Modulation of IL-8 receptor expression on purified human T lymphocytes is associated with changed chemotactic responses to IL-8

Interleukin-8 is a member of the chemokine superfamily and is a major mediator of acute inflammation. Although IL-8 has been reported by some laboratories also to be a chemoattractant for T lymphocytes, this has been difficult to confirm and remains a controversial issue. By using freshly purified human T cells (90-95% CD³⁺), we could demonstrate consistent directional migration of T cells to recombinant human IL-8. IL-8 was as potent as RANTES, MIP1α, and MIP1β in inducing T cell chemotaxis. Highly purified T cells, however, incubated at 37°C for more than 12 h or cultured overnight with anti-CD3 antibody cross-linked to plastic dishes, showed a markedly reduced capacity to migrate in response to IL-8. This was associated with a decrease in binding of radioiodinated IL-8 to T cells. Northern blot and polymerase chain reaction analyses showed that freshly purified T cells expressed mRNA for both IL-8 receptor type A and type B. Steady-state levels of mRNA for the IL-8RA and IL-8RB genes were also reduced by incubation of the cells with or without anti-CD3 for 12 h at 37°C. These results indicate that T cells are indeed one of the target cell populations for IL-8. The regulation of IL-8 receptor expression on T lymphocytes may contribute to the pathophysiological role of IL-8 in inducing the homing and infiltration of T cells.