[The study on the immunomodulating effect of marine protein peptides in mice].
OBJECTIVE
To observe the effects of marine protein peptide (MPP) on immunomodulating in mice and its possible mechanism.


METHODS
Female ICR mice (6-8 weeks old) were administered the MPP for 4 weeks with the dose of 0.22 g/kgBW, 0.45 g/kgBW and 1.35 g/kgBW. Spleen and thymus were weighted and cell-mediated immune functions, humoral immune functions, phagocytic functions of mononuclear phagocyte, NK cell activity assays, the T cell subpopulation of the spleen tissue by the flow cytometer and the concentrations of cytokines in serum by cytometric bead array were examined.


RESULTS
The capacity of lymphocyte proliferation induced by Con A (0.33 +/- 0.21), DTH response (0.36 +/- 0.11) mm in MPP 0.22 g/kgBW group were significantly increased in comparison with these values in control group (0.15 +/- 0.10) and (0.21 +/- 0.10)mm, respectively, P < 0.05. IgM-PFC number of MPP 0.22 g/kgBW group (1.64 +/- 0.06), 0.45 g/kgBW group (1.59 +/- 0.05) and 1.35 g/kgBW group (1.56 +/- 0.10) were higher than those in control group (1.38 +/- 0.10), P < 0.01; and the level of serum HC50 of MPP 0.22 g/kgBW group (141.00 +/- 23.00) and 0.45 g/kgBW group (130.40 +/- 33.20) were greater than the control (100.30 +/- 19.40) , P < 0.01. The activity of NK cells in MPP 0.22 g/kgBW group (1.672 +/- 0.142) was significantly elevated in comparison with this value in control group (1.392 +/- 0.182), P < 0.05. The percentage of CD4 T helper (Th) cell in spleen of MPP 0.22 g/kgBW group (32.84 +/- 3.776)% and 0.45 g/kgBW group (32.42 +/- 3.507) % was higher than those in control group (25.06 +/- 0.354) %, P < 0.05. The concentrations of IL-2 in serum of MPP 0.22 g/kgBW group 181.06 pg/ml, 0.45 g/kgBW group 94.84 pg/ml and 1.35 g/kgBW group 102.61 pg/ml were higher than those in control group 0.50 pg/ml, P < 0.05; and the level of IL-5 of MPP 0.22 g/kgBW group (38.31) pg/ml was greater than the control 0.50 pg/ml, P < 0.05. Nevertheless, no obvious effects on weight increasing, the ratio of immune organ and body weight and phagocytosis capacity were observed in our study.


CONCLUSIONS
MPP could improve the immune functions in mice, and might be by the mechanism of enhancing the function of Th cells stimulating the secretion of Th1 and Th2 type cell cytokines.
Zhang
Zhao-feng
ZF
Department of Nutrition and Food Hygiene, School of Public Health, Peking University, Beijing 100083, China.
Pei
Xin-rong
XR
Han
Xiao-long
XL
Wang
Jun-bo
JB
Long
Zhu
Z
Shen
Xiao-yi
XY
Li
Yong
Y