Lymphocytes expressing α1β1 integrin (very late antigen-1) in peripheral blood of patients with arthritis are a subset of CD45RO⁺ T-cells primed for rapid adhesion to collagen IV

We report that very late antigen-1 (VLA-1⁺) CD3⁺CD45RO⁺ T-cells are selectively segregated from VLA-1^- peripheral blood (PB) mononuclear cells (MC), in which CD3⁺ T-cells are evenly CD45RO⁺ and CD45RO^-, when PBMC are stained with a monoclonal antibody (mAb) to VLA-1 and passaged on immuno-magnetic columns. In contrast, both VLA-1⁺ and VLA-1^- MC isolated from synovial fluid (SF) are mainly CD45RO⁺CD3⁺ T-cells. VLA-1⁺ MC formed 13 ± 5.3% of MC eluting from columns loaded with PBMC of patients with seropositive rheumatoid arthritis (n = 6) and 2.3 ± 1.6% of patients (n = 4) with other arthritides (P < 0.022). Importantly, only the VLA-1⁺ MC from PB and SF adhered to collagen IV upon triggering with phorbol 12-myristate 13-acetate. Moreover, adhesion and migration on collagen IV were preferentially maintained in lines cultured from VLA-1⁺ T-cells, and both were inhibited by mAb to the VLA-1 α1 I domain. These results suggest that VLA-1⁺ CD45RO⁺ T-cells in patients with arthritis could play a role in both systemic and local inflammation by rapidly adhering to collagen IV.