Macro-creatine kinase type 1. Immunological studies in 14 patients with comments on clinical significance

Circulating autoantibodies directed at creatine kinase (CK) BB isozyme are detected in plasma in the form of an immune complex (immunoglobulin CK BB) termed macro-CK type 1. Fourteen patients presented a falsely elevated CK MB isozyme fraction as measured by the immunoinhibition method; they were found to have IgG-CK BB complexes, which was considered to be indirect evidence of circulating anti-CK BB autoantibodies. No evident clinical association between the detection of this autoantibody in complexed form and autoimmune disease could be established, there was no significantly increased incidence of other autoantibodies, and there was no specific alteration in immunoglobulin and complement levels; however, the HLA haplotype A1,B8,DR3, which is known to be associated with autoimmunity, was present in five patients.