IL-1 beta and IL-6 in mouse parotid acinar cells: characterization of synthesis, storage, and release

Synthesis, storage, and secretion of the proinflammatory cytokine interleukin-1 beta (IL-1 beta) and the anti-inflammatory cytokine IL-6 have not been established in normal exocrine gland secretory cells. Parotid glands and isolated acinar cells prepared from BALB/c mice were homogenized for RNA isolation and reverse transcription-polymerase chain reaction (RT-PCR). IL-1 beta and IL-6 enzyme-linked immunosorbent assays (ELISAs) were done on supernatants prepared from mouse parotid acinar cell (MPAC) preparations unstimulated or stimulated between 0 and 10 min with 10(-5) M norepinephrine at 37 degrees C. MPACs were fixed in paraformaldehyde, frozen sectioned for light and electron microscopy, and labeled with antibodies to IL-1 beta and IL-6. Mouse specific riboprobes to IL-1 and IL-6 were used for in situ hybridization. RT-PCR yielded the expected IL-1 (336-bp) and IL-6 (614-bp) mRNA products. By ELISA, stimulated MPACs showed a significant increase in IL-1 beta (P < 0.03) and IL-6 (P < 0.01) release into supernatants by 10 min that paralleled the time course of amylase release. In situ hybridization showed the presence of transcripts for IL-1 and IL-6 in glandular epithelial cells. Gold-labeled IL-1 beta and IL-6 were significantly higher (P < 0.01) in granules than in the nucleus and cytoplasm. This study shows that MPACs synthesize IL-1 beta and IL-6 and release these cytokines from their granules after alpha- and beta-adrenergic stimulation.