[Effects of Bacillus Calmette-Guerin vaccination on immune functional development of splenic T cell in neonatal mice].

OBJECTIVE

Almost every neonate receives Bacillus Calmette-Guerin (BCG) vaccination in China. The authors' previous study showed that BCG promoted cord blood monocyte-derived dendritic cells maturation and induced high level of interleukin (IL)-10, medium level of interferon (IFN)-gamma, but low level of IL-4 production by cord naive T cells. The experiments in the present study were designed to explore the effects of neonatal BCG vaccination on immune functional development of splenic T cells in mice in vivo.

METHODS

Neonatal BALB/c mice were inoculated with BCG intraperiotoneally. Four weeks later, spleen cells of mice were isolated and surface molecular markers of CD4, CD25 and CD44 and intracellular IFN-gamma, IL-10, and IL-4 in CD3(+) T cells were detected by flow cytometry. Furthermore, mRNA expression of transcription factor T-bet, Foxp3 and GATA-3 were analyzed by RT-PCR.

RESULTS

The percentage of total CD4(+) T cells decreased [(23.50 +/- 2.59)% vs. (47.38 +/- 10.41)%, P < 0.01] but the percentage of CD25(+) [(24.92 +/- 2.74)% vs. (20.27 +/- 2.85)%, P < 0.05] and CD44(+) [(89.29 +/- 2.56)% vs. (82.98 +/- 5.51)%, P < 0.05] T cells in CD4(+) T cells was higher in BCG-vaccinated mice than that in controls. Meanwhile, the percentage of IFN-gamma positive [(6.52 +/- 2.40)% vs. (3.13 +/- 2.03)%, P < 0.05] and IL-10 positive [(14.81 +/- 3.65)% vs. (10.90 +/- 1.61)%, P < 0.05] but not IL-4 positive [(1.17 +/- 0.46)% vs (1.51 +/- 0.75)%, P > 0.05] cells in CD3(+) T cells of BCG-vaccinated mice was significantly higher than that of non-BCG-vaccinated mice. In comparison with BCG-naive mice, T-bet was significantly high in BCG-vaccinated mice [T-bet/beta-actin 0.44 +/- 0.11 vs. 0.28 +/- 0.06, P < 0.05], but there was no significant difference in GATA-3 [GATA-3/beta-actin 0.46 +/- 0.08 vs. 0.50 +/- 0.10,P > 0.05] and Foxp3 [Foxp3/beta-actin vs. 0.27 +/- 0.11 and 0.30 +/- 0.16, P > 0.05] mRNA expression between the two groups.

CONCLUSION

Neonatal BCG vaccination could induce strong Th1 but weak Th2 response as reported previously. Though neonatal BCG vaccination was not capable of inducing CD4(+)CD25(+) regulatory T cell response with Foxp3 expression, it caused increase of IL-10(+) CD3(+) cells which might represent some regulatory T cells producing IL-10.