Immunological findings in a case of Cogan's syndrome.

The immune system of a case of Cogan's syndrome was investigated. A transient depression of the cell-mediated immunity was found. Thus, during the acute stage of the disease, there was a depression of the cutaneous delayed hypersensitivity reaction to PPD and a decrease in the number of T cells. There were also signs of complement consumption. A possible pathogenesis based on immune complexes due to a preceding viral infection is discussed.