Human keratinocytes in vitro have receptors for leukotriene B4

We have demonstrated a high-affinity binding site for leukotriene B4 (LTB4) on human epidermal keratinocytes in vitro. In substrate saturation studies, one population of binding sites with a dissociation constant (Kd) of 1.03 +/- 0.3 nM and a maximal binding capacity (Bmax) of 148.2 +/- 45.3 fmol/mg protein could be demonstrated. On average 5,500 binding sites were found on individual keratinocytes in culture. The affinity constant of this binding site correlates well with previous reports on the proliferative effect of LTB4 on keratinocytes in vitro. These findings confirm that LTB4 may in part be responsible for epidermal hyperproliferation in inflammatory skin diseases.