Melanin-laden macrophages in cerebrospinal fluid in Vogt-Koyanagi-Harada syndrome

To identify basophilic granules in the cytoplasm of macrophages in cerebrospinal fluid (CSF) smears from patients with Vogt-Koyanagi-Harada (VKH) syndrome as melanin pigment.

Morphological and immunocytochemical studies were performed on CSF smears obtained from 7 patients with VKH syndrome. Specimens were stained with May-Grünwald and evaluated by a silver impregnation method (Fontana-Masson staining). For immunocyto-chemical study, the smear was reacted with mouse anti-human melanoma cell (HMB-45) monoclonal antibody.

Basophilic granules were detected in the cytoplasm of macrophages in CSF cell smears obtained from 6 of 7 patients with VKH syndrome in the early stages (within 25 days). Using the silver impregnation method, these basophilic granules were strongly stained black. Moreover, they were identified as melanin by positive immunocytochemical staining. The total number of cells containing cytoplasmic granules ranged from 3 to 8 per 10,000 total cells in CSF. In contrast, no cells containing cytoplasmic granules were found in control CSF cell smears from patients with viral, bacterial, or noninflammatory diseases.

The identification of melanin-laden macrophages in the CSF of patients with VKH syndrome suggests that these cells are responsible for pleocytosis in the immunopathologic process of VKH syndrome.