Abstract: Objective To investigate the effects of intragastric administration of human interferon-α (hIFN-α)-transformed
Bifidobacterium on immune functions of mice. Methods The E.coli-Bifidobacterium shuttle expression vector containing hIFN-α
gene was constructed and transformed into Bifidobacterium. The hIFN-α-transformed Bifidobacterium suspension (1010 /ml) was
prepared after induction with 0.2% L-arabinose for hIFN-α expression and administered intragastrically in male Balb/C mice
at the dose of 0.1 ml every other day for 2 weeks, with the mice receiving empty vector-transformed Bifidobacteria as the
negative control and those having an equal volume of saline as the blank control. The percentages of mononuclear cell subsets
in the thymus, spleen and blood were detected in the mice by flow cytometry, and the serum levels of IL-4, IL-12, IFN-γ and
TNF-α were assayed using mouse cytokine FlowCytomix Kit. Results The percentages of CD3+CD8+ and CD4+CD8+ cells in the
thymus, CD3+CD4+, CD3+CD8+ and CD4+CD8+ cells in the spleen, and CD3+CD8+ cells in the blood all increased significantly in
IFN group as compared with those in the negative and blank control groups (P<0.01 or 0.05). The serum level of IFN-γ also
increased significantly (P<0.05) while IL-4 level remained unchanged in IFN group compared with those in the two groups.
Conclusion Intragastric administration of hIFN-α-transformed Bifidobacterium promotes lymphocyte proliferation and
maturation and increases the serum levels of Th1 cytokines in mice.