CD40LG and poliomyelitis: While the white matter harbors the characteristic, phagocytic, amoeboid microglia/macrophages[64] involved in the stripping of myelin sheaths leading to demyelination[4], grey matter shows numerous activated microglia/macrophages trying to reinstate homeostasis but are unable to achieve the said goal in the absence of homeostatic signals received from CD40L expressed on CD4+ T cells and thus result in persistent grey matter inflammation in the form of poliomyelitis, which was also observed in CD4-/- mice previously only at the acute phase[9].