Fig. 4: Microglia nodules in MS are associated with activation of the classical complement pathway and are associated with membrane attack complex formation.

IHC stainings (C1qB, C3d and C5b9 in magenta, HLA in green). C1qB⁺ HLA⁺ microglia nodule (a) in MS and (b) in stroke. c Microglia nodules in MS and in stroke equally often express C1qB, quantified in n = 7 MS donors and n = 6 stroke donors. d HLA⁺ microglia nodule associated with a C3d⁺ axonal fragment in MS and (e) an HLA⁺ microglia nodule in stroke that is not associated with a C3d⁺ axonal fragment. f In MS, microglia nodules are more often associated with C3d⁺ axonal fragments than in stroke (p = 0.008), quantified in n = 7 MS donors and n = 6 stroke donors. IHC of (g) an HLA⁺ C5b-9⁺ microglia nodule in MS and (h) an HLA⁺ microglia nodule in stroke that is not C5b-9⁺. i In MS, microglia nodules are more often C5b-9⁺ than in stroke (p = 0.03), quantified in n = 6 MS donors and n = 6 stroke donors. Bar plots show mean value ± standard deviation. Significance was tested with a two-sided quasibinomial generalized linear model without correction for multiple testing, *p value < 0.05, **p value < 0.01. Source data are provided as a Source Data file.