Effect of plasma lysozyme on live Mycobacterium tuberculosis

The role of plasma lysozyme of normal healthy subjects (NHS, n = 12) and active pulmonary tuberculosis (ATB) patients (n = 15) on the innate immune mechanism was studied by the binding activity of lysozyme on live Mycobacterium tuberculosis. Plasma samples of NHS and ATB patients treated with live M. tuberculosis for 4 h and 24 h time points showed a significant decrease in the plasma lysozyme level when compared to the untreated samples (4 h, P < 0.001; 24 h, P < 0.001). Pretreatment of live M. tuberculosis with plasma of NHS and ATB patients showed a trend in the reduction of viability of live M. tuberculosis. Moreover, M. tuberculosis pretreated plasma of NHS showed a trend towards an increased spontaneous as well as antigen-induced lymphocyte response when compared to ATB plasma. The enzymatic action of the lysozyme and other enzymes on the cell wall may induce M. tuberculosis to release some antigenic components which may be immunogenic and induce lymphocyte proliferation. The present study suggests that lysozyme and other enzymes may play an important role in the first line defence, i.e. the innate immunity, against M. tuberculosis infection.