FUNC: This antibody directly induces the binding of T cells to purified ICAM-1. Using an in vitro-translated CDlla cDNA deletion series, the MEM-83 activation epitope was mapped to the "I" domain of the LFA-1 alpha subunit. The studies have therefore identified a novel LFA-1 activation epitope mapping to the I domain of LFA-1, which could play a role in the regulation of LFA-1 binding to ICAM-1, Flow Cytometry: 1 ug/ml.