Differentiation and Regulation of Bovine Th2 Cells In Vitro.

Area of Science:

• Immunology
• Veterinary Medicine
• Cell Biology

Background:

• Bovine Th2 cells are typically identified by Interleukin-4 (IL4) mRNA expression.
• The correlation between IL4 transcription and protein expression in bovine Th2 cells remains unclear.
• Previous studies suggest low frequencies of IL4-expressing Th2 cells in cattle.

Purpose of the Study:

• To investigate the protein expression of IL4 in bovine CD4+ T cells across different tissues.
• To determine the capacity of bovine CD4+ T cells to differentiate into Th2 cells in vitro.
• To explore the regulatory mechanisms of IL4 expression and Th2 differentiation in cattle.

Main Methods:

• Flow cytometry was used to analyze IL4+ CD4+ T cells in blood, spleen, and lymph nodes.
• In vitro Th2 differentiation assays were performed using naïve bovine CD4+ T cells stimulated with anti-bovine CD3 and a Th2 differentiation kit.
• Quantitative PCR, unbiased proteomics, and manipulation of T cell receptor stimulation strength were employed to assess differentiation and IL4 expression.

Main Results:

• Limited IL4 protein was detected in CD4+ T cells across examined bovine tissues.
• In vitro differentiation primarily yielded IFNγ-producing cells, with less than 10% co-expressing IL4.
• GATA3 expression was reduced post-differentiation, and external pathogens like *Ostertagia ostertagi* extract inhibited key signaling pathways.

Conclusions:

• Bovine CD4+ T cells can respond to Th2 differentiation stimuli, but IL4 protein expression is not a reliable marker.
• The IL4 pathway regulation in bovines differs significantly from that observed in mice and humans.
• External factors, such as parasitic infections, can modulate bovine Th2 cell differentiation.