CXCL12 and infection: In addition, the delayed infection of the ILN, spleen, and the GI tract in CCR7-/- mice indicates that in the absence of CCR7, signaling via other receptor/chemokine pairs such as CCR8:CCL1/CCL8, CXCR4/CXCL12, CX3CR1/CX3CL1 and/or S1PR: S1P might direct cell migration and thus allow for Chlamydia systemic dissemination, albeit less efficiently.