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 immunomagnetic 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.