Myalgic encephalomyelitis (ME, also called
Chronic Fatigue Syndrome), a common disease with chronic fatigability,
cognitive dysfunction and
myalgia of unknown etiology, often starts with an
infection. The
chaperonin human
heat shock protein 60 (HSP60) occurs in mitochondria and in bacteria, is highly conserved, antigenic and a major
autoantigen. The anti-HSP60 humoral (
IgG and
IgM) immune response was studied in 69 ME patients and 76 blood donors (BD) (the Training set) with recombinant human and E coli HSP60, and 136 30-mer overlapping and targeted
peptides from HSP60 of humans, Chlamydia, Mycoplasma and 26 other species in a multiplex
suspension array.
Peptides from HSP60 helix I had a
chaperonin-like activity, but these and other HSP60
peptides also bound
IgG and
IgM with an ME preference, theoretically indicating a competition between HSP60 function and antibody binding. A HSP60-based panel of 25
antigens was selected. When evaluated with 61 other ME and 399 non-ME samples (331 BD, 20
Multiple Sclerosis and 48
Systemic Lupus Erythematosus patients), a
peptide from Chlamydia pneumoniae HSP60 detected
IgM in 15 of 61 (24%) of ME, and in 1 of 399 non-ME at a high cutoff (p<0.0001).
IgM to specific cross-reactive
epitopes of human and microbial HSP60 occurs in a subset of ME, compatible with
infection-induced autoimmunity.