Induction of antibody and T-cell responses by immunization with ISCOMS containing the 38-kilodalton protein of Mycobacterium tuberculosis

In this study, we investigated the influence of different amounts of N-(pal mitoyloxy) succinimide (PA-NNS): attachment of lipid tails to the protein a nd Quil A on the immunogenicity of the 38-kDa mycobacterial protein incorpo rated into immunostimulating complexes (ISCOMS; 38-kDa ISCOMS). The additio n of higher amounts of Quil A during the ISCOMS preparation increased the a mount of protein incorporated into ISCOMS, whereas the use of higher amount s of PA did not influence this parameter. Low antibody responses were obser ved after primary immunization with all 38-kDa ISCOMS preparations which, h owever, strongly increased after booster injections. IgG2a is the major sub class IgG induced by these ISCOMS preparations. There were only slight diff erences between the various ISCOMS formulations in their capacity to induce cytotoxic T-lymphocytes (CTLs). Spleen cells primed with ISCOMS prepared w ith the highest amount of Quil A produced high levels of IFN-gamma after st imulation with T helper cell type one (Th1) peptide of the 38-kDa protein ( aa 70-84), 38-kDa protein or purified protein derivate (PPD). Spleen cells primed with ISCOMS prepared with the lowest amount of Quil A only substanti al IFN-gamma levels were detected after stimulation with 38-kDa protein. IL -4 secretion was very low or not detectable with all ISCOM preparations. Th ese results therefore demonstrated that all 38 kDa-ISCOMS preparations were : (1) immunogenic by inducing antibodies, Th1 and CTL responses: (2) that t he way in which the ISCOMS were prepared, e.g. the amount of Quil A used, m odulates the epitope specificity of the Th1 response. (C)2000 Published by Elsevier Science Ltd.