Importance of Local Antibody in Resistance to Mycoplasma Infections of the Respiratory Tract

Abstract

A solid-phase micro-radioimmunoassay was used to study the development of class-specific antibodies to Mycoplasma pulmonis in sera and lung washings of mice after inoculation with live or inactivated mycoplasmas by a variety of routes. Attempts were made to correlate these findings with resistance to a subsequent intranasal challenge with M. pulmonis. These investigations indicated that resistance to M. pulmonis in mice correlated with the presence of antibody in lung washings and that antibody of any Ig class may mediate resistance. Similar studies in calves vaccinated with inactivated M. bovis also suggested that antibody in lung washings is important in resistance and that this antibody was predominantly IgG.

Further evidence that antibody of any Ig class in the respiratory tract can mediate resistance to mycoplasma infections was obtained from an examination of the ability of intranasal administration of purified mouse immtunoglobulins to protect against infection with M. puZmonis. Thus, IgG1 and IgG2a were most effective in protecting mice against infection with M. pulmonis, IgG2b less so and IgA was least effective of all. The ways in which antibodies may mediate resistance to mycoplasma infections are discussed.