Heparin as an Anticoagulant in the Brucella Phagocytic Index Test

Abstract

In a previous publication, 1 the application of the Brucella phagocytic index test to the study of epidemiology of undulant fever was discussed. Tests carried out on over 1,000 people seemed to indicate that the test was of value in the detection of passed, latent and present infections with the Brucella organisms.

When the same technic was applied to the natural hosts, goats and cattle, the differences between the normal and the infected animals were not striking. Although positive indices were obtained in some of the smaller laboratory rodents, in larger animals the phagocytic activity of the leucocytes, despite the presence of Brucella organisms in the tissues, was either absent or very low. The indices of the infected or immunized animals were, however, consistently high, when, instead of whole citrated blood, the sedimented cells thoroughly washed and resuspended in Locke's gelatin solution were mixed with fresh serum and a bacterial suspension in equal quantities. From these observations it was concluded that the citrate solution was toxic for the leucocytes of certain herbivorous animals or inhibited in some way the phagocytic activity of the granulocytes. Since the washed cell method was too time-consuming for routine use, it was decided to search for an anticoagulant that would be more suitable for the purpose. Several were tried, including sodium oxalate, sodium fluoride, “Liquoide”, amniotic fluid, and heparin. Heparin∗ was found to be far the most effective. A 1-1,000 dilution of heparin in saline (1 drop of blood to 1 drop of heparin solution) for human blood and 0.2 cc. of a 1:200 dilution for cattle and goats was employed, the test being conducted otherwise exactly as with citrate.

In Table I the significant data are summarized. A comparison of the indices determined on the leucocytes of citrated and heparinized blood clearly indicates that cattle as well as goats yield much higher indices when heparin is employed as an anticoagulant. In a group of recently infected cows the average index of the granulocytes in citrated blood was 1.6 and in heparin-treated blood it was 13.6.