Antigen-specific and nonspecific interferon response of peripheral blood leukocytes from patients with chronic brucellosis.

Thirty seven blood samples from 21 patients with chronic brucellosis were studied for interferon response to Brucella specific antigens and to the classical IFN inducers. Whole blood technique for IFN induction and bioassay with A549 cells challenged with EMC virus for IFN detection were used. Two different antigen preparations (BRU-1 and BRU-2) used for the serologic diagnosis of brucellosis, stimulated significantly (P less than 0.001) the synthesis of IFN-alpha and IFN-gamma in the whole blood cultures from the patients with chronic brucellosis but not from the control subjects. The detoxified antigen (brucellin) was inactive as the IFN inducer. BRU-1 and BRU-2 antigens induced also low levels of IFN-alpha + IFN-gamma in the short term cultures of the separated peripheral blood leukocytes (5-10 X 10(6) cells/ml) from healthy blood donors. This resembled stimulation of the leukocytes with LPS. Brucellin was inactive in the leukocyte culture. Despite the chronic infection lasting many years the brucellosis patients had apparently intact IFN system because the response of their leukocytes to NDV, PHA + PMA or LPS was not significantly different from that of the healthy blood donors. The importance of the relative balance of the IFN system for the pathogenesis of brucellosis is suggested and contrasted with IFN disfunction in the acquired immune deficiency syndrome.