Epigenetics & Chromatin

S-Adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) are relevant to a variety of diseases. Previous reports that quantifi ed SAM and SAH were based on HPLC or LC–MS/MS. No antibody against SAM has been generated and the antibody against SAH could not be used with blood samples. Immunoassays have not been used to measure SAM and SAH. In this study, ELISA was used to measure blood SAM and SAH levels. Specifi c antibodies against SAM were produced for the fi rst time using a stable analog as the antigen. The monoclonal antibodies against SAM and SAH were characterized. No cross-reactivity was detected for the analyzed analogs. Using high-quality antibodies against SAM and SAH, immunoassays for the detection of SAM and SAH levels in blood and tissue samples were developed. Clinical investigations using immunoassays to measure SAM, SAH and the methylation index (MI) in normal and diseased samples indicated that the SAM level is age and gender dependent; the SAM level is associated with the severity of liver diseases, infl ammatory reactions and other diseases; and the methylation index (MI) is signifi cantly reduced in many diseases and may serve as a screening biomarker to identify potentially unfavorable health conditions. Our conclusions include that it is possible to generate antibodies against active small biomolecules with weak immunogenicity, such as SAM and SAH, using traditional hybridoma technology. The antigens and antibodies described here will contribute to the development of immunoassays to measure SAM, SAH and related molecules. These assays enable the MI to be measured timely (essential for unstable molecules), specifically, accurately, easily and quickly without costly equipment. This preliminary study indicates that the MI could be an eff ective indicator of general health, except for special conditions that may alter the value of the MI, such as certain diets and medications.