Immunomodulatory effect of a plasmid expressing CD40 ligand on DNA vaccination against human immunodeficiency virus type-1

CD40 ligand is a costimulatory molecule which acts a potent immunomodulator . We found the mice inoculated with human CD40 ligand expression plasmid (p MEhCD40L) combined with human immunodeficiency virus type-1 (HIV-1) DNA vac cine exhibited both humoral and cellular antigen-specific immunological enh ancement. The expression of hCD40L induced predominantly antigen-specific i mmunoglobulin G (IgG) antibody response while it failed to induce mucosal I gA response. Delayed-type hypersensitivity (DTH) and cytotoxic T lymphocyte (CTL) activity were induced in a dose-dependent manner. Examination of the relative levels of the two IgG subclasses showed that co-injection of pMEh CD40L enhanced IgG2a response without suppressing IgG1 response. Similarly, the expression of pMEhCD40L enhanced not only T helper 1 (Th1)- but also T h2-type cytokine production. In conclusion, co-inoculation of pMEhCD40L wit h DNA vaccine was shown to be a useful way to enhance CTL responses without suppressing the humoral immune response in acquired immune deficiency synd rome (AIDS) patients.