Humoral immunity in root caries in an elderly population. 1

IgA, IgG and IgM antibody activity (ELISA Units/ml) to Streptococcus mutans, Actinomyces viscous and Escherichia coli CF8 in serum, parotid saliva and whole saliva was measured using the amplified ELISA (a-ELISA) while the concentration (microgram/ml) of each isotype of immunoglobulin as well as albumin and lactoferrin, was determined using sandwich ELISAs. Selection of suitable reagents from those commercially available was based on specificity tests using purified human immunoglobulin; most polyclonal reagents required further absorption to attain class specificity. Cross-absorption studies indicated the absence of patient antibodies that were cross-reactive among the bacteria studied, except for IgM in some cases. Expression of response in ELISA Units (E.U.) per microgram of immunoglobulin, i.e. specific activity, revealed that IgG specific activity was significantly higher in parotid saliva than in either whole saliva or serum for all bacteria studied; serum and whole saliva did not differ except for the higher specific activity in whole saliva to E. coli. The value of one E.U. was determined using the Comparative Antibody-immunoglobulin Capture Assay (CACA). Using this novel method, we estimated that about 0.05 percent of serum IgA was specific for Streptococcus mutans, 0.008 for Actinomyces viscosus and 0.004 for Escherichia coli CF8. The percentage of specific IgM antibodies was higher than for IgA and IgG. The concentration of IgA anti-Streptococcus mutans, Actinomyces viscosus and Escherichia coli levels are approximately 92 ng/ml, 25 ng/ml and 16 ng/ml in whole saliva and 46 ng/ml, 9.4 ng/ml and 6.3 ng/ml in parotid saliva.(ABSTRACT TRUNCATED AT 250 WORDS)