Diagnostic and prognostic value of CXCL12 (SDF-1α) level in Mycobacterium tuberculosis infection and disease

Introduction: New diagnostic tools are being investigated for rapid and accurate TB detection. We aimed to find out the diagnostic yield and accuracy of chemokine CXCL12 (SDF-1 alpha) levels in diagnosing active TB (aTB) and making a differential diagnosis from other several infectious/non-infectious pulmonary conditions. Methodology: We collected demographic, clinic features and studied plasma CXCL12 levels using ELISA kit of the participants, classified into five categories: aTB (n = 30); cured TB (cTB, n = 15); close contacts of aTB (CC, n = 15); chronic obstructive pulmonary disease (COPD) with active nonspecific pulmonary infection (infCOPD, n = 15); and healthy controls (HC, n = 15). Results: CXCL12 levels were highest in aTB, but no significant difference was seen between other groups. When a cut-off level for CXCL12 was determined as 2835 pg/mL, the increased CXCL12 rate was significantly more in aTB than CC and HC (p = 0.02, p = 0.05). Also, participants with an active infection (aTB and infCOPD) had significantly higher increased CXCL12 rates (p = 0.01). The sensitivity and specificity of CXCL12 for diagnosing aTB were found to be 0.56 and 0.63, respectively. We found that bacterial load, the radiological severity and the extent of chest x-ray involvement were independent factors for increased CXCL12 levels. Conclusions: Our study demonstrates that CXCL12 may be a representative of active pulmonary infection regardless of the cause but correlated with the severity of the disease; enabling this test to be used as a prognostic factor rather than a diagnostic test for aTB.