A Proposed Mouse Protection Unit for Anti-Meningococcus Serum

Abstract

The use of mucin for the enhancement of the infectivity of meningococci in the mouse has now been studied for over 5 years. 1 The first use of this technic in the titration of the protective action of sera was reported over 3 years ago. 2 Subsequently, other laboratories have reported the titration of protective antibodies in antimeningococcus serum and in each case the details of technic employed have varied slightly or markedly. 3 4 5 6 7 8 9 In order that values obtained in the titration of antimeningococcus sera in various laboratories may be comparable, that figures obtained by the use of the test may have a wide application, and that sera used for therapeusis may be studied on a basis which allows quantitative comparison, it has seemed advisable to set up and distribute a tentative standard polyvalent serum as a control and to assign to this serum certain values so that other sera may be referred to it quantitatively. It has also seemed desirable that a uniform technic for performing the mouse protection test be used.

In order to obtain a polyvalent serum and data for this purpose, a serum (of which ample amounts were available) was selected because it resembled closely the older control serum M 18 in its protective capacity and other immunological reactions, This has been designated M 19. Repeated estimations of antibody nitrogen for Group I∗ were carried out with this serum and it was determined that the serum contained 0.65 mg of antispecific polysaccharide nitrogen 10 per cubic centimeter. It has been shown 8 that the Group I protective power of antimeningococcus serum probably parallels the type-specific antibody nitrogen content. This has also been found to be the case with antipneumococcus sera. In the latter case 1.00 mg of antibody nitrogen is found to be equivalent to approximately 1000 protective units, a convenient figure.