subunit of mouse integrins. We then examined the inhibitory effect of HM beta 1-1 on VLA-dependent cell adhesion and activation. HM beta 1-1 blocked the adhesion of mouse tumor cell lines to extracellular matrix proteins including collagen, laminin and fibronectin. Moreover, splenic T cell proliferation induced by anti-CD3 mAb and allogeneic mixed lymphocyte response were strongly inhibited by HM beta 1-1 in combination with an anti-LFA-1 mAb. We conclude that HM beta 1-1 reactive with mouse CD29 can inhibit VLA-dependent cellular functions and, thus, would be useful for studying the physiological role of beta 1 integrins in vivo.