Pulmonary macrophages, Diff-Quick
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Pulmonary macrophages are tissue macrophages that engulf micro-organisms and debris within the alveolar space. In congestive heart failure, the debris often includes red blood cells (RBCs). When the hemoglobin is broken down within the cell, hemosiderin pigment remains. These macrophages are then called "heart-failure cells". Like all other cells of monocyte/macrophage linage, their major function is presentation of antigen to T cells. These macrophages were obtained by broncho-alveolar lavage (i.e, through an endoscope). They have the characteristics of most macrophages, a small nucleus and a large amount of cytoplasm.