Phase I studies of C. parvum given intravenously: effects of dexamethasone on its biologic and toxic properties.

Three biologic effects were clearly associated with C. parvum infusions: a) granulocytosis with lymphomonocytopenia, b) increase in responsiveness to phytohemmagglutinin and c) increase of specific antibodies to C. parvum antigens. Addition of dexamethasone moderately altered the kinetics of leukocyte changes without affecting other properties. Side effects after intravenous administration of C. parvum (2.5 mg/m2) consisted primarily of chills and fever which lasted for periods of 6-24 hours. Side effects occurred in 77% of the infusions. Addition of dexamethasone (4 mg IVP) reduced significantly the frequency (only 22% of patients) and intensity (fever 102 F and chills for only 30-60 minutes) of side effects. Clearly, dexamethasone of the dosage employed did not abrogate C. parvum effects while reducing significantly its toxic properties.