Antigenic detection of tuberculosis infection has been a goal for quite some time, and mannose-capped lipoarabinomannan has seemed a promising biomarker for this use. Initial attempts to employ ManLAM in TB diagnostics were not particularly successful, owing to a later-discovered matrix effect that renders ManLAM in serum, urine, and other body fluids poorly detectable by immunometric assays. In short, ManLAM complexes with some endogenous protein(s) and is sterically hindered from being bound by antibodies at either the capture or labeling step.

In this work, a continuation of ongoing Porter Group efforts to develop a pretreatment to free ManLAM from its complexes, we showed that digestion with proteinase K frees ManLAM from its complexes with quantitative recovery. The pretreatment process yields a small preconcentration as well, which is easily corrected for by gravimetric analysis of the sample.