HECA-452(-CELLS MIGRATE THROUGH SUPERFICIAL VASCULAR PLEXUS BUT NOT THROUGH DEEP VASCULAR PLEXUS ENDOTHELIUM() T)

The skin is nourished by two interconnected vascular systems, the supe rficial vascular plexus coursing just beneath the epidermis and the de ep vascular plexus located above the subcutaneous tissue. Skin inflamm atory T cells in diseases, such as psoriasis or dermatitis, strikingly aim for the superficial vascular plexus without involving the deep va scular plexus, and the infiltrating T cells bear a distinct phenotype expressing the cutaneous lymphocyte-associated antigen, which is recog nized by mAb HECA-452, We wanted to know whether HECA-452(+) lymphocyt es indeed are able to distinguish between superficial and deep vascula r plexus homing sites, Employing the hu-SCID mouse model grafted with human skin and human T cells, as described previously, we developed a new skin-grafting strategy providing superficial and deep vascular ple xus skin specimens placed separately onto the same mouse. Fourteen day s after allogeneic human T cell grafting, both human skin sites were d ensely infiltrated by human T cells, but only T cells within the super ficial vascular plexus, but not within the deep vascular plexus, expre ssed the cutaneous lymphocyte-associated antigen. IL-2 and IFN-gamma e xpression and allogeneic vessel destruction were present within both s uperficial and deep vascular plexus skin, This model provides direct e vidence that expression of a specific homing receptor is indeed able t o direct lymphocyte traffic, not only to a distinct organ but also to a distinct vascular bed within one organ.