Normal and sarcoid alveolar macrophages differ in their ability to present antigen and to cluster with autologous lymphocytes

Abstract

SUMMARYHuman bronchoalveolar macrophages from normal individuals function poorly as accessory cells for the presentation of common reeall antigens. In sarcoidosis, alveolar macrophages (AM) are reported to be effective accessory cells for the presentation of such antigens. In this study normal and sarcoid AM were compared with blood monoeytes for their ability to act as accessory eells in presenting tuberculin purified protein derivative (PPD) and streptokinase-streptodornase (SKSD) to autologous T lymphocytes, or to form spontaneous, antigen-or mitogen-induced clusters with the T cells. When compared to autologous monocytes, normal AM failed to present the two recall antigens effectively. Likewise normal AM formed very few clusters with T lymphocytes when compared to monocytes, even in the presence of antigens or the mitogen phytohaemagglutinin (PHA), In contrast, sareoid AM presented both antigens as effectively, and were equally effective as monocytes in forming clusters with T lymphocytes, spontaneously and in further response to antigen or mitogen. The results suggest that in sarcoidosis enhanced accessory cell function and enhanced cluster formation may be related features of bronchoalveolar macrophage populations.

Role of lung macrophages on susceptibility to respiratory infection following short-term moderate exercise training

“…Macrophages also have the ability to produce chemokines, which can recruit and activate additional cell types to combat viral infection (37). In addition to playing a role in innate immunity, macrophages are able to process and present antigen to T lymphocytes (33); however, numerous studies have demonstrated that alveolar macrophages are poor antigen presenters compared with dentritic cells (5,15). It is possible, however, that alveolar macrophages may influence the degree of activity of dendritic cells by releasing cytokines (24).…”

Increased CD11/CD18 expression on peripheral blood leucocytes of patients with sarcoidosis

“…Before their migration to sites of active disease [7,8] sarcoid mononuclear cells must adhere to the endothelium of capillaries. Once within tissues, sarcoid lymphocytes and monocytes have been shown to associate closely [9,10], an interaction which may favour both granuloma formation [11] and the enhanced lymphoproliferation which has been reported by cells retrieved from tissues such as the lung [10,12].…”

Enrichment and characterization of dendritic cells from human bronchoalveolar lavages

“…Infiammatory processes may alter the antigen-presenting capacity of AM, as was implied for AM from patients with pulmonary sarcoidosis, which have increased antigen-presenting capacity [1,4,8]. Poulter [15] reported that within the BAL of patients with pulmonary sarcoidosis increased numbers of RFD1+/RFD7" cells, a dendritic cell-associated phenotype, were found.…”

“…The majority of studies with human bronchoalveolar lavage (BAL) cells of normal subjects showed that alveolar macrophages (AM) generally function poorly as antigen-presenting cells in T cell responses compared with blood monocytes or macrophages from other tissues [1][2][3][4], although a high percentage of human AM express HLA-D region antigens [5][6][7][8]. The AM may even suppress T cell responses, as shown particularly at high AM/T cell ratios [2,[9][10][11][12].…”