Macrophage-lysis mediated by autoantibodies to heat shock protein 65/60.
Macrophages in atherosclerotic lesions have been shown to express high amounts of heat shock protein 60 (hsp60), a highly conserved protein. Patients with atherosclerosis have high titers of anti-hsp65/60 antibodies (Ab) recognizing macrophages in the lesions. To elucidate the role of anti-hsp65/60 Ab in macrophage cytotoxicity, human high titer serum and purified anti-hsp65/60 Ab were tested on in vitro heat-stressed cells of a human macrophage cell line (U937) and macrophages derived from peripheral blood. Application of heat stress at 42 degrees C for 30 min resulted in marked upregulation of hsp60 mRNA, followed by increased protein expression as determined by Northern blot and FACS-analysis, respectively. Compared to unstressed cells, high titer serum and anti-hsp65/60 Ab preferentially bound to the surface of stressed U937 macrophages, but not control antibodies. Furthermore, high titer serum and anti-hsp65/60 Ab exerted significant (P < 0.01) complement-mediated cytotoxicity and antibody-dependent cellular cytotoxicity (ADCC) on stressed 51Cr-labelled U937 and peripheral blood derived macrophages. Thus, macrophages expressing hsp60 can be lysed by autoantibodies against hsp65/60, which may contribute to cell death in atherosclerotic plaques in vivo.
Schett
G
G
Institute for Biomedical Aging Research, Austrian Academy of Sciences, Innsbruck, Austria.
Metzler
B
B
Mayr
M
M
Amberger
A
A
Niederwieser
D
D
Gupta
R S
RS
Mizzen
L
L
Xu
Q
Q
Wick
G
G
D000920:Antibody-Dependent Cell Cytotoxicity; D001161:Arteriosclerosis / Q000276:immunology / Q000503:physiopathology; D001323:Autoantibodies / Q000032:analysis*; D001426:Bacterial Proteins; D015152:Blotting, Northern; D002460:Cell Line; D002478:Cells, Cultured; D018834:Chaperonin 60 / Q000276:immunology* / Q000378:metabolism; D018833:Chaperonins / Q000276:immunology* / Q000378:metabolism; D003165:Complement System Proteins / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D006358:Hot Temperature; D006801:Humans; D007136:Immunoglobulins / Q000032:analysis; D008264:Macrophages / Q000276:immunology* / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D015854:Up-Regulation
D001323:Autoantibodies; D001426:Bacterial Proteins; D018834:Chaperonin 60; D007136:Immunoglobulins; D012333:RNA, Messenger; C074119:heat-shock protein 65, Mycobacterium; D003165:Complement System Proteins; D018833:Chaperonins