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

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-1a) levels in diagnosing active TB (aTB) and making a differential diagnosis from other several infectious/non-infectious pulmonary conditions.

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).

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.

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.