Murine hindlimb reperfusion injury can be initiated by a self-reactive monoclonal IgM.
BACKGROUND
Murine hindlimb reperfusion injury (I/R), is initiated by activation of the classical pathway of complement. Complement receptor-2 knockout mice (Cr2-/-) are protected from I/R injury due to defective B-1 cells with a resulting deficient natural immunoglobulin M (IgM) repertoire. Cr2-/- and wild type (WT) mice were studied to isolate the antibody or antibodies responsible for initiation of I/R.


METHODS
IgM-secreting B-1 cell clones were produced with hybridoma technology from WT cells. Of 21 clones tested in murine I/R models, only 1 clone, CM22, was found to restore injury in protected mice. Cr2-/- mice reconstituted with IgM from individual clones, WT serum, or saline were subjected to 2 hours hindlimb ischemia and 3 hours reperfusion and compared with WT.


RESULTS
Muscle injury in Cr2-/- mice reconstituted with CM22 was similar to injury in WT mice reconstituted with saline and Cr2-/- mice reconstituted with WT serum. This injury was 137% greater (P < .05) than in both Cr2-/- mice reconstituted with saline and those reconstituted with a different IgM clone, CM31. IgM and C3 deposition was found only on injured muscle of WT mice or Cr2-/- mice reconstituted with CM22 or WT serum.


CONCLUSIONS
A single clone of self-reactive IgM, CM22, can initiate complement-dependent I/R injury.
Austen
William G
WG
Department of Surgery, Harvard Medical School, the Brigham and Women's Hospital, Boston, MA 02115, USA.
Zhang
Ming
M
Chan
Rodney
R
Friend
Daniel
D
Hechtman
Herbert B
HB
Carroll
Michael C
MC
Moore
Francis D
FD
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D003176:Complement C3 / Q000502:physiology; D006614:Hindlimb / Q000098:blood supply*; D007075:Immunoglobulin M / Q000276:immunology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018482:Muscle, Skeletal / Q000473:pathology; D017464:Receptors, Complement 3d / Q000502:physiology; D015427:Reperfusion Injury / Q000209:etiology* / Q000473:pathology
D000911:Antibodies, Monoclonal; D003176:Complement C3; D007075:Immunoglobulin M; D017464:Receptors, Complement 3d