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Quantitative analysis of immunoglobulin G subclasses in the rat
1Department of Biochemistry, Medical College of Pennsylvania, Philadelphia 19129.
Quantitative ELISAs have been developed for the four immunoglobulin G (IgG) subclasses (IgG1, IgG2a, IgG2b and IgG2c) of the rat. These assays were shown to have excellent sensitivity, reproducibility and adequate specificity for studies of natural IgG and antigen-elicited IgG responses. The sensitivity (working range for each isotype assay) was: IgG1, 1.6 to 200 ng/ml; IgG2a, 8 to 200 ng/ml; IgG2b, 1.6 to 200 ng/ml; and IgG2c, 1.6 to 1000 ng/ml. The isotype sum and the direct assay of total plasma IgG agreed closely. The utility of these assays was demonstrated in a study of the development of total IgG and of the specific IgG response following immunization with tetanus toxoid (TT). For total IgG, the predominant isotype was IgG2b (64% of total IgG) followed by IgG2a (29%), IgG1 (4%) and IgG2c (3%). In contrast, the anti-TT response was mainly of the IgG1 subclass (57% of total anti-TT). These quantitative assays should prove useful for investigating the response to experimental vaccines and the influence of cytokines on class switching in vivo.
Quantitative ELISAs have been developed for the four immunoglobulin G (IgG) subclasses (IgG1, IgG2a, IgG2b and IgG2c) of the rat. These assays were shown to have excellent sensitivity, reproducibility and adequate specificity for studies of natural IgG and antigen-elicited IgG responses. The sensitivity (working range for each isotype assay) was: IgG1, 1.6 to 200 ng/ml; IgG2a, 8 to 200 ng/ml; IgG2b, 1.6 to 200 ng/ml; and IgG2c, 1.6 to 1000 ng/ml. The isotype sum and the direct assay of total plasma IgG agreed closely. The utility of these assays was demonstrated in a study of the development of total IgG and of the specific IgG response following immunization with tetanus toxoid (TT). For total IgG, the predominant isotype was IgG2b (64% of total IgG) followed by IgG2a (29%), IgG1 (4%) and IgG2c (3%). In contrast, the anti-TT response was mainly of the IgG1 subclass (57% of total anti-TT). These quantitative assays should prove useful for investigating the response to experimental vaccines and the influence of cytokines on class switching in vivo.