Distributions of levels of antibodies to periodontal pathogens and plasma vitamin C concentrations. Distributions of levels of antibodies to periodontal pathogens and plasma vitamin C concentrations. Serum IgG class antibodies to A. actinomycetemcomitans (A) and P. gingivalis (B) were determined by multiserotype ELISA, and plasma vitamin C concentrations (C) were determined by o-phtaldialdehyde-fluorometry, The sample comprised 194 Finnish men and 237 Russian men. Pirkko J. Pussinen et al. Clin. Diagn. Lab. Immunol. 2003; doi:10.1128/CDLI.10.5.897-902.2003