Brucella abortus L7/L12 Recombinant Protein Induces Strong Th1 Response in Acute Brucellosis Patients

Background: Because of high morbidity of the brucellosis in humans and the potential use of the microorganism as an agent of biologic warfare, protection of effective vaccines and specific diagnostic reagents become necessary to eradicate brucellosis. Objective: In this study we aimed to investigate the cytokine responses and changes in peripheral blood lymphocyte subgroups of acute brucellosis patients in response to L7/L12 and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) recombinant proteins derived from Brucella abortus. Methods: levels of IFN-γ, IL-4 and IL-10 secreted from PBMCs of 25 acute brucellosis patients and 15 healthy controls, stimulated with Phytohemagglutinin (PHA), L7/L12 or GAPDH were measured by ELISA. Furthermore alterations in lymphocyte subgroups in response to these Brucella antigens were determined by flow cytometry. Results: Extracellular IFN-γ levels were found to be elevated after stimulation with L7/L12 in patients with acute brucellosis, whereas no significant changes were found in IL-4 and IL-10 levels. Similar data was also obtained with GAPDH, but the stimulation of IFN-γ production was not observed in all patients and was not as strong as that observed for L7/L12. Moreover, when the distribution of lymphocytes subgroups (CD3 + , CD3 + CD4 + , CD3 + CD8 + , CD4 + CD25 + , CD3 + CD69 + and CD3 + CD152 + ) was