FIG 4.

Therapeutic MAbs can be measured simultaneously by miRAMM. In this example, several therapeutic MAbs were used to spike commercially available normal human serum. A given therapeutic MAb's specific light chain will have a unique mass and be distinguishable from the endogenous Ig background when present in large concentrations. The extracted ion spectrum shows the +11 charge state of five MAbs' specific light chains detected above the human serum polyclonal Ig background. Although it is highly unlikely that a patient would not be undergoing therapy with five or six different MAbs at the same time, the multiplex capability allows application of the technique for screening methods, such as the differentiation of a therapeutic MAb from a disease-causing endogenous monoclonal protein.