Short communication: Lymphocyte proliferative responses in cattle naturally infected with digital dermatitis consists of CD8+ and gamma delta T cells but lack CD4+ T cells

Authors: Wilson-Welder, Jennifer; Nally, Jarlath; Alt, David; Humphrey, Samuel; Olsen, Steven

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/2/2018
Publication Date: 6/13/2018
Citation: Wilson-Welder, J.H., Nally, J.E., Alt, D.P., Humphrey, S.B., Olsen, S.C. 2018. Short communication: Lymphocyte proliferative responses in cattle naturally infected with digital dermatitis consists of CD8plus and gamma delta T cells but lack CD4plus T cells. Journal of Dairy Science. 101(9):8301-8307. https://doi.org/10.3168/jds.2017-13913.
DOI: https://doi.org/10.3168/jds.2017-13913

Interpretive Summary: Digital dermatitis (DD) is a leading cause of lameness in cattle. Observations suggest that lesions reoccur on the same and on new feet, indicating failure of immunological memory. To determine if immune responses are generated, cellular reactivity was evaluated in cattle with DD. Animals with recent lesions had increased antibody, and reactive B cells, and gamma-delta T cells to Treponema, a dominant type of bacteria found in DD. They did not have reactive CD4 cells that are usually associated with memory-type immune responses. Failure to generate immunological memory could explain the reoccurrence of DD in the same animal.

Technical Abstract: Digital dermatitis is an infectious hoof disease of cattle and the leading cause of lameness. This disease is complicated by the reoccurrence of the lesions and the observation of lesions on more than one limb at different time-points indicating there may be failure to develop adequate immune response. The objective of this study was to characterize the peripheral blood cellular response in naturally infected and naïve cattle to bacterial antigens derived from digital dermatitis lesions. Peripheral blood mononuclear cells were isolated from dairy cattle identified as having active or chronic lesions during routine hoof-trimming 4 weeks prior to blood collection. Following bacterial antigen stimulation, cells were analyzed for proliferation and phenotype by flow cytometry, and culture supernatants analyzed for IFN-gamma secretion. Digital dermatitis infected animals had greater serum antibody titers to Treponemal antigens, higher percentage of proliferating gamma delta-T cells and B cells, and increased IFN-gamma secretion in vitro when compared to responses of naïve animals. No increase in proliferation of CD4+ or CD8+ T cells was detected. Our data suggests that proliferative responses of gamma delta-T cells and B cells may have been non-specific and T cell independent. The lack of responsiveness of CD4+ or CD8+ memory cells could explain the high rate of reoccurrence of digital dermatitis in infected animals.