Clinical Immunology - Macrophages

Blood monocytes

In general, where do macrophages come from?

No; blood monocytes are needed for an efficient response

In response to inflammation, resident tissue macrophages can proliferate. Can these cells manage infection on their own?

They become macrophages

When blood monocytes enter the inflamed tissue, what happens?

Early recognition of pathogens and tissue damage, promoting inflammation, phagocytosis, and tissue repair and wound healing

What are the four major functions associated with macrophages?

Pattern recognition receptors

Macrophages recognize pathogens and tissue damage via?

To promote inflammation

Macropahges produce cytokines and chemokines for what purpose?

Promotion of angiogenesis and fibrosis

How do macrophages initiate wound repair and healing?

TLRs, RIG-I receptors, NOD-like receptors, lectin, lectins, mannose receptors

What are some of the pattern recognition receptors associated with macrophages?

IL8

Which chemokine is responsible for recruiting neutrophils?

True

True or False: Macrophages are the major phagocytic cell in tissues

Activation, chemotaxis, adherence, ingestion, and destruction

What are the steps of phagocytosis?

PAMPs and DAMPs

Which main categories of molecules can activate macrophages?

Neutrophils at the site of inflammation produce macrophage chemoattractants

How are macrophages attracted to the site of inflammation?

Receptors

Macrophages adhere to microbes via different types of?

The microbe becomes enclosed in a vacuole known as a phagosome, which fuses to the lysosome to form a phagolysosome

Once the microbe is bound to the macrophage, what occurs?

Within the phagolysosome

Destruction of the microbe occurs where?

False

True or False: Like neutrophils, macrophages do not have the ability to undertake repeated phagocytosis

Acidification, metal toxicity or starvation, and proteases

What are some of the non-oxidative mechanisms used for the destruction of pathogens?

Lactoferrin

Which substance binds iron for metal starvation?

Nitric oxide synthase; induces nitric oxide production from arginine

When macrophages are activated, iNOS expression is induced. What is this and what does it do?

M1 - classically activated; M2 - alternatively activated

What are the two types of activation?

Antimicrobial killing, proinflammatory

M1 macrophages have what functions?

M2 macrophages

Which macrophages are responsible for tissue remodeling and repair?

IL-4, IL-13, and IL-10

Which cytokines cause M2 activation?

Via iNOS or arginase

How do macrophages switch from their M1 to M2 phenotype?

Apoptotic neutrophils suppress further neutrophil recruitment and are phagocytized by macrophages

How does the process of tissue repair begin?

Break down, remodel

M2 macrophages can both ___ and ___ tissue

Granuloma formation

Chronic macrophage stimulation due to persistence of antigen leads to?

MHC molecules on their cell surface

Antigen presentation refers to the process by which cells display antigens bound to ___

MHCII

Professional antigen presenting cells display antigens bound to?

Professional antigen presenting cells

Cells which are involved in the differentiation and activation of various immune cells are?

All nucleated cells

Which cells can present antigen on MHCI?

Dendritic cells, B cells, and macrophages

What are the main professional antigen presenting cells?

Activate T cells

Antigen presentation via dendritic cells has what effect?

Enhances their microbicidal activity

Antigen presentation by macrophages has what effect?

Cells containing intracellular antigens can be killed by immune effector cells

MHCI presentation has what effect?