Dynamic changes in circulating and antigen-responsive T-cell subpopulations post-Mycobacterium bovis infection in cattle.
Bovine tuberculosis is a threat to animal and human health in several countries. Greater understanding of the immunology of the disease is required to develop improved tests and vaccines. This study has used a model of bovine tuberculosis, established in the natural host, to investigate the dynamic changes that occur in the circulating T-cell subpopulations after infection. When the phenotypic composition of the peripheral blood lymphocytes was determined pre- and post-experimental infection, the response to disease comprised three phases. Firstly, the WC1/gamma delta T cells decreased and then increased, suggesting localization to developing lesions and clonal expansion. Secondly, the CD4:CD8 ratio increased. Thirdly, the CD4:CD8 ratio decreased to less than pre-infection measurements. The latter changes suggested sequential involvement of CD4 and then CD8 T cells. The proportion of cells expressing interleukin-2 receptor (IL-2R) also increased. Panels of T-cell clones were established at various stages post-infection and all clones that exhibited antigen responsiveness were phenotyped. T-cell clones from early infection were WC1/gamma delta and CD4 in phenotype, while CD8 clones appeared later in infection, eventually becoming dominant. Therefore, from in vivo and in vitro evidence, it was suggested that there is a dynamic progression in the T-cell subpopulations involved dominantly in responses to mycobacteria.
Pollock
J M
JM
Veterinary Sciences Division, Department of Agriculture for Northern Ireland, Stormont, Belfast.
Pollock
D A
DA
Campbell
D G
DG
Girvin
R M
RM
Crockard
A D
AD
Neill
S D
SD
Mackie
D P
DP
D000818:Animals; D016516:CD4-CD8 Ratio; D002417:Cattle; D002999:Clone Cells / Q000276:immunology; D005434:Flow Cytometry; D016130:Immunophenotyping; D007700:Kinetics; D008213:Lymphocyte Activation / Q000276:immunology; D008297:Male; D008562:Membrane Glycoproteins / Q000032:analysis; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000032:analysis; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D014380:Tuberculosis, Bovine / Q000276:immunology*
C086500:DMBT1 protein, Bos taurus; D008562:Membrane Glycoproteins; D016692:Receptors, Antigen, T-Cell, gamma-delta