title: Effects of inoculum size on cell-mediated and humoral immune responses of foals experimentally infected with Rhodococcus equi: a pilot study.
abstract: The objective of this pilot study was to compare the cytokine profile as well as cell-mediated and antibody responses of foals infected with a low inoculum of virulent Rhodococcus equi resulting in subclinical pneumonia to that of foals infected with a high inoculum resulting in severe clinical pneumonia. The mean (+/-SD) ratio of post-infection to pre-infection anti-R. equi IgG(T) concentration was significantly (P=0.002) higher in foals infected with the high inoculum (195+/-145; range 62-328) compared to foals infected with the low inoculum (3.9+/-4.5; range 0.5-11). Similarly, mean (+/-SD) ratio of post-infection to pre-infection IgM concentration was significantly (P=0.002) higher in foals infected with the high inoculum (12+/-4.0; range 7.4-14) compared to foals infected with the low inoculum (2.5+/-1.5; range 1.2-4.7). Proliferative responses to R. equi antigens as well as expression of mRNA for IL-2, IL-4, IL-10, and IFN-gamma in BLN were not significantly different between the two groups. There was a tendency (P=0.073) towards a higher IFN-gamma/IL-4 ratio in the low inoculum group. This study demonstrates that the size of inoculum modulates the IgG subisotype response and possibly the cytokine profile of foals.
authors.affiliation: Department Of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, United States.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Jacks
authors.forename: Steeve
authors.initials: S
authors.lastname: Giguère
mesh_terms: D000193:Actinomycetales Infections / Q000235:genetics / Q000276:immunology / Q000662:veterinary*; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D000942:Antigens, Bacterial; D001980:Bronchi / Q000276:immunology; D015169:Colony Count, Microbial; D016207:Cytokines / Q000235:genetics; D006734:Horse Diseases / Q000235:genetics / Q000276:immunology*; D006736:Horses; D007111:Immunity, Cellular; D056724:Immunity, Humoral; D007074:Immunoglobulin G / Q000097:blood / Q000145:classification; D007075:Immunoglobulin M / Q000097:blood; D008198:Lymph Nodes / Q000276:immunology; D008213:Lymphocyte Activation; D010865:Pilot Projects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016929:Rhodococcus equi / Q000276:immunology / Q000472:pathogenicity
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D016207:Cytokines; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D012333:RNA, Messenger