Induction of a 26-kDa-protein MRNA in Human Cells Treated with an Interleukin-1-related, Leukocyte-derived Factor

A human-leukocyte-derived antiviral protein (22-kDa factor), known to be an inducer of interferon-beta (IFN-beta) in fibroblastoid cells, and to be closely related to interleukin-1 (IL-1), was shown to likewise act as inducer of the mRNA of a 26-kDa secreted protein. This protein was first described as the gene product of an mRNA that is co-induced with the mRNA of IFN-beta by superinduction of fibroblasts (treatment with dsRNA and cycloheximide). Subsequently it was shown to be induced by treatment with cycloheximide only. The 22-kDa factor induced high levels of the 26-kDa-protein mRNA and low levels of IFN-beta mRNA. Addition of cycloheximide to the 22-kDa factor resulted in further significant increases in mRNA levels for both the 26-kDa-protein and IFN-beta. These observations add to the evidence already available that transcription of the genes for IFN-beta and the 26-kDa-protein are differently regulated. The observation that a factor that belongs to the IL-1 family induces the 26-kDa-protein suggest that the latter plays a role as an intermediary or effector molecule in inflammatory or immunoregulatory processes.