Cellular phenotypes in Trypanosoma congolense infected sheep: the local skin reaction

Area of Science:

• Immunology
• Veterinary Parasitology
• Cell Biology

Background:

• Trypanosoma congolense infection causes local skin reactions (chancres) in sheep.
• Understanding the cellular immune response in these lesions is crucial for developing effective treatments.

Purpose of the Study:

• To characterize mononuclear cell subpopulations in ovine skin chancres caused by T. congolense.
• To investigate the kinetics of immune cell changes during primary and secondary infections.

Main Methods:

• Indirect immunoperoxidase staining using monoclonal antibodies (MoAbs) for ovine leukocyte subsets.
• Morphometric analysis of cell populations in skin lesions.
• Study of primary, treated-and-challenged, and superinfected sheep models.

Main Results:

• Significant increases in CD5, CD4, CD8, CD45R (B cells), MHC class II, and Fc receptors (FcR) on macrophages and B cells were observed from five days post-infection.
• B cells expressing MHC class II formed dense aggregates.
• Elevated CD4/CD8 ratios were noted at 5-7 days post-infection.
• Secondary and superinfections showed similar but less pronounced cellular changes compared to primary infections.

Conclusions:

• T. congolense infection induces a significant influx and activation of mononuclear cells, including B cells, T cells, and macrophages, in ovine skin lesions.
• The cellular immune response kinetics in secondary infections are comparable to primary infections.
• Superinfection leads to a milder cellular infiltration.