CELL MEDIATED IMMUNE RESPONSE AGAINST FRACTIONATED LIPOPOLYSACCHARIDE (LPS) ANTIGENS OF BRUCELLA MELITENSIS 16M IN CELL CULTURE

Abstract

Cell mediated immunity is an important part of host defence. Nitric oxide has an antimicrobial activity and play an important role against variety of bacteria including B. melitensis. This study aimed to evaluate the immunoreactivity of fractionated lipopolysaccharide (LPS) antigen of B. melitensis in cell culture. The LPS antigen was fractionated by gel filtration chromatography. The lymphoproliferation was estimated with 3-(4,5-dimethyl thiozol-2yl)-2,5 diphenyl tetrazolium bromide (MTT) colorimetric method. After comparing all the LPS antigen fractions which were fractionated by gel filtration chromatography, it was observed that LPG1 induced maximum lymphocyte proliferation in-vitro, followed by LPG2, LPG5, LPG4 and then LPG3 respectively. Nitric oxide (NO) production by the monocyte-derived macrophages on stimulation with LPS antigen of B. melitensis was assessed using a colorimetric assay for nitrite based on Griess reaction. It was observed that LPG1 produce maximum nitrite followed by LPG2, LPG3, LPG5 and LPG4 respectively. It was observed in this study that LPG-1 and LPG-2 fractions of lipopolysaccharide antigens induced maximum proliferation of lymphocytes and also induces monocytes to produce significant amount of NO. These fractionated LPS were found immunoreactive and will further be tested for the development of immunodiagnostic kit, which will be useful to detect the presence of anti-Brucella antibody in the infected host