Abstract:
Among the most common probiotics (PB) are the lactic acid bacteria (LAB) which have been known to have beneficial effects on health including the stimulation of certain cells of the immune system. This study used colorimetric methods to examine the effect of viable and heat-killed preparations of two LAB species isolated from Filipino fermented foods, Lactobacillus fermentum (4B1) and Lactobacillus pentosus (3G3), on murine peritoneal macrophage activation through nitric oxide (NO) production and proliferation of splenic T-cells in vitro. A PB found in commercial fermented probiotic drink, Lactobacillus casei (IY9), was used as reference strain. NO was detected colorimetrically by measuring nitrite (NO?), a stable breakdown product of NO that reacts with A'-l-napthylethylenediamine dihydrochloride (NED) and yields a red-violet diazo dye. T-cell proliferation was determined by measuring the absorbance of a colored formazan product, an MTS tetrazolium compound bioreduced by NADPH or NADH of metabolically active cells. Results show that only viable 4B1 induced NO production in murine macrophages. Only viable 4B1, having a NO? concentration of 39.44 ± 23.88 pM, was found to be statistically similar to the positive control LPS which registered a NO? concentration of 49.52 ± 6.09 pM. On the other hand, neither preparations of 3G3 showed considerable effects on murine NO production. The NO2 concentration produced by IY9 was only 19.03 ± 7.48 pM, lower that of viable 4B1. On the other hand, viable 3G3 induced the greatest T-cell proliferation with 0.156 ± 0.099 absorbance, followed by 4B1 and IY9. However, the T-cell proliferative properties of the treatments were not comparable statistically to the positive control Con A with an absorbance reading of 0.344 ± 0.056. This may be due to insufficient PB concentration administered; the elimination of accessory cells in the T-cell extraction; or the possible anti-mitogenic effect of the PB used in this study.
