31 SummaryWe studied experimental lagochilascariosis in male and female mice of four strains. The survival ratio and number of larvae recovered varied: B10.A and C57BL/6 mice had the highest number of larvae 90 days after infection and the lowest survival ratio at 345 days of infection. BALB/c mice had an intermediate survival ratio and number of larvae. A/J mice had the lowest number of larvae and the highest survival ratio. Our findings suggest that resistance to Lagochilascaris minor is not linked to the H-2 a region because both susceptible B10.A and resistant A/J mice express the H-2 a haplotype. However, the pattern of mortality and larvae recovered that we observed in C57BL/6 mice, which possess the same genetic background as B10.A, indicates that the background genotype does affect the outcome of lagochilascariosis in mice. This study demonstrates that the genetic background, but not H-2 a or sex, determine the outcome of lagochilascariosis in mice.

Lagochilascaris minor is the causative agent of lagochilascariosis, a disease that affects the neck region causing exudative abscesses with eggs, adult parasites and L3/L4 larvae within purulent exudates. Nowadays, mice are considered intermediate hosts for the parasite. To determine the pattern of infection in B1 cell-defective mice, experimental lagochilascariosis was studied in BALB/c and X-chromosome-linked immunodeficient (Xid) mice. BALB.xid infected mice showed higher survival ratios and less intense lung lesions than BALB/c mice. Serum levels of IL-10 was higher in BALB/c infected mice when compared to BALB.xid animals; however, serum levels of IFNγ, in control and infected BALB.xid mice, were statistically different from that seen in BALB/c mice. We discuss the participation of B1 cells and their cytokines in the resistance to infection.

SummaryLagochilascaris minor is the causative agent of human lagochilascariosis, a disease that affects the neck region causing abscesses with eggs, adult parasites and L3/L4 larvae within purulent exudates. Nowadays, mice are considered intermediary hosts for the parasite. In previous study we observed that A/J mice experimentally infected with Lagochilascaris minor showed higher survival ratios than B10.A mice. Now, we denoted that A/J mice (resistant to experimental infection) produced higher levels of IgM, IgG and IgA against the crude extract (excepted for IgM) and secreted/excreted antigens of the parasite; on the other hand, B10.A mice (susceptible to experimental infection) produced higher levels of IgE in the later period of the experimental infection than A/J infected mice.