Effect of lipid-extraction on precipitating antisera

Abstract

The technique for removal of the ether fraction which remains dissolved in the serum after the extraction of lipids with ether is described. Lipid-extraction, though it does not affect the antibody (serum-antigen) titre, is not
recommended for antisera which are intended mainly for meat investigation work. Lipid extraction substantially lowers the sensitivity of an antiserum against homologous meat and it is then less reliable for detection of small amounts of foreign meat in a meat mixture. Such unextracted antisera, however, cannot always be freeze-dried or stored in the cold, as about 75% of rabbit sera will develop an opalescence, sometimes very pronounced, when exposed to temperatures below -25 ° C. for longer than a few days. They have to be kept therefore in liquid state (4 ° C.), though some deterioration in the antibody titre is likely to follow after storage for longer than 6 months. In lipid-extracted antisera low temperatures do not cause any adverse effect in the physical properties or antibody titre. Storage in the frozen state is therefore recommended for such antisera, as it makes the time-consuming freeze-drying process unnecessary.