Characterization of a novel activation antigen on porcine lymphocytes recognized by monoclonal antibody 5A6/8

In this report, we describe the characterization of a novel activation antigen on porcine lymphocytes recognized by mAb 5A6/8. This antigen was detected on B and T cells 24 h after treatment with various stimuli. It was also found on alveolar macrophages, and at low levels on untreated monocytes. MAb 5A6/8 precipitated two bands of 45 and 50 kDa under non-reducing conditions, and of 22 and 28 kDa under reducing conditions. The cellular distribution, expression kinetics and/or molecular size of the 5A6/8 antigen differ from those of other known lymphocyte activation antigens. MAb 5A6/8 was able to inhibit lymphocyte proliferative responses driven by different stimuli, suggesting a role for this molecule in the events that lead to lymphocyte activation.