Parasitic organisms like Toxoplasma, Schistosoma, and Trypanosoma pose challenges to the immune system through their complex life cycles that involve changing antigens and locations over time. The most effective immune response depends on factors like the type of parasite, site of infection, and current life cycle stage, and involves both antibody and cell-mediated responses, including IgE, CD4 T cells, and recruitment of eosinophils, neutrophils, and other immune cells through various chemokines and cytokines.

3. Toxoplasma
Schistosoma
Trypanosoma
One of the biggest
challenges posed to the
immune response by
most parasites is their
complicated life cycle,
leading to changes in
antigenic structure and
location over time.
Therefore,
the most effective
immune response will
depend on the type of
organism, the location of
the
infection, and the life
cycle stage of the
parasite.

16. The response includes an IgE humoral
component (top) and a cell-mediated
component involving CD4 T cells
(bottom).
C = complement;
ECF = eosinophil chemotactic factor;
NCF = neutrophil chemotactic factor;
PAF = platelet-activating factor.