Twenty-three lots of commercial preparations of human γ-globulin (GG) derived from placental extracts were titrated in HeLa cell cultures for antibodies neutralizing measles virus, with cytopathology serving as an end point indicator. Titers of the various lots ranged between 10-2.70 and 10-3.30/0.1 ml of GG, giving a 4-fold difference between the lowest and highest titer. Repeated titrations of two “low” and two “high” titered lots indicated this difference to be highly significant.
Fifteen of the 23 lots were also titrated for the three types of poliomyelitis antibodies by the metabolism-inhibition test in the presence of monkey kidney cells. Titers ranged between 10-3.91 and 10-4.39/0.25 ml of GG for type I, between 10-4.09 and 10-4.70 for type II, and 10-3.79 and 10-4.39 for type III, which parallels the seroepidemiological pattern of the types of poliomyelitis in the U.S.A. The variation between the highest and lowest poliomyelitis titers obtained was similar to that for measles, being 3-fold for type I and 4-fold for types II and III.
The application of these findings to the eventual establishment of minimum requirements for the release of commercial lots of GG is discussed.