Basics Flashcards
Elie Metchnikoff
First coined the name “macrophage” to describe large mononuclear phagocytic cells he observed in tissues in 1882.
Mononuclear phagocyte system
A term introduced by van furth that encompasses myeloid immune cells other than polymorphonuclear granulocytes and initially included monocytes and macrophages, and then, following their discovery, dendritic cells.
Dogma created in 1968 that the homeostasis of tissue-resident macrophages relies on the constant recruitment of blood monocytes i.e. The two related cell types arise from a continuum of differentiation.
Van Furth’s mononuclear phagocyte system
Argument against mononuclear phagocyte system
1) monocytes do not substantially contribute to most tissue macrophage compartments in the steady state or during times of inflammation
2) adult tissue macrophages are derived from embryonic precursors that seed the tissues before birth
3) tissue macrophages an maintain themselves in adults by self renewal
(Based mostly on murine studies)
microRNA
A class of short endogenous non-coding RNA’s that modulate the proteome through binding to complementary mRNAs and repressing translational initiation or inducing mRNA degradation. This post-transcriptional regulation of gene expression depends on an imperfect match of short seed sequences with their target mRNA and hence each miRNA has potential to suppress multiple targets.
Classical Dendritic Cells
A term introduced by Ralph Steinman that should be reserved for short lived, FLT3 (fms-like tyrosine kinase 3 or CD135) ligand dependent cells with migratory capability and a potential to efficiently stimulate naive T cells
Macrophages and DC precursor
A bone marrow resident LIN-CD117+CD135+ clonotypic precursor with plasmacytoid dendritic (pDC), classical (cDC) and monocyte potential.
Common monocyte progenitor (CMoP)
A bone marrow resident LIN-CD117+ precursor with monocyte potential that is the direct progeny of macrophage and dendritic cell precursors (MDPs)
Necrosis
A form of uncontrolled cell death caused by factors that are external to the cell or tissue-such as infection, toxins or trauma, that result in the unregulated destruction of cellular components
Anticipatory Inflammation
The finding in mice that the abundance of circulating LY6C^hi monocytes is under circadian control, which might have evolved to prepare the organism for insults.
C3a
Induces:
Mast cell degranulation
Chemotaxis
C5a
Induces:
Chemotaxis
Smooth muscle contractions (broncospasms)
Vascular permeability
Mast cell degranulation (histamine & tnf)
Time monocytes are in blood
10-20 hrs
Origin of monocytes
Bone marrow–> myeloid blast–>monocyte–>blood–>tissue
Steps to diapedesis
Injury:
- bacteria enter
- Tissue Macrophages phagocytose bacteria and secrete cytokines
- —tnf, il beta, inf gamma,il8
- mast cells degranulate and produce histamine and thrombin
- endothelial integrin expression
Rolling (selectins)
Adhesion (Integrins)
Binding
Diapedesis
