Lymphocyte transformation test in fixed drug eruption.

Twenty-one patients with fixed drug eruption were studied with the lymphocyte transformation test. In no patient was there blast transformation when the responsible drug (1:10,000 dilution) was added to the lymphocyte culture. The addition to the lymphocyte culture of 0.4 ml of autologous serum, taken at the acme of the clinical reaction, produced blast transformation of the lymphocytes, and when the responsible drug (1:10,000 dilution) was added to this system, blast transformation increased by several times. The addition of the responsible drug to autologous serum obtained during clinical remission produced a minimal or negative response. These findings suggest that during fixed drug eruptions a blast transforming factor appears temporarily in the serum and increases its activity in the presence of the responsible drug. This factor spontaneously diminishes or disappears a few days after clinical exacerbation.