Immunology and Infection
Published: August 7th, 2021
This protocol describes the process for obtaining human macrophages from monocytes for infection with Leishmania braziliensis. It also allows researchers to evaluate infection rate and parasite viability, ROS production by fluorescence microscopy, and the production of inflammatory mediators in culture supernatants to investigate macrophage response to infection.
Macrophages are multifunctional cells essential to the immune system function, and the primary host cell in Leishmania braziliensis (Lb) infection. These cells are specialized in microorganism recognition and phagocytosis, but also activate other immune cells and present antigens, as well as promote inflammation and tissue repair. Here, we describe a protocol to obtain mononuclear cells from peripheral blood (PBMC) of healthy donors to separate monocytes that then differentiate into macrophages. These cells can then be infected in vitro at different Lb concentrations to evaluate the ability to control infection, as well as evaluate host cell immune response, which can be measured by several methods. PBMCs were first isolated by centrifuging with Ficoll-Hypaque gradient and then plated to allow monocytes to adhere to culture plates; non-adherent cells were removed by washing. Next, adherent cells were cultured with macrophage-colony stimulating factor (M-CSF) for 7 days to induce macrophage differentiation. We suggest plating 2 x 106 cells per well on 24-well plates in order to obtain 2 x 105 macrophages. Fully differentiated macrophages can then be infected with Lb for 4 or 24 hours. This protocol results in a significant percentage of infected cells, which can be assessed by optical or fluorescence microscopy. In addition to infection index, parasite load can be measured by counting the numbers of parasites inside each cell. Further molecular and functional assays can also be performed in culture supernatants or within the macrophages themselves, which allows this protocol to be applied in a variety of contexts and also adapted to other intracellular parasite species.
The intracellular protozoan parasite of the genus Leishmania is the causative agent of a neglected disease complex known as leishmaniasis1. These tropical diseases have a wide range of clinical manifestations that can range from skin lesions to complications arising from the visceral form of the disease, which can be fatal if not treated. Cutaneous leishmaniasis (CL) is the most frequent form of leishmaniasis and is characterized by a single or few ulcerated skin lesions with exacerbated chronic inflammation2. The development of disease is dependent on the Leishmania species, in addition to a combinatio....
The Institutional Review Board for Ethics in Human Research at the Gonçalo Moniz Institute (Oswaldo Cruz Foundation-IGM-FIOCRUZ, Salvador, Bahia-Brazil), approved this study (protocol number: CAAE 95996618.8.0000.0040).
1. Isolation of human PBMCs
The comprehension of parasites and host cells interaction is crucial to elucidate mechanisms involved in the pathogenesis of several diseases. Although cultured human cells are less used due to limitations of cell culture compared to cell lineages, the protocol presented herein shows a robust and reproducible differentiation of human macrophages. This protocol enables the analysis of several aspects of the immune response and cell biology, from the production of inflammatory mediators up to the susceptibility of an infec.......
The protocol presented herein for human monocytes differentiation into macrophages followed by the infection with two strains of L. braziliensis allows the evaluation of several aspects of parasite-cell interaction. These tools can be crucial to elucidate unanswered questions about CL. With the establishment of this protocol, our group was able to uncover some aspects of the immune response of macrophages obtained from individuals with diabetes and CL14.
This work was supported by Fundação de Amparo à Pesquisa do Estado da Bahia (FAPESB) under Grant number PET0009/2016 and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brazil (CAPES) under Finance Code 001.....
|AlamarBlue Cell Viability Reagent
|Cell Culture Flask 25 cm²
|CellROX Green Reagent
|Coverslip circles 13 mm
|Disposable support for blood collection
|Eclipse blood collection needle 21 g x 1.25 in
|Falcon Conical Tubes, 15 mL
|Falcon Conical Tubes, 50 mL
|Fetal Bovine Serum
|Glass slide 25,4x76,2mm
|Human IL-6 ELISA Kit
|Human M-CSF Recombinant Protein
|Human TNF-a ELISA Kit
|Leukotriene B4 ELISA Kit
|Phosphate Buffered Saline pH 7.2 (10x)
|Plasma tube, 158 USP units of sodium heparin (spray coated)
|Quick H&E Staining Kit (Hematoxylin and Eosin)
|RPMI 1640 Medium
|Schneider's Insect Medium
|Tissue Culture 24-wells Plate
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