lgG2 Subclass Deficiency:lgG SubclassAssays

Amongthe four IgG subclassesin humans,IgG2 is preferen-tially expressed in antibodies to carbohydrate antigens whereas IgGi subclass is commonly associated with anti-bodiesto proteinantigens. Because of this associationwith carbohydrate antigens, values for IgG2 in serum are often used as an index of immunocompetenceagainst carbohy-drate antigens. To investigate the value of IgG2 measure-ments in a general population,we have developed a conve-nient lgG subclassassay, using monoclonalantibodiesand particle concentrationfluorescence immunoassay.Our as-say is specific, precise, convenient, and accurate. When IgG2 concentrationswere determinedin the serum samples from 8015 adult blood donors, there were more individuals with low IgG2 concentrationsthan predicted by the log-normaldistribution.The observeddistributionsuggestedth