Two monoclonal antibodies, anti-IL8R1 and anti-IL8R2, raised against both interleukin 8 receptors (IL-8R) of human neutrophils, IL-8R1 and IL- 8R2, were used to study individual receptor functions after stimulation with IL-8, GROα, or NAP-2. Efficacy and selectivity of the antibodies were tested in Jurkat cells transfected with cDNA coding for one or the other receptor. The binding of 125I-labeled IL-8 and IL-8-induced changes of the cytosolic free Ca2+ concentration were inhibited by anti-lL8Rl in cells expressing IL-8R1 and by anti-IL8R2 in cells expressing IL-8R2. In human neutrophils, release of elastase was observed after stimulation with IL-8 or GROα. The response to IL-8 was inhibited slightly by anti-IL8R1 and more substantially when both monoclonal antibodies were present, while the response to GROα was inhibited by anti-IL8R2 but was not affected by anti-IL8R1. These results indicate that both IL-8 receptors can signal independently for granule enzyme release. Superoxide production, a measure of the respiratory burst, was obtained with increasing concentrations of IL-8 with maximum effects at 25 to 50 nM, but no response was observed upon challenge with GROα or NAP-2 up to 1000 nM. The superoxide production induced by IL-8 was inhibited by anti- IL8R1, but was not affected by anti-IL8R2. Stimulation of neutrophils with IL-8, in contrast to GROα or NAP-2, also elicited phospholipase D activity. The effect of IL-8 was again inhibited by anti-IL8R1 but not by anti-IL8R2, indicating that this response, like the respiratory burst, was mediated by IL-8R1. Taken together, our results show that IL-8R1 and IL-8R2 are functionally different. Responses, such as cytosolic free Ca2+ changes and the release of granule enzymes, are mediated through both receptors, whereas the respiratory burst and the activation of phospholipase D depend exclusively on stimulation through IL-8R1.
|Number of pages||5|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|Publication status||Published - 26 Jul 1996|
- enzyme release
- neutrophil activation
- respiratory burst