THE THERMOLABILITY OF COMPLEMENT, IN RELATION 

 TO THE HYDROGEN ION CONCENTRATION. 



By CALVIN B. COULTER.* 



(From the Eoagland Laboratory, Brooklyn.) 



(Received for publication, May 12, 192L) 



That property of fresh blood serum by which it is able to take 

 part in, and complete various immunological reactions is known as 

 complement. The thermolability of this function is well knov/n. 

 In respect to the separated fractions, that contained in the euglob- 

 ulin fraction of the serum and known as mid-piece, and that contained 

 in the pseudoglobulin and albumin fraction and referred to as end- 

 piece, Ferrata^ found only the end-piece thermolabile. Subsequent 

 observers have uniformly found both fractions thermolabile. A num- 

 ber of investigators^' ^> ^ have noted that the mid-piece is more resist- 

 ant when heated in whole serum than when isolated. Leschly^ found 

 moreover that the mid-piece, apparently inactivated by brief heating 

 to 56°C. was able to complete hemolysis when added separately to 

 the sensitized cells, the addition of end-piece being made after an 

 interval, so that under these conditions there is not a permanent 

 destruction, but the development of the modification described by 

 Erand.^ 



With regard to the effect of the chemical reaction it has been known 

 since the observations of Ehrlich and Morgenroth^ and Ehrlich and 

 Sachs^ that the addition of considerable amounts of acid or alkali 



*Van Cott Fellow in Pathology. 

 1 Ferrata, A., Bcrl. Klin. Woch., 1907, xliv, 366. 

 ^ Freidmann, U., Z. Hyg. uitd Infektionskrankh., 1910, Lxvii, 279. 

 ^ Marks, H. K., Z. Immunitatsjorsch. Orig., 1911, xi, 18. 

 * Mutermilch Compt. Rend Soc de Biol., 1911, Ixx, 577. 

 ^ Leschly, W., Z. Immimitdtsforsch. Orig., 1916, xxv, 44. 

 « Brand, O., Berl. Klin. Woch., 1907, xliv, 1075. 



^ Ehrlich, R. and Morgenroth, J., Berl. Klin. Woch., 1899, xxxvi, 481. 

 8 Ehrlich, R., and Sachs, H., Berl. Klin. Woch., 1902, xxxix, 297. 



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