Fluorescent-stainable antibodies to the Eaton agent in human primary atypical pneumonia transmission studies.

Abstract

The etiology of those cases of nonbacterial pneumonia that cannot be associated with the viruses of psittacosis and influenza, adenoviruses, or other well delineated agents, and in which cold hemagglutinins or streptococcus MG agglutinins often develop, has been a controversial subject. The possible role in this disease of an agent isolated by Eaton, Meiklejohn, van Herick and Talbot in 1941 from patients with primary atypical pneumonia (1) has been difficult to evaluate because of the agent's limited host range and technical problems in performing specific serologic tests with it. Eaton's agent can be propagated in embryonated hens' eggs, as demonstrated by production of pneumonia on passage to cotton rats (2), but produces no apparent pathologic change in the chick embryo (2, 3). Using a modification of the fluorescent antibody technique of Coons and Kaplan (4), Liu, Eaton and Heyl have provided both a means of localizing the antigens in the chick embryo and a method by which sera can le examined for fluorescent-stainable antibodies to Eaton's agent (3, 5). Additional isolations of Eaton's agent from patients and demonstrations of fluorescent-stainable antibodies to it have been reported by Cook (6) and Chanock (7) and their associates, confirming and extending the observations of Eaton and Liu. The specificity of this fluorescent antibody reaction in terms of the etiology of the disease has been questioned (8), however, since patients with primary atypical pneumonia may develop a number of nonspecific