Fig 1: BTK-induced pyroptosis of uninfected ATII cells in Patient 3(A) Graphic. Expression of BTK and downstream pyroptotic/NLRP3 inflammasome pathway components in latticework bodies leads to cell fusion and subsequent disruption and emptying of the cells and latticework. Stages labeled 1–4 show an initial stage 1 of a largely intact cell and latticework with cell disruption and progressive emptying of the latticework in stages 2 and 3 to create cavities and walls in stage 4, formed from cell remnants and residual cell membranes. This asynchronous process imparts a characteristic honeycombed and moth-eaten appearance to foci composed of cavities with cell remnants, lined by residual cell membranes and cells at earlier stages of pyroptosis.BTK. (B-E) Red-stained BTK+ cells and structures. Hematoxylin counterstain. Numbers correspond to stages shown in the graphic. (B) Alveolar space filled with fused BTK+ cells. (C) Cavities and walls with cells at an earlier stage numbered to correspond to BTK+ cells at the stages shown in the graphic. (D) Arrows point to remnants of BTK+ cells in cavities; arrowheads to residual cell membranes that constitute cavity walls. (E) Honeycombed space with BTK+ cells at earlier stages of pyroptosis fused to cell remnants and membranes of BTK+ “ghosts.”CASP1. (F, G) Brown-stained CASP1 cells and structures, immunohistochemical staining, hematoxylin counterstain (F1, G1). CASP1+ cells and structures are red and hematoxylin is blue in deconvoluted images (F2, G2). (F, G) Arrows point to cell remnants in cavities; arrowheads point to residual cell membranes in the cavity walls. LW= latticework. The loss of CASP1 and cell contents is reflected in the loss of detectable staining in the deconvoluted images.IL-1ß. (H-K) Red-stained IL-1ß+ cells and structures. Hematoxylin counterstain. (H) Box encloses IL-1ß+ cells lining cavities. (I) Magnifier 2X view showing porous latticework (arrow) and residual membranes (arrowheads). (J) Arrowheads point to residual cell membranes in fused cells created by emptying (blurred staining) of IL-1ß. (K) Arrow points to emptying IL-1ß + cell fused to remnants of cells and latticework.GSD. (L-O) Red-stained GSD+ cells and structures. Hematoxylin counterstain. (L) Arrows point to two early stage 1 fused GSD+ cells. (M) Formation of cavities by emptying and disruption of GSD+ cells and latticework (arrows M1, 2) leaving walls of residual cell membranes (arrowheads in M2). (N 1–3) GSD+ cell and latticework remnants of fused cells in cavity walls. Porous remnants in (N2) shown at 2x magnification in (N3). (O1) Honeycombed space with cavities and walls with GSD+ cell and latticework remnants. (O2) Deconvoluted image, GSD is red, hematoxylin is blue. Boxes in O1 and O2 correlate the darker staining blue-black latticework bodies and pores with a hematoxylin-stained component.NINJ1. (P-S) Brown-stained cells and structures. Hematoxylin counterstain. (P) Box encloses cavities, cell remnants and residual membranes. Arrow points to NINJ+ disrupted cell. (Q) Box encloses cavity with NINJ1+ cells/latticework. Arrow points to emptying porous latticework. (R) Arrowheads point to NINJ+ residual cell membranes. (S) Contrasting cytopathology of an enlarged necroptotic (ncpt) cell with largely intact NINJ1+ porous latticework and owl’s-eye like nucleus surrounded by NINJ1+ largely disrupted cells, cell remnants, latticework bodies, pores, and residual membranes.