Abstract
Interpretation of percentages obtained in phagocytic tests on patients undergoing treatment (in this instance, diathermy) is made difficult by the facts that the total leukocyte count in such patients varies and the concentration of leukocytes used in the test sensibly affects the percent of phagocytosis. To evaluate this variation it was necessary to devise a phagocytic test in which the leukocytes would be subjected to the least possible manipulation. Two cc. of heparinized salt solution (containing 1 mg. of heparin per cc. of 0.9% NaCl) are put into a test tube and about 9 cc. of blood added. In a second dry tube about 1 cc. of blood is collected and allowed to clot. The heparinized sample is centrifuged and the cells are washed once with salt solution, then divided into 2 portions. Portion A remains untreated, portion B is deleukocyted by a modification of the method of Fleming. 1 A U-tube is prepared of glass tubing with a constriction in one limb into which absorbent cotton is packed tightly. The other limb is connected to the vacuum apparatus, a little salt solution is drawn through the cotton, and finally the cell suspension B is sucked through 3 or 4 times and is thus rid of most of its leukocytes. By mixing this filtered suspension in various proportions with portion A, a series of blood samples is obtained having the same number of erythrocytes but different numbers of leukocytes.
Phagocytic tests were then run. Two volumes of the blood containing leukocytes are drawn into a bent capillary pipette, followed by one volume each of a suspension of a heat-killed culture of streptococcus and serum from the clotted blood. These substances are mixed by drawing back and forth in the pipette, the end of which is then sealed in the flame and the mixture incubated at 37°C. for 15 minutes.
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