Fig 2: Case 1 in area of low-background (see text). A, Only 1 label (ILT4; pink) is shown in this image that highlights KCs within the lobules of case 1 that showed marked KC hypertrophy. B, This panel simultaneously shows 2 labels, CD31 highlights the sinusoidal endothelium (red) and C4d (fluorescent green); note the lack of yellow staining that would indicate C4d deposition on the CD31+ sinusoidal endothelium. Instead, the C4d is highlighting sinusoidal cells. C, This panel simultaneously shows 2 labels, ILT4 (pink) and CD163 (turquoise). The staining shows overlap within the KCs, but not necessarily in the same subcellular location. D, This panel simultaneously shows all 4 labels, CD31 (red), ILT4 (pink), C4d (fluorescent green), and CD163 (turquoise). The overlapping staining of C4d, CD163, and ILT4 appears white in this combined image, which localizes to KCs. ILT4, immunoglobulin-like transcript-4; KC, Kupffer cell.

Fig 3: Higher magnification of the lobule from case 1. Note the marked KC hypertrophy (upper left panel; arrows), some of which contained intra-cytoplasmic debris and occasional cells. C4d staining (right panel) showed cytoplasmic labeling for C4d in enlarged KC (pink staining), which also stained strongly for MHCII, as expected (inset; brown staining). This observation led us to conclude that some C4d is deposited or contained within KC. The bottom left panel shows a normal human liver stained for CD34 (cyan) that highlights the portal microvascular and ILT4 (green) that highlights KCs within the lobules. The bottom right panel adds CD163 (red) that highlights KCs, which overlaps with the green ILT4 stain resulting in a yellow-orange color within the sinusoids indicating that CD163+ KC also express ILT4. ILT4, immunoglobulin-like transcript-4; KC, Kupffer cell; MHCII, major histocompatibility complex II.