Fig. 1

Mast cells accumulate in the surrounding of degenerating motor neurons in the spinal cord of ALS patients. A Representative immunohistochemical confocal images of mast cells infiltrating into the ventral horn of lumbar spinal cord of autopsy ALS subjects. Left panels show the expression of c-Kit+ (red) and chymase+ (green) mast cells displaying typical granular (white arrows) and non-granular (white arrowheads) morphology in the surroundings of degenerating motor neurons (white lines). The right panels show the co-expression of chymase (green) and tryptase (red) in mast cells. Magenta squares show high magnification 3D reconstructions of both, small non-granular and degranulating cells. B Representative high magnification confocal phenotyping of mast cells in the spinal cord of ALS subjects. Upper panels show a granular mast cell co-expressing c-Kit (red) and tryptase (green). Lower panels show a typical degranulating mast cell that co-express tryptase (red) and chymase (green). C Representative microphotograph of non-granular small mast cells with none or few granules that typically express c-Kit (red), chymase (green), and Cox-2 (magenta). D Representative confocal image of the immunohistochemical analysis performed in autopsy control donors, showing only a few small non-granular cells expressing c-Kit (white arrowhead) in the surroundings of motor neurons (white lines). The white square shows a high magnification 3D reconstruction of typical non-granular cells expressing c-Kit (red). E The graphs show the quantitative analysis of c-Kit+ (left) and tryptase+/chymase+ (right) cells in the area that surrounds motor neurons in the ventral horn of the lumbar spinal cord of ALS subjects compared to control donors. Quantitative data are expressed as mean ± s.e.m. Data were analyzed by a two-tailed Mann–Whitney test, with ***p < 0.0001. Scale bars: 20 µm and 10 µm in (A, D) and 5 µ in (B, C)