Ruminant Neonates: Immunological Considerations

Question 1

describe how gamma-delta T cells differ from other T cells

Answer 1

gamma-delta can utilize PRRs like TLRs, NODs, and others to recognize a broad range of antigens (peptide, protein, and nonprotein) with or WITHOUT MHC restriction

Question 2

describe how neonatal ruminants differ from other mammals in terms of their gamma-delta T cell population and recognize how this may be advantageous for their health

Answer 2

gamma-delta T cells constitute a large percentage of the lymphocyte population in blood, epithelial tissue, and inflamed sites, comprising up to 60% of PBMCs in neonates and approx 10-20% of PBMCs in adults

this is advantageous for neonates because these cells provide non-MHC-restricted cellular immunity until CD8 and CD4 T cells are established, bridging the innate/acquired human responses as frontline defenders at mucosal surfaces

Question 3

describe what is meant by the term “gut closure” as it applies to neonatal ruminants

Answer 3

FcRn receptors bind the constant region of all antibodies from the intestinal lumen, internalize them into an endosome inside the cell, and release them on the other side to the blood; these receptors are most active in neonates in the first 24 hours of life, which is why it is so important to ensure that neonatal ruminants receive adequate amounts of good quality colostrum in the first 24 hours of life to ensure transfer of passive immunity from mom to baby!!

Question 4

describe the relationship between maternal antibodies and vaccination

Answer 4

maternal antibodies protect baby until their immune system develops (hooray), but can interfere with vaccine efficacy if the levels of maternal antibodies are too high at time of vaccination, as the antibodies will just passively fight the infection instead of forcing the body to mount its own response and develop memory for future exposure