Published online Dec 15, 2002. doi: 10.3748/wjg.v8.i6.1098
Revised: September 2, 2001
Accepted: September 5, 2001
Published online: December 15, 2002
AIM: To prepare poly (D,L-lactide)-polyethylene glycol copolymer (PELA) microspheres loaded H.pylori lysates or Cystografin and observe their targeting in gastrointestinal mucous membrane or analyze the mucosal immune responses by oral administration.
METHODS: PELA microspheres loaded H.pylori lysates or Cystografin were prepared by double emulsion evaporation method. Their distribution in gastrointestinal mucous membrane was observed by CT.Balb/c mice orally immunized in mucosal immune responses, whose antibody production in salivary and gut washing and antibody secreting cells in Peyer’s patches (PP) were estimated by ELISA and ELISPOT, respectively. The microspheres’ physical properties, such as particle size, protein level and morphology were investigated.
RESULTS: All prepared microspheres were found to have a smooth surface morphology from 3.20-4.05 μm in diameter and high encapsulation efficiency from 74.9%-82.2%. No significant correlation in their physical properties was shown, depending on their molecular weight at the similar composition ratio. Immunization with all types of PELA-Hp microspheres elevated the saliva sIgA level at week 3 by approximately 3-4 times that with soluble antigen, which was greatly enhanced after boosting. At one week after last immunization with all types of PELA-Hp microspheres (week 8), the specific sIgA-ASCs, IgG-ASCs and sIgA in salivary rose obviously. In intestinal Peyer’s patches, the specific sIgA-ASCs were 5.92-6.98 × 104/mL cell and IgG-ASCs were 3.47-4.02 × 104/mL cell, about 5-9 times higher than those with soluble antigen (P < 0.01). ASCs in intestine were more than those in stomach and the majority of the ASCs were sIgA-ASCs. The sIgA in gut washing fluid was 1.62-1.85 OD, about 3-6 times tthat of those with soluble antigen. There were significant differences of the ASCs and sIgA in gut washing fluid as compared with those of PBS and MS-0 (P < 0.05). There appeared to be good correlation between sIgA level in gut washing fluid and sIgA-ASCs in intestinal Peyer’s patches.
CONCLUSION: PELA microspheres may be used as vehicle to delivery antigen and adjuvant in designing oral vaccination.