Objective: To study the kinetics of immune response in mice and human immunized with rHB vaccine or rHBsAg derived from yeast cells (Hansenula polymorpha).
Methods: With different doses,the level of IFN-gamma secreted by spleen mononuclear cells (MNC) including CD8+ T cells by MACs of mice were detected by enzyme-linked immunospot (ELISPOT) methods after stimulation in vitro with HBsAg MHC class I peptide S28-39, respectively. At serial time points, the immunized mice were detected for IFN-gamma by ELISPOT as above and for the lymphocytotoxicity test (CTL) by specific lysis assay. The levels of IFN-gamma, IL-2, IL-5 and anti-HBs in mice induced by rHB vaccine were detected after single or three doses. Four adults were vaccinated with rHB vaccine according to 0, 1 and 2 month schedule. The peripheral blood mononuclear cells (PBMCs) were collected at the 3, 8, 21, 34 and 65 days after the first dose. The CD8+ T cells with high purity obtained by sorting from PBMCs were stimulated with rHBsAg or HBsAg peptides. The SFC of IFN-gamma, IL-2 and IL-4 of CD4+ and CD8+ T cells were determined by ELISPOT.
Results: The cytokine of IFN-gamma became detectable on day 7 and its peak value appeared on day 14 by ELISPOT. The CTL was detected on day 7 and the maximum lysis of CTL appeared on day 28. The cellular immune response of IFN-gamma of MNCs were significantly correlated with the doses vaccinated from 1 microg to 8 microg (r(positive rates) = 0.951, P(positive rates) = 0.049 < 0.05; r(SFC) = 0.996, P(SFC) = 0.000 < 0.05). IFN-gamma SFC of CD+ T cells were significantly associated with the doses from 1 microg to 4 microg (r = 0.999, P = 0.025 < 0.05). The HBsAg specific cellular immune an d humoral responses of mice immunized with three doses were significantly higher than that with a single dose (P < 0.05). The characteristics of IFN-gamma, IL-2 and IL-4 of CD4+ and CD8+ T cells were variable between individuals immunized with the same rHB vaccine. The level of IL-2 and IL-4 of responders were significantly related to the titer of anti-HBs.
Conclusion: Data from this study showed the kinesis of cellular immunity in mice and adults vaccinated with rHBsAg or rHB vaccine respectively, and the characteristics of cellular immune response in adults induced by the vaccine. Our data provided the basis of standardizing the analysis of cellular immune response to rHB vaccine.