LEUKEMIA INHIBITORY FACTOR IS EXPRESSED BY NORMAL HUMAN KERATINOCYTESIN-VITRO AND IN-VIVO

Leukaemia inhibitory factor (LIF) is a pleotropic cytokine, regulating differentiation, cell growth, cachexia and inflammation, Using the re verse transcription-polymerase chain reaction (RT-PCR) we found that, in culture, normal human keratinocytes (KC) expressed mRNA transcripts for both LIF and the LIF receptor, In the conditioned medium (CM), co nstitutive LIF protein production was barely detectable but stimulatio n of KC with 10 ng/ml of either interleukin (IL)-1 alpha, or IL-8, for 24 h, resulted in small but significant increases (P < 0.05) in LIF p rotein, as measured by enzgme-linked immunosorbent assay, After cultur e in media containing 1.5 mmol/l calcium, a time-dependent increase in LIF mRNA was seen up to 72 h (an 8.5-fold increase), over levels in c ells cultured in 0.05 mmol/l calcium, A large increase in LIF protein in the CM (from 1.15+/-0.15 pg/ml to 178.7+/-75.7 pg/ml) was seen 72 h after a switch to media containing 1.5 mmol/l calcium (P = 0.05), Twe nty-four hours after stimulation of human KC in culture with 10 ng/ml recombinant LIF, a twofold increase in both IL-1 alpha and IL-8 protei n in the CM (P < 0.05) was observed, In normal human scalp and foreski n, the epidermis was shown to contain LIF protein by immunostaining, L IF staining was found throughout the epidermis, and in the cells of th e outer layer of the root sheath, Thus, KC synthesize LIF in vitro and in vivo.