Poor preservation of antibodies in archaeological human bone and dentine

The growth of proteomics-based methods in archaeology prompted an investigation of the survival of non-collagenous proteins, specifically immunoglobulin G (IgG), in archaeological human bone and dentine. Over a decade ago reports were published on extracted, immunoreactive archaeological IgG, and the variable yields of IgG molecules detected by Western blots of 1D and 2D SDS-PAGE gels. If IgG can indeed be recovered from archaeological skeletal material, it offers remarkable opportunities for exploring the history of disease - for example in applying functional anti-malarial IgGs to study past patterns of malaria. More recently, the field has seen a move away from immunological approaches and towards the use of shotgun proteomics via mass spectrometry. Using previously published techniques, this study attempted to extract and characterize archaeological IgG proteins. In only one extraction method were immunoglobulin derived peptides identified, and these displayed extensive evidence of degradation. The failure to extract immunoglobulins by all but one method, along with observed patterns of protein degradation, suggests that IgG may be an unsuitable target for detecting disease-associated antigens. This research highlights the importance of revisiting previously ‘successful’ biomolecular methodologies using emerging technologies.