Correlation of interleukin 6 with interleukin 1α in human mammary tumours, but not with oestrogen receptor expression

The authors hypothesized that IL-6 production by breast tumour tissues would correlate with OR-positivity, as only those tumours that contain oestrogen receptors (OR) and use oestrogen as a mitogen would benefit from locally increased oestrogen. IL-6 increases the activity of the 17β-oxidoreductase, which converts oestrone to oestradiol, a process that may contribute to the increased concentration of oestrogen around breast tumours. IL-1α upregulates IL-6 production; therefore, the correlation between IL-1α and IL-6 immunoreactivity and OR-positivity in paraffin-embedded human breast tumours was further investigated. The results indicate IL-6 immunoreactivity in 40 of 66 paraffin embedded breast tumour specimens, a finding which did not correlate with the clinical evaluation of oestrogen receptor positivity (P = 0.32 by Fisher's exact test). However, there was a correlation between IL-6 and IL-1α immunoreactivity (P < 0.05). To study an in vitro model for this phenomenon, the IL-6 immunoreactivity in available cell lines was tested. Surprisingly, no production of IL-6 protein or mRNA could be detected in any of the cell lines, and this did not change with IL-1α stimulation. Therefore, none of the cell lines apparently reflected the immunological potential observed in the majority of surgical specimens.