Functional estimation of mannose binding lectin associated serine protease (MBL-MASPs) in human serum.

BACKGROUND & OBJECTIVE Mannose binding lectin (MBL), a C-type or Ca(2+) dependent lectin, plays a major role in lectin pathway of complement activation. MBL deficiency/insufficiency is associated with susceptibility to many infections. It is important to know the association of functional lectin levels with disease condition. Therefore, we carried out this study to develop a simple assay to estimate the functional MBL-associated serine proteases (MBL-MASPs) levels in human serum samples. METHODS A novel method was developed based on direct haemolysis of mannan coated human erythrocytes in autologous human serum for functional estimation of MBL and associated serine proteases (MBLMASPs complex). Functional MBL-MASPs serum levels in 75 healthy individuals was estimated. Results were compared with those obtained by ELISA based assay. RESULTS Lysis of mannan coated human RBC in autologous serum was highly specific and mediated by MBL-MASPs lectin complement pathway. Concentration of MBL-MASPs in serum of normal healthy individuals (n=75) was found to be 1.579 mug/ml (median= 1.149 mug/ml) by the haemolytic assay which was comparable to the values obtained by ELISA method. INTERPRETATION & CONCLUSION Our findings showed that the method developed for the estimation of functional MBL-MASPs levels in human serum is simple, cost-effective and comparable with existing ELISA method.