QUANTITATION OF GM ALLOTYPES

A method for quantitation of Gm allotypes is described. Alternative Gm allotypes of the three IgG subclasses, IgG1, IgG2 and IgG3, were investigated for the six most common Caucasian Gm phenotypes. Quantitation of G1m(a), G1m(f) of IgG1, G2m(n) of IgG2 and G3m(b) of IgG3 was performed with specific monoclonal antisera and purified myeloma proteins of different Gm allotypes. Mean +/- SD are given as percentage of a normal serum pool and in g/l for the Gm allotypes G1m(a), G1m(f), G2m(n) and G3m(b). For homozygous individuals the G2m('','') values are equal to the IgG2 levels and the G3m(g,g) values equal to the IgG3 levels. For heterozygous individuals the value for G2m('') is calculated as IgG2 minus G2m(n) and for G3m(g) as IgG3 minus G3m(b). Homozygous individuals have about double the amounts of the Gm allotype compared with heterozygous individuals. The gene activity of heterozygous individuals is given by quotients, mean +/- SD for G1m(a)/G1m(f) of IgG1, G2m(n)/G2m('') of IgG2 and G3m(b)/G3m(g) of IgG3 in different Gm phenotypes. Heterozygous individuals on all three IgG subclass loci have at least six different qualities of IgG molecules compared with three for homozygous individuals.