Adjuvant materials that enhance bovine γδ T cell responses

Abstract

Despite the availability of vaccines and antibiotics, viral, bacterial and parasite-induced intestinal and pulmonary diseases still cause significant losses to the livestock industry. Excepting improvements in calf survival due to predation, there have been only modest improvements in bovine calf survival since 1991. Strikingly, digestive and respiratory diseases still account for almost half of the non-predator deaths in calves. The innate immune system has evolved to rapidly recognize and respond to invasive microbial threats. Augmentation of innate immunity is a broad-spectrum, potent and non-specific alternative approach to effectively counter a microbial invasion. In recent years we have focused our research efforts on the development of effective and inexpensive adjuvant therapies for cattle that can be used to help mitigate infection. Unique in our approach to the development of the potential new treatments, is our focus on bovine γδ T cells, which are important lymphocytes of the innate immune system and of particular importance to ruminant immunological health. This review focuses on recent results obtained using two such adjuvant materials.

Harnessing γδ T Cells as Natural Immune Modulators

“…When cytokine expression in mesenteric lymph nodes (MLNs) and spleen cells were measured, the feeding of açai polysaccharides induced expression of IL-12 in supernatant fluids from cultured MLN and spleen cells from the treated mice. IL-12 was also detected in the serum of the mice [127]. Expression of IFNγ was also increased in spleen cells from açai polysaccharide-fed mice, similar to the previous finding using nasal administration [125].…”

“…The role of the β-glucan receptor dectin-1 was particularly investigated, since IL-12 is produced by immune cells following ingestion of β-glucans [128]. Our result demonstrated that açai polysaccharides contain appropriate linkages for recognition by dectin-1 using an inhibition ELISA against β-glucan [127]. Furthermore, açai polysaccharides specifically block binding of anti-dectin-1 antibodies to immune cells in a flow cytometry based assay.…”

“…No adverse effects were noted in the açaitreated mice. In a model of chemically induced colitis, mice that were fed açai had a reduced deleterious inflammatory response in the gut [127]. Considering that there are no adverse effects following açai ingestion, this polysaccharide could represent a safe and novel approach to stimulating γδ T cells and other innate cells, potentially to promote their innate protective and homeostatic functions at the mucosal surface.…”

Transcriptome analysis of immune genes in peripheral blood mononuclear cells of young foals and adult horses

“…Knowledge about γδ T cell populations in the horse is scarce. Studies in other species have established that γδ T cells are innate immune cells with antigen-presenting and cytolytic functions [92]. A transient increase in the γδ T cell population occurs in calves over the first 2 months, perhaps similar to that suggested by the equine transcriptome dataset presented here; overall γδ T cells comprise approximately 40% of calf PBMCs at birth and then decline to adult cow levels (approximately 15%) by 5 months of age [93].…”

Amphotericin B, an Anti-Fungal Medication, Directly Increases the Cytotoxicity of NK Cells

“…A dose of 1 mg/L AMP-B corresponds to approximately 1.08 µM, which is sufficient to increase the cytotoxicity of NK cells according to our current study. AMP-B is also suggested as an adjuvant molecule for murine and bovine γδ T cell responses [16]. In this report, AMP-B injection into mice increased IFN-γ production, which could be produced by NK cells and T cells.…”