Cutaneous and subcutaneous mast cell and eosinophil responses after challenge in mice vaccinated with living infective third-stage hookworm larvae

Objective To examine the quantitative and qualitative alterations in mast c ells and eosinophils distributed in the cutaneous and subcutaneous tissues of hookworm-infected, uninfected and vaccinated mice. Methods Outbred male Kunming strain mice, weighing 18 - 22 g, were vaccinat ed thrice by subcutaneous inoculation with 500 living third-stage infective larvae (L-3) of Ancylostoma caninum (A. caninum) every 2 weeks, and then c hallenged subcutaneously with 500 4 one week after the final immunization. Uninfected mice and non-immunized mice but infected with L3 served as contr ols. The abdominal skin at the site of percutaneous entry was excised from challenged mice at intervals between 6 hours and 7 days after challenge, fi xed, and then examined by light microscopy after staining with either tolui dine blue or hematoxylin and eosin. Results The total number of mast cells appearing in cutaneous, and subcutan eous tissues, and underlying abdominal musculature of immunized mice increa sed significantly compared with non-immunized mice. Mast cells from hookwor m-infected mice showed evidence of membrane rupture and degranulation in co ntrast to the intact appearance of mast cells from uninfected mice. The deg ree of mast cell degranulation was greater in vaccinated and challenged mic e when compared with non-immunized and infected mice. Similarly, eosinophil ic infiltration was greatly enhanced after 4 infection. Tissues from vaccin ated mice had a greater number of eosinophils than non-immunized mice after infection. Conclusions Mast cell alterations appearing earlier than tissue eosinophili c infiltration is major inflammatory response to Ancylostoma caninum (A, ca ninum) L-3 infection in mice. These processes are more obvious in L-3-vacci nated mice.