HuGRO, IL-8 and gamma-IP-10 belong to a recently described superfamily of genes encoding a group of cytokines with inflammatory, growth regulating and/or leukocyte chemotactic properties (chemokines). We studied huGRO, IL-8 and gamma-IP-10 gene expression in unstimulated and stimulated (TNF alpha, INF gamma, TNF alpha + IFN gamma, IL-1 beta, PMA and LPS) normal human keratinocytes by Northern blot analysis. The mRNA for none of the three chemokines was detectable in unstimulated keratinocytes, but considerably elevated levels of huGRO and IL-8 mRNA, but not of gamma-IP-10 mRNA, were found in the presence of cycloheximide, indicating that huGRO and IL-8 mRNA, but not gamma-IP-10 mRNA, are constitutively produced. gamma-IP-10 mRNA was exclusively induced by IFN gamma, with a strong and transient rise between 8 and 18 h, and superinduced by the combination of IFN gamma and TNF alpha, indicating marked synergism. Both huGRO and IL-8 mRNA were induced by TNF alpha and PMA (a strong and transient rise between 2 and 8 h), but not by IFN gamma or LPS. The combination of TNF alpha and IFN gamma did not show a synergistic effect. In addition, IL-1 beta transiently upregulated huGRO mRNA but failed to induce IL-8 mRNA. Using specific oligonucleotides for alpha, beta and gamma huGRO, TNF alpha was found to induce all three forms, alpha and beta to an equal extent and gamma to a lesser extent.(ABSTRACT TRUNCATED AT 250 WORDS)