Abstract
(1) The spleen is essential for the Factor VIII elevations observed after adrenalin infusion and other acutely stressful stimuli. The spleen appears to be capable of either storing and releasing Factor VIII, or of effecting release of Factor VIII from some other site.
(2) The Factor VIII elevations do not appear to be dependent on the concomitant platelet rises that occur after adrenalin.
(3) An inverse relationship between platelet and Factor VIII levels is frequently found in pathological states associated with chronic thrombocytopenia or thrombocytosis.
(4) Platelet transfusions do not appear to influence Factor VIII levels.
(5) In vitro attempts to demontrate adsorption of Factor VIII by platelets or elution of Factor VIII from platelets in the presence and absence of adrenalin were not successful.