[Influence of nanoparticle-encapsulated SEA on T-cell subgroups and its antitumor effect on hepatoma]

Staphylococcal enterotoxin A (SEA) is one of the widely researched superantigens, which is prospective in antitumor therapy. However, its application is limited due to the toxicity. This study was conducted to prepare the nanoparticle-encapsulated SEA (NSEA) and to observe its influences on the T-cell subgroups and the antitumor effects in vivo.

NSEA was prepared by the interfacial polymerization method.BALB/c mice were divided into 3 groups (each group had 12 mice). After injection of 0.1 ml normal saline (NS I group), 0.1 ml 2 mg/L free SEA (SEA I group) and 0.1 ml 2 mg/L NSEA(NSEA I group), the changes of T-cell subgroups (CD4(+) and CD8(+)) were observed. The mice model bearing hepatocellular carcinoma H22 were injected with 0.1 ml NS(NS II group), 0.1 ml 2 mg/L free SEA(SEA II group), 0.1 ml 2 mg/L NSEA (NESA II group), then the tumor volume and the survival time were recorded.

SEA and NSEA significantly improved the absolute number of CD4(+) and CD8(+) T cells (P< 0.01); while the proportion of CD4(+) to CD8(+) did not change (P >0.05). The numbers of CD4(+) and CD8(+) T cells in NSEA I group reached the peaks [(8.26+/-1.46) x 10(9)/L and (5.53+/-0.91) x 10(9)/L] at 72 hours. The absolute number of CD4(+) T cells in SEA I group reached the peak of (8.61+/-1.59) x 10(9)/L at 48 hours,and the absolute number of CD8(+) T cells reached the peak of (6.05+/-1.31) x 10(9)/L at 72 hours; both of them descended to normal level at 96 hours. The inhibition rates of SEA II group and NSEA II group were 58.9% and 50% and the percentages of life span increase were 167% and 169%, respectively.

NSEA and SEA could induce the activation and proliferation of T cells in vivo but could not influence the proportion of CD4(+) and CD8(+) cells in the mice. The effects of NSEA were weaker but longer than that of SEA. This study demonstrated that NSEA has the sustained release effects and prolongs the effective time.