Interference in general immune function by parasite infections; African trypanosomiasis as a model system

Area of Science:

• Immunology
• Parasitology
• Cell Biology

Background:

• Parasitic infections often induce immunosuppression, ranging from specific to general immune system dysfunction.
• African trypanosomiasis exemplifies severe immune disorders, serving as a model to study parasite-induced general immune dysfunction affecting lymphoid cells.

Purpose of the Study:

• To analyze the cellular mechanisms underlying parasite-induced general immune dysfunction.
• To investigate the role of host-derived factors and macrophage activation in immunosuppression during African trypanosomiasis.

Main Methods:

• In vitro and in vivo studies using African trypanosomiasis models.
• Analysis of T-cell and B-cell subpopulations.
• Investigation of macrophage phenotype and mediator release.
• Use of trypanosome membrane fractions and antibody-coated parasites.

Main Results:

• T-cells are stimulated in vitro only with accessory cells, suggesting host-derived factors are crucial.
• Macrophages, upon uptake of antibody-coated parasites, are identified as a key target cell.
• Macrophages exhibit activation signs and mediate immunosuppression, with altered phenotype and mediator release during infection.
• Macrophage activation, induced by various means, appears to be a common pathway for general immunosuppression.

Conclusions:

• Host-derived immunosuppressive factors play a significant role in parasite-induced immune dysfunction.
• Macrophage activation is a central mechanism mediating general immunosuppression in African trypanosomiasis.
• Macrophage activation may represent a common pathway for immunosuppression across different infectious diseases.