Cord blood lymphocyte transformation responses to Legionella pneumophila.

Cord blood lymphocytes were obtained from 94 neonates for transformation assays with sonicated and partially Legionella antigens and phytohemagglutinin. The Legionella antigens gave mean stimulation indices (SI) of approximately three times the background. The nonspecific mitogen phytohemagglutinin gave mean SI of 23 times the background. There was some minor nonspecific stimulation of cord blood lymphocytes by Legionella antigens but not enough to account for the SI seen in patients with Legionnaires' disease (48 +/- 14).