Antibody Heterogeneity in Experimental Listeriosis

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Abstract
Summary: In uninoculated sheep and cattle, IgM antibodies to Listeria monocytogenes types 1, 2 and 4b were uniformly demonstrable. The 7S antibodies were divided into subclasses designated “slow IgG” and “fast IgG.” It was noteworthy that only one sheep in a group of 12 ruminants had 7S antibodies (slow IgG) to Listeria serotype 4b prior to immunization. Thus the basis for antibody activity in the serum of apparently normal animals is largely a function of the IgM class of immunoglobulins. All immunized animals synthesized both subclasses of 7S antibodies. Results were less distinctive on studies with Listeria types 1 and 2, Staphylococcus aureus and Streptococcus faecalis. Among four sheep studied in detail all contained IgM agglutinins prior to immunization, in addition to variable distribution of 7S antibody populations reacting with the four microorganisms. Whole serum titers to Listeria types 1 and 2 were not markedly increased by immunization of the animals with the Streptococcus or Staphylococcus. However, titers did increase following the inoculation of live Listeria cells into the same animals. The detection of IgG agglutinins to Listeria type 4b in serum after reduction of IgM globulins with 2-mercaptoethanol would appear to have diagnostic significance.