Corticosteroid can alter antigen expression on alveolar macrophages

Abstract

SUMMARY 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 > 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.