Effect of albendazole therapy on susceptible and resistant Haemonchus contortus larvae in Mongolian gerbils (Meriones unguiculatus) and distribution of inflammatory cells in the stomach wall

The effect of albendazole therapy on the reduction of drugsusceptible and drug-resistant strains of Haemonchus contortus larvae on day 10 post infection (p.i.), distribution and the relative numbers of innate immunity cells — eosinophils/neutrophils and mast cells in the stomach wall of immunosupressed Mongolian gerbils on days 4/1, 7/4, 10/7 and 14/11 post infection/post therapy (p.i./p.t.) were investigated in the present study. The efficacy of albendazole was significantly lower on benzimidazole (BZ) resistant larvae (L3 and L4 stages) (58.92 %) than the efficacy on susceptible strain of larvae (94.15 %). H. contortus infection elicited strong inflammation in mucosal and submucosal layers of the stomach, where mucosal mast cells MMC) were in the highest numbers in the lamina propria mucosae on day 7/4 p.i./p.t. Reduction of larval numbers following treatment resulted in a gradual decrease of MMC and connective tissue mast cells (CTMC). The lower counts of CTMC in the submucosa were seen in gerbils infected with BZ-susceptible strain during the whole period post therapy. In case of infection with BZ-resistant strain, peroxidase containig cells (eosinophils) peaked on day 7/4 p.i./p.t., whereas infection with BZ-susceptible strain elicited massive accumulation of these cells on day 4/1 p.i./p.t., particularly in the submucosa. No marked differences in eosinophils localisation were observed between both groups after the therapy. Goblet cells were found only in the proximal parts of glandulae gastricae close to the mucosal surface and no differences in the distribution in the stomach wall of both groups of animals were observed. After therapy the higher larval counts in case of BZ-resistant strain were in the correlation with the lower decline of CTMC and eosinophils, but MMC numbers were not significantly different between both treated groups. Present data indicate that in early stage post infection, the distribution of individual innate immunity cells might be directly affected by the larvae, and that the genetic and consequently biological differences related to the resistance to benzimidazoles probably had the impact on the interactions of larvae with the different immune cells in their niche.