Potential Role of Interleukin 6 in Reactive Thrombocytosis and Acute Phase Response in Pulmonary Tuberculosis

Objective: Reactive thrombocytosis is found in a number of clinical situations including infectious diseases such as pulmonary tuberculosis (PTB). To examine the possible role of interleukin (IL6) in reactive thrombocytosis and acute phase response in PTB this study measured serum IL6, C reactive protein (CRP), erythrocyte sedimentation rate (ESR), albumin concentrations in 62 PTB patients and 20 healthy volunteers.

Method: PTB patients were divided into two groups based on thrombocyte counts. Twenty seven PTB patients with normal thrombocyte counts constituted group 1, 35 PTB patients with thrombocytosis constituted group 2, and 20 healthy volunteers constituted group 3.

Results: The median IL6 concentration of group 1 was 12.8 pg/ml (95% CI: 12.1 to 56.9 pg/ml) and group 2 was 40.6 pg/ml (95% CI: 67.1 to 168.7 pg/ml). The comparison of IL6 concentrations in the three groups was significant (p = 0.0001). Patients in group 1 had a higher concentration of CRP (p = 0.0001) and lower concentration of albumin (p = 0.002) than group 3 whereas group 2 had higher concentration of CRP (p = 0.003) and lower concentration of albumin (p = 0.002) than group 1. Serum IL6 concentrations were significantly correlated with thrombocyte counts (p = 0.004, r = 0.36), CRP (p = 0.007, r = 0.34), and albumin concentrations (p = 0.005, r = -0.34). IL6 concentrations were significantly correlated with the number of involved zones (p = 0.005, r = 0.35) and acid fast bacilli positivity (p = 0.03, r = 0.27). Patients in group 2 had weight loss (p = 0.004), fever (p = 0.038), and night sweats (p = 0.007) more frequently than group 1. Also, group 2 had more extensive radiological findings (involved zones p = 0.001, bilateral disease p = 0.0001, presence of cavity p = 0.02) than group 1.

Conclusions: IL6 might play a contributory part in reactive thrombocytosis and acute phase response in PTB.