The presence of interleukin-2 receptor alpha in the serum of colorectal cancer patients is unlikely to result only from T cell up-regulation

It is unclear whether the presence of interleukin-2 soluble receptor alpha (IL-2 sRalpha) in the serum of colorectal cancer patients is solely due to T cell activation. In this study, we therefore investigated whether T cell activation, indicated by the up-regulation of the CD25 and HLA-DR markers, or cell-mediated immunity (CMI) were associated with increased serum levels of IL-2 sRalpha in patients with advanced colorectal carcinoma. The levels of serum IL-2 sRalpha and the proportion of T cells expressing HLA-DR (DR(+) T cells) were measured as markers for chronic activation. CMI was assessed by delayed-type hypersensitivity reaction (DTH) to intradermal injections of recall antigens. Eighty-seven colorectal liver metastases (CLM) patients and 23 'cancer-free' control subjects were studied. DR(+) T cells were found to be more prevalent ( P