Phytohemagglutinin (PHA) skin test in patients with sarcoidosis

A group of 17 patients with histologically confirmed sarcoidosis were examined for the presence of anergy and the intracutaneous response to 2 mug of purified phytohemagglutinin (PHA); lymphocytes of 15 of these patients were studied for in vitro blastic response to PHA-M. Although 8 of the patients were anergic and 8 had impaired in vitro response to PHA, all patients showed a normal response to intradermal injection of PHA. It was concluded that patients with sarcoidosis have an intact intradermal response to PHA, suggesting that the anergy seen in this disease results from impaired initiation of the delayed hypersensitivity reaction and not from impaired mononuclear cell responsiveness. The PHA skin test may be a useful adjunct in the evaluation of anergic patients.