Bacterial identification using nitrocellulose blotting technique that incorporates ELISA to bacterial surface antigen.

The weakening of the Clq binding may be explained by the increase in ionic strength (which is known to decrease Clq binding,2 caused by the addition of edetic acid and subsequent neutralisation of the buffer. The relatively high concentration of C3 in serum and the cascade nature of the classical complement activation pathway may explain the C3-binding observed in this experiment. In any event, the binding of complement components to aggregated y-globulin did not seem to be due to non-specific adherance, but rather the biological integrity of the classical complement activation pathway. The ability of the assay to measure different rates of complement consumption was measured by preincubating the complement source (37°C for 30 minutes) in the presence of aggregated y-globulin at concentrations of 1, 2-5, and 10 pg/ml. In these experiments a clear dose dependent decrease in complement activity was observed (fig 2). Much higher concentrations of aggregated y-globulin were needed to cause a decrease in complement binding in the immunofluorescence assay (100-500 pg/ml for Clq and 100 ug/ml for C4 and C3.4 The different inhibition profiles may reflect differences in the complement binding structures used in the assays. The ELISA method described here only responded to functionally intact complement and at much lower serum concentrations than the immunofluorescence assay (fig 1). With minor modifications-that is, by changing the anticomplement serum-the same assay records three different components of the classical complement activation pathway (Clq, C4, and C3). The assay also recorded different amounts of complement activity (fig 2), indicating that it could become a simple and useful method for the measurement of complement activity in serum samples.