Differential expression of high-affinity α4 integrins in murine tissues. (A) The percent of leukocytes exhibiting specific VCAM-1/Fc binding, indicative of expression of high-affinity α4 integrin, was determined by subtracting IgG from VCAM-1/Fc binding. Specific VCAM-1/Fc binding to leukocytes and leukocyte subtypes isolated from various tissues is shown. Data are expressed as mean ± SEM of values obtained from at least 4 mice. (B) The expression of α4 integrins on the cell surface of spleen and lymph node leukocytes was determined by flow cytometry. The MFI of immunostaining from a representative experiment is shown. (C) IgG and VCAM-1/Fc binding (left and right panels, respectively) to IgD⁺ and IgD^- populations of IgM⁺ bone marrow B cells. The MFIs determined by flow cytometry are indicated. Representative data from 1 of 4 experiments are shown.