Protein and mRNA expression of matriptase by peripheral blood mononuclear cells. (A) Flow cytometry of PBMCs obtained following Ficoll centrifugation of venous blood from healthy consenting donors (B) exhibit matriptase surface expression (solid line indicates matriptase; dashed line, isotype control; and dotted line, intrinsic fluorescence). (C) Multicolor flow cytometry demonstrates significantly higher expression of matriptase on monocytes (solid line) and B cells (long dashes), compared with T cells (dotted). The control for intrinsic fluorescence control is shown (short dashes). (D) Matriptase expression quantified by qRT-PCR for the total mononuclear cell population immediately ex vivo (PBMC), and individual cell populations purified using magnetic activated cell sorting (MACS) magnetic beads to obtain CD3⁺ T cells, CD19⁺ B cells, and CD14⁺ monocytes. Data are shown for cells either immediately after purification (gray bars), after 8 hours in culture unstimulated (hatched bars), or after stimulation of monocytes, B cells, and T cells with IFN-γ and LPS, anti-IgG/IgM, or PMA and ionomycin, respectively (crosshatched bars). Values are corrected for RNA content by comparison to 18S ribosomal RNA. Data are shown as mean ± SD (n = 6). The observed reductions in matriptase expression by monocytes were statistically significant (paired t test, P < .05).