Detection of blood proteins in ancient human bone using ELISA: A comparative study of the survival of IgG and albumin

Abstract

AbstractABSTRACT The immunological identification of species‐specific blood proteins in skeletal remains has an important role in the reconstruction of ancient dietary, ritual and domestic behaviour. However, which protein provides the most suitable target for such work has not been considered previously, and the present investigation was carried out on human bone to assess the relative merits of IgG and albumin.Extracts of bone from 31 individuals (from the English Civil War, medieval, Early Saxon, Roman, Iron Age and Bronze Age periods) were tested by an enzyme‐linked immunosorbent assay (ELISA) using monoclonal antibodies. Albumin was detected in 23 of the 31 skeletons, including those from the Iron and Bronze Ages, whereas IgG was identified in only one; this difference was very highly significant (P < 0.0005, χ2 30.0). The better detection rate for albumin was thought to be due to its higher original blood level, inherent differences in survival pattern being considered unlikely. Testing the same extract for both proteins in the same assay system ensured that any effects due to soil factors, burial conditions, physical integrity of the bone, chronological age, amount of original specimen, method of analysis and type of reagent were the same for each part of the study, thus permitting a valid comparison of antigen survival to be made. Control samples, including fresh and ancient animal bone extracts and human and animal sera, confirmed that the results were consistent and specific, with no cross‐reactivity between human and animal material, and that as little as 10 ng of protein was detectable.In summary, the investigation compared the suitability of IgG and albumin for osteoarchaeological studies using a highly specific, sensitive and versatile ELISA; the results showed that albumin was a far better target molecule for such work and that it can survive in ancient bone for long periods of time.