Abstract
In a previous paper, 1 a method of preparing immune sera in guinea pigs for the human blood property Rh was given. The technic has been found to be improved by the following modification.
Full-grown guinea pigs are injected intraperitoneally 5 times at intervals of about 5 days, with each dose consisting of the washed cells from 2 cc of blood from rhesus monkeys. A week after the last injection the animals are bled. Satisfactory sera may be pooled and preserved with merthiolate 1:5000.
For the test, the sera (inactivated, if fresh) were diluted 10 times with saline and absorbed for one hour at room temperature with one-tenth volume of blood sediment containing equal parts of A1 and B blood. Whether the absorbing blood is Rh-positive or Rh-negative seems to make little or no difference, showing that the antibodies responsible for the distinctive reaction are not readily absorbed by Rh-positive blood and have less affinity for human cells than the other antibodies present in the serum. The tests are carried outand read by inspection of the sediment, as previously described. The tests could also conveniently be carried out with dilutions (e.g. 1:4) of the absorbed fluid, and in fact in this way the difference in appearance between positive and negative sediments may even be more conspicuous.
The advantage of this modification, entailing longer continued immunization, appears to be the higher proportion of usable sera obtained. Probably owing to the greater content of species (as well as Rh) antibodies, the procedure of simple dilution was found tobe inadequate, and absorption was necessary in order to obtain a sharp distinction between positive and negative bloods.
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