Red cell sequestration during high dose intravenous immunoglobulin in idiopathic thrombocytopenic purpura.

The cellular interactions involved in the platelet response after immunoglobulin infusion in acute and chronic idiopathic thrombocytopenic purpura (ITP) are unknown. There have been a number of theories including the competitive inhibition of platelet-binding to macrophages by the preferential sequestration of immunoglobulin coated red cells. We report a study to examine this hypothesis. Adult acute and chronic patients were given infusions of immunoglobulin at a rate of 0.4 g/kg body weight, daily for 5 days. Serum haptoglobin, lactate dehydrogenase and the absolute reticulocyte counts were monitored and no significant change in any value was seen during the period of study. A red cell survival was performed on four of the patients and no increase in the rate of red cell clearance occurred during the infusion period. We conclude from this that in these patients no significant degree of haemolysis was provoked by the infusion although this does not preclude this as a mechanism of action in some individuals.