Viral etiology in myasthenia gravis? Analysis of thymic tissue

Thymic cells from 26 myasthenia gravis patients were investigated by viral isolation using inoculation of supernatants obtained from thymic tissue homogenates into human and monkey cells. Living cells from 14 thymuses were also cocultivated with monkey cell lines and with human embryonic lung fibroblasts. None of the thymic biopsies showed any cytopathic effect in these cell cultures sensitive to a broad spectrum of viruses. Cytomegalovirus antigen was not detected in any of 25 biopsies investigated in an imprint immunofluorescence assay.