STUDIES ON IMMUNITY IN ANTHRAX. 11. CONTROL OF CELLULAR PERMEABILITY BY BICARBONATE ION IN RELATION TO PROTECTIVE ANTIGEN ELABORATION
ARMY BIOLOGICAL LABS FREDERICK MD
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No elaboration of Bacillus anthracis protective antigen was demonstrated after addition of bicarbonate to cultures incubated 42 hr in a bicarbonate-free medium. Antigen accumulation in culture filtrates was greater if the bicarbonate was added to these cultures early in the growth period. Cell-free extracts of washed cell suspensions, prepared by hand grinding or lysozyme treatment, had no demonstrable intracellular protective antigen. Sonic treatment released antigen in measurable amounts, but tended to destroy or degrade the labile antigen. Freezing and thawing disrupted the cells and liberated the antigen protective antigen was shown to be of internal rather than of extracellular origin. Maximal intracellular antigen concentration occurred before the peak concentration was reached in the culture filtrates. Antigen also was found in cell extracts from bicarbonate-free culture media when none was present in the corresponding culture filtrates. A high level of internal protective antigen was present in cells grown in a bicarbonate-free medium maintained at a constantly alkaline pH only a trace of antigen was present in the corresponding pH-adjusted culture filtrate. The hypothesis is presented that bicarbonate functions to control cellular permeability and release of antigen from the cells into the ambient medium.