Differential regulation of interleukin-1 gene expression in human CD3- large granular lymphocytes

Our laboratory analyzed the expression of lymphokine and cytokine mRNA in CD3- peripheral blood large granular lymphocytes (LGL). Herein we present evidence that this subset of lymphocytes can synthesize IL-1 beta mRNA constitutively and that the cytoplasmic mRNA levels of IL-1 beta can be increased rapidly by interleukin (IL)-2. IL-1 alpha mRNA is expressed constitutively very infrequently and increases in IL-1 alpha mRNA are seen only after prolonged incubation with IL-2. Furthermore, IL-1 activity could not be detected in LGL culture supernatants, indicating that other processes may be involved in releasing biologically active IL-1 from LGL. In addition, MAb to the p75 IL-2 receptor on LGL abrogated IL-2 induction of IL-1 beta mRNA, suggesting that IL-2 signaling via the p75 IL-2 receptor induced IL-1 beta gene expression in LGL. Since, in contrast to T cells, LGL are capable of mediating effector functions without prior stimulation, they are said to be already "primed" for response. Overall, these data suggest that constitutive lymphokine gene expression may be involved in the in vivo priming of LGL.