Expression of the HML-1 epitope on human monocytes is independent of alphaE integrin mRNA

Interferon gamma (IFN gamma)-mediated activation of the myelomonocytic cell line HL-60 and peripheral blood monocytes will induce expression of an epi tope for the monoclonal antibody which recognizes human alpha E beta 7 inte grin, HML-1. Here, we found that the anti-human alpha E beta 7 monoclonar a ntibody Ber-ACT8 did not recognize IFN gamma-stimulated, HML-1 positive HL- 60 cells. Culture of brood monocytes with IFN gamma also induced expression of HML-1 but not Ber-ACT8 epitopes. Moreover, migration of monocytes acros s a monolayer of human airway epithelial cells rapidly induced expression o f HML-1, with no detectable Ber-ACT8 staining. Using two different sets of primers specific for the human alpha E integrin gene, we were unable to det ect alpha E mRNA within HL-60 cells or isolated monocytes by reverse transc riptase polymerase chain reaction methods. We conclude that reactivity of t he HML-1 antibody for HL-60 cells and monocytes does not correspond with th e expression of the alpha E integrin subunit, and instead detects a marker for cellular activation.