Precipitating polyclonal goat antiserum to cat immunoglobulins, heavy and light chains. Human standard Serum with assigned values for IgG subclasses. ... The determination of the concentration of each of the four subclasses was carried out by single radial immunodiffusion (RID, Mancini) in agar gel using subclass-specific polyclonal antisera and the WHO reference serum 67/97 as the primary standard. The nephelometric determination of the concentration of each of the four subclasses was carried out on a Beckman Coulter IMMAGE