Macrophages from a PAPA syndrome patient have increased filopodia-like membrane projections. (A) Image of pyoderma gangrenosum on the PAPA patient’s right leg. (B) Reverse strand sequence traces from the PSTPIP1 genomic DNA sequencing of the patient, his mother, and his father. The diagram shows the location of the mutation at the DNA and protein level. (C) Western blots of lysate from control and PAPA macrophages was probed with mouse anti-PSTPIP1 and rabbit anti-β-tubulin (loading control) antibodies to determine relative PSTPIP1 expression. Arrowheads indicate location of molecular weight markers (kDa). PSTPIP1 expression in the PAPA patient macrophages was normalized to controls for quantification. (D) Representative images of podosomes and filopodia-like membrane projections in PAPA and control macrophages. Podosomes and filopodia-like structures were stained with anti-vinculin antibody (green) and rhodamine phalloidin (magenta). Arrowheads indicate filopodia-like projections in PAPA macrophages. (E-F) Quantification of the percentage of macrophages shown in (D) that form podosomes (E) and filopodia-like projections (F). Scale bar, 20 μm. All values are mean ± SEM from 3 (E,F) or 4 (C) independent experiments. **P < .01; ***P < .001 as determined by an unpaired Student t test (E,F) or paired Student t test (C).