Cell Surface Expression of CD11b/c and CD49d. The effect of antigen challenge on the expression of CD11b/c β 2-integrin and CD49d β 1-integrin on circulating neutrophils. Integrin expression on the cell surface of neutrophils was determined by measuring the mean fluorescence intensity (MFI) of specific antibody binding for each integrin. Ovalbumin sensitized rats received either naïve antigen (BSA □ n = 5), feG (■ n = 6), sensitizing antigen (OA ; n = 6), or OA + feG (; n = 6) 18 h before harvesting the cells. Significance: # > BSA; * < OA.