Neutrophil phagocytic activity in differentiating tuberculosis from sarcoidosis

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Introduction: Similarities between sarcoidosis (SA) and tuberculosis (TB) may cause a dangerous misdiagnosis. Therefore, there are searches for new biomarkers discriminating SA from TB. We revealed that genetically different SA or TB patients induce dissimilar immune responses to the same mycobacterial heat shock proteins, which are implicated in forming of immune complexes (CIs). The complexemia in both diseases may be a result of altered abilities of monocytes and/or neutrophils to phagocytosis/clearance CIs with following persistent antigenemia and granuloma formation. Method: We evaluated the phagocytic activity of blood monocytes and neutrophils in 25 SA patients, 25 TB patients and 20 healthy volunteers (C) using the PHAGOTEST kit by flow cytometry. Results: The total number of white blood cells was higher in TB than in SA and C (p=0.003, p=0.02) with no difference between SA and C.The total number of monocytes was higher in SA than in TB and C (p=0.002, p=0.002), as well in TB compared to C (p=0.04). The phagocytic activity of monocytes was higher in SA compared to C (p=0.03), whereas there was no difference between TB and C. The total number of neutrophils is increased in TB compared to SA and C (p=0.0004, p=0.01) with no difference between SA and C. Phagocytic activity of neutrophils was higher in TB than in SA and C (p=0.004, p=0.01), whereas there was no difference between SA and C. Conclusion: Our results revealed an increase in phagocytic activity of monocytes in both diseases, whereas in TB was detected an increased activity of neutrophils than in SA. Phagocytic activity of blood neutrophils might prove useful for diferentiation of SA from TB. Study founded: grant 02-127/07/232.