Abstract
The neutralization or killing of Mycoplasma pneumoniae by either rabbit or human antiserum required a heat-labile factor from non-immune serum. Killing was rapid, but could be stopped by dilution, thus permitting study of the reaction. The absolute number of organisms killed in a constant time interval was independent of the initial number of organisms present, making this reaction analogous to complement-mediated lysis of sensitized red blood cells. Although the rate of killing was influenced by antibody content, the level of normal serum factor appeared to have a much larger influence on the rate of the reaction. This heat-labile factor is apparently complement or some components of complement: it can be blocked by a chelating agent, is sensitive to salt concentration, and can be removed by prior absorption with a non-related complement-fixing antigen-antibody complex. Killing did not take place at 4°C, suggesting that the reaction is enzymatically controlled. The relative rates of killing appear to parallel lipid CF titers, but the measurement of antibody is 10 times as sensitive.
Footnotes
This study was supported in part by Public Health Service Research Grant AI-06720 and Training Grant TI-AI-206 from the National Institute of Allergy and Infectious Diseases, and by the United States Army Medical Research and Development Command, Department of the Army, (Contract DA-49-193-MD-2294) under the sponsorship of the Commission on Acute Respiratory Diseases, Armed Forces Epidemiological Board.
