Adhesion molecule expression and leucocyte trafficking following immunotherapy with recombinant interleukin-2

The relevant anti-tumour mechanisms of recombinant interleukin-2 (rIL-2) in vivo are unclear but an influx of T-lymphocytes and macrophages has been noted in regressing lesions. One of the dose limiting toxicities of rIL-2 is the development of a capillary leak syndrome attributed to widespread endothelial activation. Changes in expression of endothelial and leucocyte-associated adhesion molecules were assessed in tumour and uninvolved skin in patients with metastatic breast cancer receiving rIL-2. Increased expression of intracellular adhesion molecule-1, its leucocyte-associated ligand, leucocyte function associated molecule-1, vascular cell adhesion molecule and its ligand, very late after activation antigen-4 as well as members of the selectin family of adhesion molecules, were noted in uninvolved skin following rIL-2. Expression of these adhesion molecules was noted in tumour stroma before rIL-2 but little change was observed following rIL-2 infusion. An influx of monocytes and T-lymphocytes (expressing the IL-2 receptor and of the memory subtype) and a lower number of neutrophils was noted in uninvolved skin following rIL-2. Although monocytes and T-lymphocytes were present in tumour stroma before rIL-2 no changes were observed following infusion. The changes noted in the dermis contrast with those seen at tumour sites and may partly explain the low therapeutic index of rIL-2.