Histamine in human breast cancer.

Histamine inhibits lymphocyte function in vitro at concentrations of greater than 10(-6) mol/l. The aim of this study was to determine whether histamine concentrations in breast cancers were sufficient to produce an immunological effect. Tumour and adjacent normal breast content of histamine was measured using a radioenzymatic assay in 29 patients having surgery for breast cancer. The median content of histamine in breast cancer tissue was 5.4 (range 0.9-27.3) microg/g (median concentration 4.5 x 10(-5) mol/l), and was significantly greater than that in adjacent breast tissue (P = 0.007). The concentration of histamine in breast cancer was sufficient to inhibit lymphocyte function and could be locally immunosuppressive.