Effect of the Transcription Factor GATA‐2 on Phagocytic Activity of Alveolar Macrophages from Pneumocystis carinii‐Infected Hosts

Abstract

Experiments were performed to determine whether this defect is specific for P. carinii organisms. The results showed that these macrophages were unable to phagocytose both P. carinii organisms and fluorescein isothiocyanate (FITC)-conjugated latex beads, indicating that alveolar macrophages from P. carinii-infected hosts have a general defect in phagocytosis. To determine whether this defect correlates with the recently discovered down-regulation of the GATA-2 transcription factor gene during P. carinii infection, alveolar macrophages from dexamethasone-suppressed or healthy rats were treated with anti-GATA-2 oligonucleotides and then assayed for phagocytosis. Aliquots of the alveolar macrophages were also treated with the sense oligonucleotides as the control. Cells treated with the antisense oligonucleotides were found to have a 46% reduction in phagocytosis of P. carinii organisms and a 65% reduction in phagocytosis of FITC-latex beads compared to those treated with the sense oligonucleotides. To determine whether the defect in phagocytosis in alveolar macrophages from P. carinii-infected hosts can be corrected by overexpression of GATA-2, a plasmid containing the rat GATA-2 gene in the sense orientation driven by the cytomegalovirus (CMV) promoter was introduced into alveolar macrophages from P. carinii-infected rats. Aliquots of the same cells transfected with a plasmid containing GATA-2 in the antisense orientation relative to the CMV promoter served as the control. Alveolar macrophages treated with the sense GATA-2 expression construct were found to increase their phagocytic activity by 66% in phagocytosis of P. carinii organisms and by 280% in phagocytosis of FITC-latex beads compared to those that received the antisense GATA-2 construct. The results of this study indicate that GATA-2 plays an important role in the regulation of phagocytosis in alveolar macrophages during P. carinii infection.

Inhibition of Macrophage Complement Receptor CRIg by TRIM72 Polarizes Innate Immunity of the Lung

“…To dissect the physiological role of the interaction between TRIM72 and CRIg, we first conducted experiments to examine AM phagocytosis. Indiscriminate opsonized phagocytosis was examined using non-heat-inactivated FBS-coated FITC beads (26). Our results show that, in the absence of TRIM72, both the phagocytic index and percentage of phagocytic cells were significantly increased as compared with the WT.…”

“…AMs containing fluorescent beads/particles were counted to determine % phagocytic cells. FITC 1 AMs were also quantified by flow cytometry and counted for phagocytic indexes (number of ingested beads/macrophages) (26).…”

Platelet microparticles reprogram macrophage gene expression and function

“…These results prompted us to assess if platelet MPs influenced the phagocytic capacity of primary human macrophages by using FITC-labelled latex micro-beads, which are commonly used in phagocytosis assays involving professional phagocytes, such as macrophages (35,36). Confocal microscopy analysis unveiled a marked increase in the phagocytic capacity of macrophages upon a 48-h exposure to platelet MPs (▶ Figure 7 A, centre panel), compared to macrophages that were never exposed to MPs (▶ Figure 7 A, upper panel).…”

Allogeneic hematopoietic cell transplantation in patients with GATA2 deficiency—a case report and comprehensive review of the literature

“…Increased susceptibility to infections with intracellular pathogens is likely a consequence of macrophage/monocyte dysfunction. Likewise, reduced phagocytic activity of pulmonary alveolar macrophages resulting from GATA2 deficiency contributes to the common occurrence of pulmonary alveolar proteinosis (PAP) that can be observed in patients with GATA2 deficiency [14]. The high frequency of human papilloma virus (HPV) and other viral infections results most likely from the profound absence of NK cells [7].…”