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

ABSTRACT

Background & objectives: Mannose binding lectin (MBL), a C-type or Ca2+ 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 μg/ml (median= 1.149 μg/ml) by the haemolytic assay which was comparable to the values obtained by ELISA method. Interpretation & conclusions: 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.