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Yap and Ng
after feedingwith lentinan but returned to baseline after 24 hr (Fig. 3a–d). The
IL-1a (Fig. 3a) and IL-2 (Fig. 3b) peaked at 2 hr postfeeding with lentinan.
Both the TNF-a and IFN-g peaked at 4 hr postfeeding(Fig. 3c and 3d).
These results suggested that oral administration of lentinan may serve as
a means of activatingthe immune system, provokingthe immune responses
required for disease prevention. Lentinan, once ingested, may encounter the
gut-associated lymphoid tissue (GALT), which is a well-developed immune
network, evolved to protect the host from infectingpathogens. Lentinan may
also be absorbed into the systemic circulation, thereafter, involved in inducing
immune systems against future pathogenic attack. Quantitative analysis of
orally administered lentinan in murine blood carried out usinglimulus
colorimetric test demonstrated that pure lentinan was detected in the murine
blood and peaked at 0.2 mg(equivalent to the usual intravenous or intraperitoneal
inoculation dosage) 30 min after feeding (Yap and Ng, unpublished
data).
When fed with crude mushroom homogenates, IL-1a, IL-2, and TNF-a
levels were also induced but to much lower levels when compared to lentinanfed
cohort. The IFN-g level was not significantly induced. The lipid and
protein fractions from the mushrooms did not result in noticeable induction
of any of the four cytokines tested and was at the baseline like the buffer-fed
cohort (control).
Many interestingbiological activities of lentinan have been reported.
This included an increase in the activation of nonspecific inflammatory
responses such as APP (acute-phase protein) production (87), vascular
dilation, and hemorrhagic necrosis of the tumors (88). Bradykinin-induced
skin reaction could be used as an index of vascular reactions against lentinan
and this skin reaction could be used to moniter the host sensitivity to lentinan
in antitumor responses (89).
Activation and generation of helper and cytotoxic T cells (10,67,79,90–
93) is an essential aspect of lentinan treatment. The augmentation of immune
mediators such as IL-1 and IL-3, colony-stimulatingfactor(s) (94), migration
inhibitory factor (32,94,95), and increasingthe capacity of PBM (peripheral
blood mononuclear) cells (52,53) contributed additively to the antitumor
efficacy. Wangand Lin (96) postulated that the immunomodulatingeffect of
lentinan might be relevant to change of T-cell subpopulation and increase of
TNF production.
The recent study of Yap and Ngconfirmed that T-lymphocytes were
increased significantly (fourfold, p < 0.001, Student’s t-test) after feeding
with lentinan (Table 2). The CD3, CD4 (T-helper), and CD8 (T-cytotoxic)
lymphocytes were isolated usingT-cell-enrichment columns. All three types
of CD lymphocytes were activated in comparison with the buffer-fed controls.
It was noted that the placebo (controls) effects did result in some degree of