Effects of lamivudine on the hepatitis B virus specific CD8+ cytotoxic T lymphocyte responses via peptide-MHC tetrameric complexes assay

Lamivudine, an oral nucleoside analogue, inhibitshepatitis B virus (HBV) replication. It has been shown tobe able to restore T cell responsiveness and to induce atype 1 T helper cell (Th 1) immunity in chronic HBVpatients. To further examine the effects of lamivudineon cytotoxic T lmphocyte (CTL) responses, two HBVantigenic peptide-HLA-A2 tetrameric complexes containingpeptides derived from HBV core protein (residues 18-27;FLPSDFFPSV) and polymerase (residue 551-559; YMDDVVLGA)were constructed. These two tetramers were used toserially determine the frequency of HBV antigen-specificCD8⁺ T cells before and during the treatment oflamivudine. The specificity of these tetramers wasconfirmed by (a) nonstaining of CD8⁺ T cells fromHLA-A2-negative HBV patients, (b) having variablefrequency data in the different teteramer measurement,and (c) showing peptide-specific CTL activity in thesorted tetramer-stanining CD8⁺T cells. Lowfrequency of HBV-specific CTLs was measured for bothtetramers before lamivudine treatment. However, thenumber of CD8⁺ T cells specific for HBV core 18-27increased significantly during lamivudine treatment. Incontrast, relatively lower frequency of HBV pol 551-559specific CD8⁺ T cells was persistently measuredafter lamivudine treatment. These results indicated thatthe lamivudine treatment could enhance HBV specific CTLresponses.