Placental Immunity. 2. Comparison of Maternal Circulating Blood Immunity with that of Placental Fluid

In their study of the prophylactic value in measles of the globulin extracted from the human placenta McKhann and Chu 1 raised the question of the source of these antibodies. They believed that besides maternal and fetal blood there were possibly antibodies originating in the placental tissue as such.

The demonstration by various authors that the titre of cord blood and maternal circulating blood for diphtheria antitoxin, scarlet fever antitoxin, and poliomyelitis virus neutralizing substance are alike in most instances, suggests the direct transplacental transmission of antibodies from the mother to the child.

We 2 reported that the globulin extracted from immune adult males′ blood in the same manner as suggested by McKhann for placenta was equally effective in measles prophylaxis as the blood itself. In attempting to explain the striking results of McKhann and coworkers we suggested that possibly all of the extracellular placental fluid may be comparable to blood serum in its antibody content. In the course of several studies on placental immunity we obtained some evidence which seems to bear out this suggestion.

15–20 cc. of blood was drawn from a superficial vein of the mother at the time of expulsion of the placenta. This blood was permitted to clot, and the diphtheria antitoxic titre of the serum was measured by the toxic neutralizing test. The placenta plus what blood and fluid dropped into the receptacle with it was collected under sterile conditions. The fluid was decanted. The placenta was cut up into many small sections and squeezed in a simple orange hand press.

The fluid so obtained plus the blood which was decanted were mixed and measured, then centrifuged for 15 minutes under high speed. The sanguinous supernatant fluid was measured and its diphtheria antitoxic titre determined.