A method for the detection of erythrocyte-bound interleukin-8 in humans during interleukin-1 immunotherapy.

Interleukin-8 (IL-8) has been recently shown to bind to human erythrocytes with high affinity and is therefore potentially difficult to detect in serum or plasma. IL-8 is transiently elevated in the serum of baboons after the administration of interleukin-1 alpha (IL-1 alpha). The objective of this study was to investigate whether IL-8 can be detected in the plasma or in detergent-lysed erythrocytes from cancer patients undergoing treatment with IL-1 alpha. Using a specific radioimmunoassay (RIA), plasma IL-8 was detected within 1-2 h after the first IL-1 alpha infusion. Thereafter, the levels declined rapidly and after 4-8 h were undetectable. Erythrocyte-bound IL-8 was detectable 1-2 h after the increase in plasma levels. The erythrocyte-bound IL-8 levels were higher than those measured in plasma and remained elevated long after the plasma levels had become undetectable. Erythrocyte membranes accounted for all of the erythrocyte-associated IL-8, as IL-8 was undetectable in the cytosol after erythrocyte lysis. The assay used in these studies detects IL-8 in erythrocyte lysates when it cannot be measured in plasma and may therefore be useful in monitoring IL-8 production in vivo.