SFA-1/PETA-3 (CD151), a member of the transmembrane 4 superfamily, associates preferentially with alpha 5 beta 1 integrin and regulates adhesion of human T cell leukemia virus type 1-infected T cells to fibronectin.

In this study we have analyzed the adhesion molecules associated with and the biologic function of SFA-1/PETA-3 (CD151) in human T cell leukemia virus type 1 (HTLV-1)-infected T cells and in freshly isolated adult T cell leukemia (ATL) cells using an anti-CD151 mAb. The anti-CD151 mAb coprecipitated alpha 5 beta 1 integrin from HTLV-1-infected T cells. Conversely, an anti-alpha 5 integrin mAb coprecipitated CD151. The anti-CD151 mAb inhibited the adhesion of HTLV-1-infected T cells to fibronectin but did not have any effect on their adhesion to laminin, collagen type I, or collagen type IV. Moreover, antisense CD151 oligonucleotide-treated HTLV-1-infected T cells showed significant inhibition of adhesion to fibronectin. These findings showed that the CD151 molecule was associated with the alpha 5 beta 1 integrin molecule and that it enhanced alpha 5 beta 1 integrin-mediated adhesion to fibronectin. In addition, the expression levels of CD151, alpha 4 beta 1 integrin, and alpha 5 beta 1 integrin on ATL cells from lymph nodes of lymphoma-type ATL patients were significantly higher than those on circulating ATL cells from leukemia-type ATL patients. This suggests that the increased expression of these integrins may contribute to lymphoma formation through the adhesion of ATL cells to the extracellular matrix and dendritic cells, rather than contributing to transmigration.