Standardization of the Anti-viral Content of Immune Globulin from Placental Extract

Abstract

It is now accepted that preparations of globulin from human placentas can modify or prevent measles in humans. 1 In addition to its content of anti-measles antibody indicated clinically, the placental extract has been shown to contain diphtheria and scarlet fever antitoxins and antipoliomyelitis antibodies. 2 At the present time the diphtheria antitoxin content is widely employed as a means of determining the potency of different preparations; and, despite the fact that the antitoxic and antiviral antibodies are distributed differently in the placental extract, with the former entirely in the pseudoglobulin and the latter distributed in several fractions, 3 it has been stated that the determination of the diphtheria antitoxin titer is satisfactory as a basis for determining the anti-measles potency of different preparations.

Ideally, each preparation should be standardized for its anti-measles antibody content. Since, however, the lack of a susceptible animal other than the monkey renders such standardization at present impossible, it would seem advisable to titrate the different preparations for some other antiviral antibody. Poliomyelitis virus neutralization tests have been successfully carried out 2 but here again no routine standardization is possible. Antibodies for other viruses are to be found in human sera, however, and those against swine influenza are probably as widespread as those against measles. These influenza antibodies are readily titratable in the albino Swiss mouse and different preparations of placental extract can be tested for this antiviral antibody. Such tests are reported below.

Lungs of mice, sacrificed while moribund from swine influenza infection∗ after intranasal inoculation and showing extensive lung involvement, were used after being preserved in 50% glycerine from 1-5 days. Such lungs were ground in sufficient tyrodes to give a 1/50 dilution of the wet weight of the lung.