Signal regulatory protein alpha (SIRPalpha) cells in the adaptive response to ESAT-6/CFP-10 protein of tuberculous mycobacteria.
BACKGROUND
Early secretory antigenic target-6 (ESAT-6) and culture filtrate protein-10 (CFP-10) are co-secreted proteins of Mycobacterium tuberculosis complex mycobacteria (includes M. bovis, the zoonotic agent of bovine tuberculosis) involved in phagolysosome escape of the bacillus and, potentially, in the efficient induction of granulomas. Upon tuberculosis infection, multi-nucleate giant cells are elicited, likely as a response aimed at containing mycobacteria. In tissue culture models, signal regulatory protein (SIRP)alpha (also referred to as macrophage fusion receptor or CD172a) is essential for multi-nucleate giant cell formation.


RESULTS
In the present study, ESAT-6/CFP-10 complex and SIRPalpha interactions were evaluated with samples obtained from calves experimentally infected with M. bovis. Peripheral blood CD172a(+) (SIRPalpha-expressing) cells from M. bovis-infected calves proliferated upon in vitro stimulation with ESAT-6/CFP-10 (either as a fusion protein or a peptide cocktail), but not with cells from animals receiving M. bovis strains lacking ESAT-6/CFP-10 (i.e, M. bovis BCG or M. bovis DeltaRD1). Sorted CD172a(+) cells from these cultures had a dendritic cell/macrophage morphology, bound fluorescently-tagged rESAT-6:CFP-10, bound and phagocytosed live M. bovis BCG, and co-expressed CD11c, DEC-205, CD44, MHC II, CD80/86 (a subset also co-expressed CD11b or CD8alpha). Intradermal administration of rESAT-6:CFP-10 into tuberculous calves elicited a delayed type hypersensitive response consisting of CD11c(+), CD172a(+), and CD3(+) cells, including CD172a-expressing multi-nucleated giant cells.


CONCLUSIONS
These findings demonstrate the ability of ESAT-6/CFP-10 to specifically expand CD172a(+) cells, bind to CD172a(+) cells, and induce multi-nucleated giant cells expressing CD172a.
Waters
W Ray
WR
National Animal Disease Center, Agricultural Research Service, U.S. Department of Agriculture, Ames, Iowa, United States of America. ray.waters@ars.usda.gov
Palmer
Mitchell V
MV
Nonnecke
Brian J
BJ
Thacker
Tyler C
TC
Estes
D Mark
DM
Larsen
Michelle H
MH
Jacobs
William R
WR
Andersen
Peter
P
McNair
James
J
Minion
F C
FC
Lyashchenko
Konstantin P
KP
Hewinson
R Glyn
RG
Vordermeier
H Martin
HM
Sacco
Randy E
RE
D000818:Animals; D000942:Antigens, Bacterial / Q000502:physiology*; D001426:Bacterial Proteins / Q000502:physiology*; D002417:Cattle; D008297:Male; D009163:Mycobacterium bovis / Q000502:physiology*; D009169:Mycobacterium tuberculosis / Q000502:physiology*; D010446:Peptide Fragments / Q000502:physiology*; D011971:Receptors, Immunologic / Q000502:physiology*
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C489634:CFP-10 protein (71-85), Mycobacterium tuberculosis; C093276:ESAT-6 protein, Mycobacterium tuberculosis; D010446:Peptide Fragments; D011971:Receptors, Immunologic