Abstract
IN the blood of dogs infected with kala-azar, proteins are precipitated on cooling to room temperature (20° C), or better still when allowed to stand in the ice-box (5° C.) overnight. This protein belongs to the pathologically increased euglobulin fraction. In twenty-one sera investigated (six cases) the cold fraction test was positive. In typical specimens, turbidity soon followed by precipitation sets in within a quarter of an hour of standing in the ice-box. The protein precipitated from kala-azar serum on cooling (cold fraction) is defined as the centrifugable protein fraction which precipitates after 24 hr. at 5°C, and is redissolved by warming to37°–50°C. This cold fraction ranged between traces of turbidity which could not be determined quantitatively to maximal 3 gm. per 100 c.c. of serum. Typical cases gave tests as shown in the accompanying table:
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STEIN, L., WERTHEIMER, E. Proteins Susceptible to Cold in Pathological Sera. Nature 149, 528 (1942). https://doi.org/10.1038/149528a0
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DOI: https://doi.org/10.1038/149528a0
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