Influence of chronic lead ingestion on IgG subclass expression of the immune response to bovine serum albumin.

Rats were given free access to drinking water containing 2% lead acetate for 30 days prior to intraperitoneal inoculation with 100 mcg of bovine serum albumin (BSA) in Freund's complete adjuvant. Three weeks later, the animals were boosted with the antigen in Freund's incomplete adjuvant. After an additional three weeks, the animals were bled and the sera assayed for total IgG by radial immunodiffusion and for specific IgM, IgG and IgG subclasses by the enzyme-linked immunosorbent assay (ELISA). BSA-inoculated rats exhibited similar levels of total IgG regardless of exposure to lead, but showed significant increases in IgG compared to nonimmunized controls. However, levels of IgG specific for BSA were significantly lower in the lead exposed group. Analysis of the IgG subclasses specific for BSA revealed that BSA-inoculated rats which were not exposed to lead had greater titers of IgG2b and IgG2c as compared to the lead exposed group. Chronic lead ingestion appears to diminish the overall IgG response to BSA and may alter the normal IgG subclass expression.