Stereotactic biopsy of an active multiple sclerosis lesion. Immunocytochemical analysis and neuropathologic...

Stereotactic biopsy of an active multiple sclerosis lesion in a 23-year-old patient with unilateral symptoms and an isolated high-signal-intensity magnetic resonance abnormality yielded 10 serial tissue cores (1.0 x 0.5 cm) spanning 40 mm within and around the lesion. We performed semiquantitative analysis of lymphocyte phenotype, using antisera to CD3, CD4, CD8, and CD22 molecules, in 11 separate perivascular cuffs in three tissue sections from the lesion edge. Total cells in the cuffs varied from 10 to 100; ratios of CD4+/CD8+ cells in individual cuffs varied from 1.3 to 4.7. Although intense parenchymal infiltrates bordered the least cellular cuffs, parenchymal and perivascular cell phenotypes were indistinguishable, arguing against selective trafficking of lymphocytes into tissue. Individual microfoci of cells displaying CD45RA, CD25, and TQ1 antigens were present. The remarkable phenotypic heterogeneity of T lymphocytes in the multiple sclerosis lesion border is consistent with exposure in situ to a diversity of differentiating stimuli. Histologic demyelination correlated very closely with the signal-intensity abnormality observed on magnetic resonance imaging. These studies provide unusual insight into the histologic and immunocytochemical morphologic appearance of the active multiple sclerosis plaque.