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Corticosteroid can alter antigen expression on alveolar macrophages
1Department of Clinical Immunology, Royal Free Hospital School of Medicine, London, England, UK.
Insights
Corticosteroid Budesonide directly impacts alveolar macrophages, altering their immune cell markers. This suggests steroids may directly influence lung immune responses by modifying macrophage function.
Area of Science:
- Immunology
- Pulmonology
- Cell Biology
Background:
- Alveolar macrophages are crucial for lung immune responses.
- Corticosteroids are commonly used to treat inflammatory lung diseases.
- Understanding the direct effects of corticosteroids on macrophages is important.
Purpose of the Study:
- To investigate the direct effects of Budesonide on human alveolar macrophage subsets.
- To determine if Budesonide alters the expression of specific macrophage surface antigens.
Main Methods:
- Broncho-alveolar lavage (BAL) was performed on healthy volunteers.
- Alveolar macrophages were cultured for 24 and 48 hours with or without Budesonide.
- Immunocytochemical analysis was used to assess the expression of RFD1, RFD7, CD68, Fc(IgG), and HLA-DR.
Main Results:
- Budesonide treatment decreased the proportion of RFD1+ (antigen-presenting) macrophages and increased RFD7+ (mature phagocyte) macrophages.
- These changes were specific, as Budesonide did not affect CD68 or Fc(IgG) receptor expression.
- HLA-DR expression was downregulated after 24 hours of Budesonide exposure.
Conclusions:
- Budesonide directly affects alveolar macrophage phenotype and antigen expression.
- These steroid-induced changes suggest a direct role for Budesonide in modulating lung immune responses via macrophage function.
Abstract:
Normal healthy volunteers underwent broncho-alveolar lavage and the cells obtained were cultured for 24 h and 48 h, either alone or in the presence of the corticosteroid, Budesonide. Cell differentials were all normal, the lavages containing greater than 90% alveolar macrophages. Cytospins of these cells were prepared before and after culture. The cytospins were subjected to immunocytochemical analysis using a panel of MoAbs selected to identify subsets of macrophages and functionally relevant surface antigens. In particular, the expression of RFD1 (antigen presenting cell marker) and RFD7 (mature phagocyte marker) were studied. Before culture, BAL macrophages could be divided into two subsets. Of the cells, 39.3% were RFD1+ and 47.2% were RFD7+. Culture with Budesonide was seen to reduce the proportions of RFD1+ cells to 38% while increasing the RFD7+ population to 69% of total. These changes were relatively specific as Budesonide failed to alter the expression of CD68 or Fc(IgG) receptors. Down-regulation of HLA-DR expression was seen, however, after 24 h contact with Budesonide. As these changes could have functional significance, these data support the hypothesis that steroids may have direct effects on the role of alveolar macrophages in immune responses in the lung.