146 



Scientific Proceedings (53). 



94 (790) 



Note on the relation of alexin to thrombin. 



By Theo. C. Burnett (by invitation). 



[From the Rudolph Spreckels Physiological Laboratory of the 

 University of California.] 



The publishing of negative results is, as a rule, a questionable 

 proceeding. Occasionally however, a negative result may have 

 a positive bearing upon a subject, of more or less value, in which 

 case the objection does not hold. It is for this reason I present 

 the following note. 



In reviewing the subject of coagulation some time ago, I was 

 struck by a certain similarity between thrombin and alexin. 

 Both are inactivated by a temperature of 56 degrees; both are 

 derived from leucocytes; 1 thrombin consists of thrombokinase and 

 calcium, while alexin consists of two parts, as is well known. It 

 occurred to me that there might be a closer relation between the 

 two; that they might in fact, be identical. It has probably 

 occurred to many another, but in a hasty glance over the literature, 

 I can find no mention of it. At first sight the idea seems absurd, 

 for alexin is contained in serum that has been collected over a 

 clot, and hence contains no thrombin. The alexic potency of a 

 serum, however, increases by standing for some hours in contact 

 with the clot, and it is conceivable that during that time thrombin 

 is excreted by the leucocytes, but is not apparent because of the 

 absence of fibrinogen wherewith to combine. Having occasion to 

 prepare some thrombin for another purpose, I determined to test 

 the matter. 



The immune serum used was rabbit serum immunized against 

 ox corpuscles. Tested with guinea-pig serum it had a potency 

 of 1-800. (Ox blood was used on account of the ease with which 

 material could be obtained at any time.) Most of the experiments 

 were carried out with a 1-100 dilution, although similar results 

 were obtained with higher dilutions. 



The thrombin was prepared by Howell's method 2 and gave a 



1 It is generally conceded now that thrombin is derived from the platelets. 

 1 Howell, W. H., Am. Jour. Physiol., Vol. 26, 1910, p. 453. 



