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Sarcoidosis may be affected by sex, race, and age. A Case Control Etiologic Study of Sarcoidosis (ACCESS) enrolled 736 patients with sarcoidosis within 6 mo of diagnosis from 10 clinical centers in the United States. Using the ACCESS sarcoidosis assessment system, we determined organ involvement for the whole group and for subgroups differentiated by sex, race, and age (less than 40 yr or 40 yr and older). The study population was heterogeneous in terms of race (53% white, 44% black), sex (64% female, 36% male), and age (46% < 40 yr old, 54% > or = 40 yr old). Women were more likely to have eye and neurologic involvement (chi(2) = 4.74, p < 0.05 and chi(2) = 4.60, p < 0.05 respectively), have erythema nodosum (chi(2) = 7.28, p < 0.01), and to be age 40 yr or over (chi(2) = 6.07, p < 0.02) whereas men were more likely to be hypercalcemic (chi(2) = 7.38, p < 0.01). Black subjects were more likely to have skin involvement other than erythema nodosum (chi(2) = 5.47, p < 0.05), and eye (chi(2) = 13.8, p < 0.0001), liver (chi(2) = 23.3, p < 0.0001), bone marrow (chi(2) = 18.8, p < 0.001), and extrathoracic lymph node involvement (chi(2) = 7.21, p < 0.01). We conclude that the initial presentation of sarcoidosis is related to sex, race, and age.

Sarcoidosis is a disease of unknown etiology characterized by noncaseating epithelioid granulomas, oligoclonal CD4+ T cell infiltrates, and immune complex formation. To identify pathogenic antigens relevant to immune-mediated granulomatous inflammation in sarcoidosis, we used a limited proteomics approach to detect tissue antigens that were poorly soluble in neutral detergent and resistant to protease digestion, consistent with the known biochemical properties of granuloma-inducing sarcoidosis tissue extracts. Tissue antigens with these characteristics were detected with immunoglobulin (Ig)G or F(ab′)2 fragments from the sera of sarcoidosis patients in 9 of 12 (75%) sarcoidosis tissues (150–160, 80, or 60–64 kD) but only 3 of 22 (14%) control tissues (all 62–64 kD; P = 0.0006). Matrix-assisted laser desorption/ionization time of flight mass spectrometry identified Mycobacterium tuberculosis catalase–peroxidase (mKatG) as one of these tissue antigens. Protein immunoblotting using anti-mKatG monoclonal antibodies independently confirmed the presence of mKatG in 5 of 9 (55%) sarcoidosis tissues but in none of 14 control tissues (P = 0.0037). IgG antibodies to recombinant mKatG were detected in the sera of 12 of 25 (48%) sarcoidosis patients compared with 0 of 11 (0%) purified protein derivative (PPD)− (P = 0.0059) and 4 of 10 (40%) PPD+ (P = 0.7233) control subjects, suggesting that remnant mycobacterial catalase–peroxidase is one target of the adaptive immune response driving granulomatous inflammation in sarcoidosis.

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