Note on the relation of alexin to thrombin

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.