Identification of interleukin 1 alpha produced by the 3B6 human EBV-B cell line.

: We have previously described a novel protein, derived from the 3B6 EBV B-cell line which apparently displayed IL-1 bioactivity. We report here that the protein previously characterized is not a new species of IL-1. Indeed, we have now been able to clone and express a cDNA which identifies this protein as human thioredoxin, an intracellular dithiol oxydo-reductase enzyme. Thioredoxin however, is not a lymphokine and in particular does not possess IL-1 activity. Our earlier data can be explained in the light of recent findings, reported herein, indicating that IL-1 alpha is produced by the 3B6 line as assessed by antibody inhibition studies and IL-1 alpha mRNA expression. Thus our original protein preparation actually contained traces of IL-1 alpha, which was responsible for the biologic activities and thioredoxin.