Fig. 7.

Rab27a-deficient neutrophils have decreased CD44 surface expression. (A) The surface expression of the hyaluronan receptor CD44 in neutrophils was analyzed by flow cytometry. Left panel, representative histograms of CD44 expression in unstimulated neutrophils from Rab27a^ash/ash (ashen), Munc13-4^jinx/jinx (jinx), or wild-type (WT) mice after labeling with a monoclonal antibody directed at an extracellular epitope of CD44 (clone IM7) or isotype control (IC). Right panel, quantitative analysis of the MFI corresponding to CD44 expression in LPS-stimulated (100 ng/ml) and unstimulated neutrophils. Results are represented as means ± SEM (n = 6 mice). *, P < 0.03 versus the wild-type mice. (B) The adhesion of wild-type (WT) and Rab27a^ash/ash (ashen) bone marrow-derived neutrophils to hyaluronan was measured ex vivo as described in Materials and Methods. Results are means ± SEM from three independent experiments using cells from 3 wild-type and 4 ashen mice. *, P < 0.03 (nonparametric Mann-Whitney test). (C) Immunofluorescence analysis of the distribution of endogenous CD44 in ashen and wild-type neutrophils, unstimulated or treated with the chemotactic peptide fMLF. Data are representative of results of two independent experiments.