Complement Fixation with Dissimilar Antigens in Primary Atypical Pneumonia

Abstract

In complement-fixation tests with sera from patients with primary atypical pneumonia of unknown etiology, it was found unexpectedly that the convalescent serum from a number of patients reacted positively in high dilution with various and apparently unrelated antigens. Since this peculiar and as yet unexplained property can lead to difficulty in the interpretation of the results of complement-fixation tests with sera obtained from patients with this clinical syndrome the phenomenon has been studied. Materials and Methods. Specimens of serum were obtained from patients acutely ill with primary atypical pneumonia in the Rockefeller Hospital. Additional specimens of serum were obtained from these patients throughout the course of the illness and during convalescence. The sera were stored at 4°C. Mouse lung antigens. Antigens were prepared from the lungs of normal albino Swiss mice and from the lungs of similar mice which had been infected with one or another of the following viruses: a. pneumonia virus of mice, Horsfall and Hahn; b. influenza A virus, PR8 strain; c. cat pneumonitis virus, Baker; and d. meningo-pneumonitis virus. Mice infected with agents a, b, and d were killed usually on the fifth day after intranasal inoculation, while mice infected with agent c were killed on the second day. The lungs were removed aseptically, ground with abrasive and suspended in a final concentration of 2% by wet weight in 0.85% NaCl buffered at pH 7.2. The suspension was centrifuged at 1500 RPM for 10 minutes and the supernate withdrawn and used as antigen. When parallel tests were done with different antigens they were all prepared on the same day from mouse lungs which either had been freshly removed or stored as intact specimens at −70°C for some days. Other tissue antigens. Antigens were prepared also in a manner identical with that described above from the following individual normal tissues: mouse liver. mouse spleen, rabbit lung, rabbit liver, rabbit spleen, rabbit kidney, guinea pig lung, hooded rat lung.