Serological Testing for Mycobacterial Heat Shock Protein <i>Hsp65</i> Antibody in Health and Diseases

Mycobacterial heat shock protein 65 gene (<i>Hsp65</i>) has been widely used for classification of Mycobacterial species, and detection of Mycobacterial genes by molecular methods and has proven useful in identification of Mycobacterial infection in various clinical conditions. Circulating antibody against Mycobacterial <i>hsp65</i> has been found in many clinical diseases including autoimmune diseases (Crohn&#8217;s disease, lupus erythematosus, multiple sclerosis, diabetes, etc.), atherosclerosis and cancers. The prevalence of anti-<i>Hsp65</i> antibody in the normal healthy population is unknown. We determined the blood levels of antibody against Mycobacterial <i>hsp65</i> in the normal population represented by 288 blood donors of the American Red Cross and tested the blood of 109 patients with Crohn&#8217;s disease and 28 patients with Sjogren&#8217;s syndrome for comparison. The seroprevalence of anti-<i>Hsp65</i> IgG in the normal population of Red Cross donors was 2.8% (8 of 288 positive). The <i>Hsp65</i> antibody levels were significantly elevated in patients with Crohn&#8217;s disease and Sjogren&#8217;s syndrome. The prevalence of <i>Hsp65</i> antibody in Crohn&#8217;s disease patients was 67.9% (74 of 109 patients), and 85.7% for Sjogren&#8217;s patients (24 of 28 patients). Our data indicate that anti-<i>Hsp65</i> antibody is rare in the normal population, but frequent in chronic diseases. The presence of circulating <i>Hsp65</i> antibody reflects an abnormal immune (adaptive) response to Mycobacterial exposure in patients with chronic diseases, thus differentiating the patients with chronic diseases from those clinical mimics.