Here we show that the crawling of patrolling monocytes on the inflamed endothelium is regulated by MT4-MMP-dependent cleavage of αM integrin (Itgam/CD11b), and that this monocyte subset contributes to the accumulation of Mafb+apoptosis inhibitor of macrophage (AIM)+-expressing macrophages in incipient plaques and to overall AT progression. This evidence concerns the gene CD5L and ataxia telangiectasia.