Ml. Marin et al., DIFFERENTIAL CYTOKINE PRODUCTION IN CLONAL MACROPHAGE AND T-CELL LINES CULTURED WITH BIFIDOBACTERIA, Journal of dairy science, 80(11), 1997, pp. 2713-2720
When used in commercial fermented dairy products, bifidobacteria may e
nhance immunity by stimulating cytokine secretion by leukocytes. To as
sess whether interaction between bifidobacteria and leukocytes promote
cytokine production, we cultured RAW 264.7 cells (macrophage model) a
nd EL-4.IL-2 thymoma cells (helper T-cell model) in the presence of 14
representative strains of heat-killed bifidobacteria. In unstimulated
RAW 264.7 cells, all bifidobacteria induced pronounced increases (up
to several hundred-fold) in the production of tumor necrosis factor-al
pha compared with that of controls. Interleukin-6 production by unstim
ulated cells also increased significantly, but less than did tumor nec
rosis factor-alpha. Upon concurrent stimulation of RAW 264.7 cells wit
h lipopolysaccharide, production of tumor necrosis factor-alpha and in
terleukin-6 were both enhanced between 1.5- to 5.8-fold and 4.7- to 7.
9-fold, respectively, when cultured with 10(8) bifidobacteria/ml. In u
nstimulated EL-4.IL-2 cells, bifidobacteria had no effect on the produ
ction of interleukin-2 or interleukin-5. Upon stimulation of EL-4.IL-2
with phorbol-12-myristate-13-acetate, there were variable increases i
n interleukin-2 secretion (up to 2.4-fold for 10(6) Bifidobacterium Bf
-1/ml) and interleukin-5 secretion (up to 4.6-fold for 10(8) B. adoles
centis M101-4). The results indicated that, even when variations among
strains were considered, direct interaction of most bifidobacteria wi
th macrophages enhanced cytokine production, but the effects on cytoki
ne production by the T-cell model were less marked. Interestingly, the
4 bifidobacteria strains used commercially for dairy foods showed the
greatest capacity for cytokine stimulation. The in vitro approaches e
mployed here should be useful in future characterization of the effect
s of bifidobacteria on gastrointestinal and systemic immunity.