ATTEMPTS AT ANALYSIS OF TOXICITY OF PERTUSSIS VACCINE III. EFFECTS OF ENDOTOXIN ON LEUKOCYTOSIS IN MICE DUE TO LYMPHOCYTOSIS-PROMOTING FACTOR AND REFERENCE PREPARATIONS FOR DETERMINATION OF LYMPHOCYTOSIS-PROMOTING FACTOR

Abstract
The effect of bacterial endotoxin on the change in peripheral leukocyte population in mice due to the lymphocytosis-promoting factor (LPF) was investigated. Endotoxin affected the total leukocyte count and the leukocyte proportions at any observation time. The coefficient and the intercept of regression of the leukocytic response on dose of LPF were modified by endotoxin. Therefore, in a valid biological assay for LPF using the peripheral leukocyte count as a response, a common reference preparation available for any test materials, irrespective of presence or absence of endotoxin, will be impracticable. Two reference preparations were tentatively established, a vaccine and an LPF preparation containing little endotoxin. A unitage of LPF activity was assigned to each reference preparation. An LPF material to be tested for its possible effects on the lymphatic tissues or the RES should be free from endotoxin.