[Stability of specific antibodies in blood collected on filter paper disks]

Immunoglobulin G (IgG) and M (IgM) stability in serum samples collected on filter paper disks and stored at different temperatures was evaluated. IgG and IgM concentration measured by immunonephelometry was fairly stable for 4 weeks at 4 degrees C, whereas it decreased to about 50% of total at room temperature and at 37 degrees C. By ELISA, no significative loss in antibody activity of IgG was observed after 6 months at 4 degrees C. At 37 degrees C the loss was greater but still acceptable. Antibody activity of IgM decreased more rapidly than that of IgG: IgM were stable at -20 degrees C, whereas had a significative loss of activity after 5 weeks both at 4 degrees C and 37 degrees C. Finally, it is to note that a storage in saturated water vapour seems not to interfere with immunoglobulins stability.