This communication describes methodologies for isolation and culture of alveolar macrophages from humans and murine models for experimental purposes.
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Method Article
Isolation and In Vitro Culture of Murine and Human Alveolar Macrophages
In This Article
Summary
Abstract
Alveolar macrophages are terminally differentiated, lung-resident macrophages of prenatal origin. Alveolar macrophages are unique in their long life and their important role in lung development and function, as well as their lung-localized responses to infection and inflammation. To date, no unified method for identification, isolation, and handling of alveolar macrophages from humans and mice exists. Such a method is needed for studies on these important innate immune cells in various experimental settings. The method described here, which can be easily adopted by any laboratory, is a simplified approach to harvesting alveolar macrophages from bronchoalveolar lavage fluid or from lung tissue and maintaining them in vitro. Because alveolar macrophages primarily occur as adherent cells in the alveoli, the focus of this method is on dislodging them prior to harvest and identification. The lung is a highly vascularized organ, and various cell types of myeloid and lymphoid origin inhabit, interact, and are influenced by the lung microenvironment. By using the set of surface markers described here, researchers can easily and unambiguously distinguish alveolar macrophages from other leukocytes, and purify them for downstream applications. The culture method developed herein supports both human and mouse alveolar macrophages for in vitro growth, and is compatible with cellular and molecular studies.
Introduction
The lung microenvironment is a uniquely complex ecosystem with an elaborate air conduit and vasculature. The inhaled air travels through the trachea and through numerous branches of bronchi and bronchioles before reaching the alveoli, where the blood-air gas exchange occurs. Due to direct interaction with the atmosphere, the respiratory surface requires protection from the potentially harmful effects of airborne particles and pollutants. A number of physical, chemical, and immunologic barriers protect the lungs. Notably, deployment of phagocytes at the respiratory surface serves an important first-line defense system. Alveolar macrophages (AMs) are one type of lung-re....
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Protocol
All methods described here have been approved by the Institutional Animal Care and Use Committee (IACUC) and the Institutional Review Board (IRB) at St Joseph's Hospital and Medical Center.
1. Isolation of AMs from Murine Bronchoalveolar Lavage (BAL) Fluid
- Anaesthetize an eight-week-old C57BL/6 mouse with ketamine (87.5 mg/kg body weight) and xylazine (12.5 mg/kg body weight) cocktail via an intraperitoneal injection. Proceed when mouse attains surgical anesthesia with loss of reflexes and relaxation of muscles.
- Place the mouse on a dissection surface with the ventral side facing up. Apply ophthalmic vet ointment o....
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Results
The flow cytometric approach to identify mouse AMs is shown in Figure 1. This includes analysis of a minimum set of surface markers necessary in distinguishing AMs from other lung-resident or lung-infiltrating phagocytes. Differential analysis is required to positively identify AMs from interstitial macrophages, dendritic cells, neutrophils, monocytes, and monocyte-derived pulmonary macrophages that occur in lungs. The following scheme of surface markers can .......
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Discussion
AMs are long-living lung-resident macrophages that populate the lungs beginning at birth and enduring over the entire life span26. Their roles in pulmonary physiology7 and pathology12 and their potential to predict of pulmonary autoimmunity24 have been recognized. Because AMs have a long-term presence in lungs11,27 and because they are involved in activation and progre.......
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Disclosures
The authors have no conflicts of interest to declare.
Acknowledgements
We thank Clare Prendergast for assistance with editing the manuscript. DKN is supported by a research grant (#2095) from the Flinn Foundation and TM is supported by grants from National Institutes of Health (R01HL056643 and R01HL092514). DKN developed the methods, designed the study and wrote the manuscript; OM assisted with animal studies and clinical sample procurement; SB assisted with Flow cytometric analysis and cell sorting; TM supervised the studies and reviewed the manuscript.
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Materials
| Name | Company | Catalog Number | Comments |
|---|---|---|---|
| Non-enzymatic cell dissociating solution | Millipore-Sigma | C5789 | |
| Puralube Vet Ointment | Dechra | 620300 | |
| 22G Catheter | Terumo Medical Products | SR-OX2225CA | |
| 4-0 Non-absorbable silk braided suture | Kent Scientific | SUT-15-2 | |
| Dulbecco’s phosphate buffered saline | Corning | 21-031-CM | |
| Mouse Fc block | BD Biosciences | 553142 | |
| Lysis buffer (PureLink RNA Kit) | Thermo Fisher Scientific | 12183018A | |
| b-Mercaptoethanol | Millipore-Sigma | M6250 | |
| FACSAria II cell sorter | BD Biosciences | 644832 | |
| Ketamine (Ketathesia) | Henry Schein | 56344 | |
| Xylazine (AnaSed) | Akorn | 139-236 | |
| RPMI 1640 | Corning | 10-040-CM | |
| DMEM | Corning | 10-017-CM | |
| Liberase TL | Millipore-Sigma | 5401020001 | |
| DNase I | Millipore-Sigma | AMPD1-1KT | |
| 100μm cell strainer | Corning | 352360 | |
| Human Fc block | BD Biosciences | 564220 | |
| EDTA | Corning | 46-034-CI | |
| Countess II Automated Cell Counter | Thermo Fisher Scientific | AMQAX1000 | |
| Trypan Blue Solution | Thermo Fisher Scientific | 15250061 | |
| HEPES | Corning | 25-060-CI | |
| Fetal Bovine Serum | Atlanta Biologicals | S11150H | |
| L-929 cell line | American Type Culture Collection | ATCC, CCL-1 | |
| Penicillin/Streptomycin | Corning | 30-002-CI | |
| Sodium Pyruvate | Corning | 25-000-CI | |
| T25 Tissue culture flask | Thermo Fisher Scientific | 156367 | |
| 60 mm culture dish | Millipore-Sigma | CLS3261 | |
| 15 mL Conical tube | Corning | 352097 | |
| 50 mL Conical tube | Corning | 352098 | |
| LSRFortessa cell analyzer | BD Biosciences | 657669 | |
| FlowJo | FlowJo | v10.4 | Analysis Software |
| Anti-CD45 (Mouse) | Biolegend | 147709 | Clone I3/2.3, FITC conjugated |
| Anti-CD11b (Mouse) | Biolegend | 101228 | Clone M1/70, PerCP/Cy5.5 conjugated |
| Anti-CD11c (Mouse) | BD Biosciences | 565452 | Clone N418, BV 421 conjugated |
| Anti-I-Ab (Mouse) | Biolegend | 116420 | Clone AF6-120.1, PE/Cy7 conjugated |
| Anti-Siglec-F (Mouse) | BD Biosciences | 562757 | Clone E50-2440, PE-CF594 conjugated |
| Anti-Siglec-H (Mouse) | Biolegend | 129605 | Clone 551, PE conjugated |
| Anti-F4/80 (Mouse) | Biolegend | 123118 | Clone BM8, APC/Cy7 conjugated |
| Anti-Ly-6C (Mouse) | Biolegend | 128035 | Clone HK1.4, BV605 conjugated |
| Anti-CD64 (Mouse) | Biolegend | 139311 | Clone X54-5/7.1, BV711 conjugated |
| Anti-CD24 (Mouse) | BD Biosciences | 563115 | Clone M1/69, BV510 conjugated |
| Anti-CD103 (Mouse) | BD Biosciences | 745305 | Clone OX-62, BV650 conjugated |
| Anti-CD317 (Mouse) | Biolegend | 127015 | Clone 927, APC conjugated |
| Anti-CXCR1 (Mouse) | Biolegend | 149029 | Clone SA011F11, BV785 conjugated |
| Anti-CD45 (Human) | Biolegend | 304017 | Clone HI30, AF488 conjugated |
| Anti-CD11b (Human) | Biolegend | 101216 | Clone M1/70, PE/Cy7 conjugated |
| Anti-HLA-DR (Human) | Biolegend | 307618 | Clone L243, APC/Cy7 conjugated |
| Anti-CD169 (Human) | Biolegend | 346008 | Clone 7-239, APC conjugated |
| Anti-CD206 (Human) | Biolegend | 321106 | Clone 15-2, PE conjugated |
| Anti-CD163 (Human) | Biolegend | 333612 | Clone GHI/61, BV421 conjugated |
References
- Westphalen, K., et al. Sessile alveolar macrophages communicate with alveolar epithelium to modulate immunity. Nature. 506 (7489), 503-506 (2014).
- Guilliams, M., et al. Alveolar macrophages devel....
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