IL-1β is the major form of IL-1 produced by mononuclear phagocytes. To evaluate the possible mechanisms underlying the observation that mature populations of human mononuclear phagocytes as alveolar macrophages are relatively poor IL-1 producers compared with blood monocytes, the expression of the IL-1β gene mRNA transcripts was evaluated in LPS-stimulated autologous blood monocytes and alveolar macrophages by using a IL-1β cDNA probe. Although Northern analysis demonstrated that stimulated monocytes and alveolar macrophages both express 1.8-kb IL-1β mRNA transcripts, cytoplasmic dot blot analysis showed that the total IL-1β mRNA content in alveolar macrophages was only 38 ± 5% of that in blood monocytes. In situ hybridization with antisense and sense IL-1β RNA probes demonstrated that whereas most of stimulated blood monocytes contained IL-1β mRNA transcripts, a significant proportion of autologous alveolar macrophages stimulated in an identical fashion did not express the IL-1β gene. Within 4 h after LPS stimulation, IL-1β mRNA transcripts were detected in 81 ± 6% monocytes, whereas only 16 ± 9% of alveolar macrophages were positive, and by 18 h this had increased only to 43 ± 15%. Quantification of the size distribution of the IL-1β mRNA expressing mononuclear phagocytes demonstrated that, among the population of alveolar macrophages, the cells expressing this gene were not confined to those that were 'monocyte-like'. These observations demonstrate that there is a heterogeneity among population of mononuclear phagocytes in their ability to express the gene for IL-1β, which could explain the differences observed in IL-1 production.
|Number of pages||8|
|Journal||Journal of Immunology|
|Publication status||Published - 1 Jan 1988|
ASJC Scopus subject areas
- Immunology and Allergy