Natalizumab and PML in MS
Natalizumab, an effective therapy for multiple sclerosis, can lead the ordinarily innocuous JC virus to cause progressive multifocal leukoencephalopathy (PML) if it is too potent in its ability to block ingress of T cells into the CNS. It binds to very late activation antigen-4 (VLA-4) on immune cells, which no longer bind to CNS endothelium and can’t cross the blood-brain barrier. It lowers the number of CSF T cells by at least 10-fold and B cells by 6-fold.
Jul. 23, 2021