IL-8 can be secreted by any cells with toll-like receptors that are involved in the innate immune response and has been demonstrated to be a signatory chemokine of CR2+ naive T cells also known as recent thymic emigrants). Usually, it is the macrophages that see an antigen first, and thus are the first cells to release IL-8 to recruit other cells. Both monomer and homodimer forms of IL-8 have been reported to be potent inducers of the chemokine receptors CXCR1 and CXCR2. The homodimer is more potent, but methylation of Leu25 can block the activity of homodimers.