Trichinella spiralis reinfection: changes in cellular and humoral immune response in BALB/c mice

Trichinella spiralis infection induces a host cell-mediated and humoral response. The role of T and B lymphocytes in the immune response of mice reinfected with 2 × 400 T. spiralis larvae was studied in relation to the parasite burden. BALB/c mice were infected on days 0 and 60 and immunological parameters were examined within a period of 180 days. In comparison with a single T. spiralis infection, T- and B-lymphocytes in reinfected mice responded by a significant increase in the proliferative activity during 10 days after reinfection. At the same time, the percentages of CD4+ T-cells of reinfected mice were also increased. In contrast, the CD8+ T-cell numbers were significantly reduced almost 30 days after reinfection. High concentration of serum IFN-γ lasted till the end of the experiment. The IL-5 level was increased only for 2 weeks after reinfection, followed by its decrease. Kinetics of specific anti-Trichinella immunoglobulins IgG2a was not affected with reinfection, but specific antibodies IgG1 significantly increased after reinfection and persisted elevated till the end of the experiment. Lower numbers of adults (69.2 % reduction) in the small intestine and 72.3 % reduction in muscle larvae were found after reinfection. Stimulation of the host immune response — the increased activity of CD4+ T lymphocytes and high levels of IFN-γ and specific IgG1 after reinfection, contributed to the reduction of the parasite burden.