Isolation of Mycobacterium avium subspecies paratuberculosis reactive CD4 T cells from intestinal biopsies of Crohn's disease patients.
BACKGROUND
Crohn's disease (CD) is a chronic granulomatous inflammation of the intestine. The etiology is unknown, but an excessive immune response to bacteria in genetically susceptible individuals is probably involved. The response is characterized by a strong Th1/Th17 response, but the relative importance of the various bacteria is not known.


RESULTS
In an attempt to address this issue, we made T-cell lines from intestinal biopsies of patients with CD (n = 11), ulcerative colitis (UC) (n = 13) and controls (n = 10). The T-cell lines were tested for responses to various bacteria. A majority of the CD patients with active disease had a dominant response to Mycobacterium avium subspecies paratuberculosis (MAP). The T cells from CD patients also showed higher proliferation in response to MAP compared to UC patients (p<0.025). MAP reactive CD4 T-cell clones (n = 28) were isolated from four CD patients. The T-cell clones produced IL-17 and/or IFN-gamma, while minimal amounts of IL-4 were detected. To further characterize the specificity, the responses to antigen preparations from different mycobacterial species were tested. One T-cell clone responded only to MAP and the very closely related M. avium subspecies avium (MAA) while another responded to MAP, MAA and Mycobacterium intracellulare. A more broadly reactive T-cell clone reacted to MAP1508 which belongs to the esx protein family.


CONCLUSIONS
The presence of MAP reactive T cells with a Th1 or Th1/Th17 phenotype may suggest a possible role of mycobacteria in the inflammation seen in CD. The isolation of intestinal T cells followed by characterization of their specificity is a valuable tool to study the relative importance of different bacteria in CD.
Olsen
Ingrid
I
Department of Animal Health, National Veterinary Institute, Oslo, Norway. ingrid.olsen@vetinst.no
Tollefsen
Stig
S
Aagaard
Claus
C
Reitan
Liv J
LJ
Bannantine
John P
JP
Andersen
Peter
P
Sollid
Ludvig M
LM
Lundin
Knut E A
KE
D000328:Adult; D000368:Aged; D000942:Antigens, Bacterial / Q000276:immunology; D001706:Biopsy; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000382:microbiology*; D002469:Cell Separation; D002999:Clone Cells; D003093:Colitis, Ulcerative / Q000276:immunology / Q000382:microbiology; D003424:Crohn Disease / Q000276:immunology* / Q000382:microbiology / Q000473:pathology*; D016207:Cytokines / Q000378:metabolism; D018604:Epitope Mapping; D004926:Escherichia coli / Q000276:immunology; D005260:Female; D006649:Histocompatibility Antigens / Q000276:immunology; D006801:Humans; D007422:Intestines / Q000276:immunology* / Q000382:microbiology / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D016927:Mycobacterium avium subsp. paratuberculosis / Q000276:immunology*
D000942:Antigens, Bacterial; D016207:Cytokines; D006649:Histocompatibility Antigens