Experimental Research Of Biological Effect On Anti-lipopolysaccharide Fab'

The barrier function of intestinal tract always descents at different level after burned, including mechanical barrier, biological barrier and immunological barrier. There are some erosion or ulcer on the intestinal mucosa and dysbacteriosis. The level of secretory IgA(slgA)decents after the immune system function decreases. The endotoxin of the intestine often translocates from the intestine to blood circulation. It is one of the important reasons that systemic infection and multiple organ failure. At present, no special operative drugs antagonizing LPS could be applied at clinic. In recent years, it was found that there were abundant IgG sourcing from serum in egg yolk and was named IgY, which could antagonize corresponding antigens perfectly. And the IgY includes Fab' and Fc, the Fab' has the complete antibody activity, the Fc can result in allergic reaction. We hope to obtain one kind of drug which can resistant the LPS few allergic reaction rate.Using the WD antibody purification method, specific anti-LPS IgY was obtained from the egg yolk of hens immunized with LPS. With the pepsin the anti-LPS was digested to the Fab' and Fc. Then the Fc was cut to inefficient fragment. After the purification, the anti-LPS Fab' was identified.The anti-LPS Fab' was found 4.2mg/mL-egg yolk by spectrophotometer. Determined by enzyme labeling staining reaction(ELISA), the immunochemistry was 1:512 000. By SDS-PAGE and Western-blotting, the Fab' is 92% purity and its molecular weight was 44KD, it has the same immunity characteristic with the IgG of chicken serum.Then the innocuity of Fab' was certified by measuring LD₅₀ and contrasting with international six grades code, which frequently used to evaluate toxicity dimension of a compound after acute toxicity experiments in toxicology. The results showed that theLD₅₀＞7500mg/kg, and belonged to the second grade, no poison in fact. After anti-LPS Fab' had been orally administrated to Kunming-species mice, which had been made animal model of post-burned intestinal endotoxemia, the results showed that Fab' could decrease the death rate of the experimental mice significantly. Furthermore, after the therapy with IgY, Fab', the contents of LPS, DAO,TNF-a and IL-6 had decreased significantly in mice plasma, especially, the Fab' group did better than the IgY group. Pathological sections of the ileal mucous membrane showed that the same results and the significant protection action to intestinal mucosa.From the research in vivo, we could draw a conclusion that anti-LPS Fab' had the excellent effect in antagonizing LPS and prevention, treatment action to intestinal endotoxiemia.