Heat labile enterotoxin of Escherichia coli enhances intestinal cellular immune response to newcastle disease vaccine when administered by intranasal route

Heat labile (LT) enterotoxin of Escherichia coli has been shown to have potent mucosal adjuvant activity in laboratory animals. In the present study, the intestinal immune response to Newcastle disease vaccine ‘F’ strain (NDF) was evaluated with the co-administration of LT. The proliferative responses of intraepithelial lymphocytes (IELs) were significantly higher in birds vaccinated with LT adjuvanted NDF vaccine. In vitro non-specific cytotoxic activity of IELs was also higher in chicks receiving LT adjuvanted vaccine. The results of this study indicate adjuvant activity of LT in the induction of intestinal immune response in chicken.