- The number and percentage of whole blood CD8+ CD62L- CD45RA- effector memory T cells were significantly increased in natalizumab-treated multiple sclerosis (MS) patients, with the greatest increase observed in the group at high versus low risk of progressive multifocal leukoencephalopathy (PML). However, CD4+ CD62L+ T-cell counts did not differ across PML risk groups in natalizumab-treated patients.
Why this matters
Early studies of cryopreserved T cells from people treated with natalizumab have suggested that the number of CD4+ CD62L+ T cells decreases before PML develops.
CD62L is an important surface adhesion molecule which allows T cells to recirculate into secondary lymphoid organs such as lymph nodes.
The current study indicates that phenotyping CD8+, as opposed to CD4+, peripheral T cells might be more informative for assessing PML risk in natalizumab-treated MS patients.