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June 28, 1952


Author Affiliations

Frederick, Md.
From the Chemical Corps Biological Laboratories, Camp Detrick.

JAMA. 1952;149(9):809-813. doi:10.1001/jama.1952.02930260011004

During experiments concerned with natural resistance it was found that the blood of dogs, animals with low susceptibility, had intense bactericidal action for Brucella, requiring the combined action of leukocytes and plasma.1 To study the role of phagocytosis in this reaction, it was necessary to distinguish between phagocytic and opsonic activity. From studies on phagocytosis, a method evolved that measured the opsonin titer of liquids.2

Studies were carried out with the blood of dogs and then with human beings concerned with these studies, the latter having negative skin tests and agglutinin titers for brucellergin and Brucella, respectively; however, the opsonin content of the blood of the human beings increased during the course of the studies. Furthermore, the opsonin content of the blood of dogs that had never been in the laboratory was lower than that of those employed for Brucella studies.2 Suspecting that the opsonin titers of