5. Immunopathology Flashcards
The innate immune system is the .... It involves souble factors, such as ...; and cellular components, such as ..., ..., ..., ... and ....
The adaptive immune system is a relatively .... However it has increased .... It involves cellular components, such as ..., ..., ..., .... Innate and adaptive immune systems overlap such that ... and ... are cytotoxic lymphocytes that straddle the interface of innate and adaptive immunity.
The innate immune system is the first line of defence against infections. It involves souble factors, such as complement proteins; and cellular components, such as granulocytes (basophils, eosinophils and neutrophils), mast cells, macrophages, dendritic cells and natural killer cells.
The adaptive immune system is a relatively slower defence. However it has increased antigenic specificity & memory. It involves cellular components, such as antibodies, B cells, CD4+, CD8+ T lymphocytes. Innate and adaptive immune systems overlap such that NKT cells and gamma-delta T cells are cytotoxic lymphocytes that straddle the interface of innate and adaptive immunity.
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Lymphatic vessels are ... intraocularly and are generally .... These are major factor in the eye’s .... Introcularly, lymphatics can be found in 7 structures: ..., ..., ..., ..., ..., ..., and ....
Lymphatic vessels are rare intraocularly and are generally scarce in the eye and orbit. These are major factor in the eye’s immune privilege. Introcularly, lymphatics can be found in 7 structures: conjunctiva, limbus, lacrimal gland, dural sheath of optic nerve, eyelids, connective tissues of EOM, and choroid.
Peripheral organs of the lymphatic system is called MALTs = .... B cells and T cells migrate to MALTS, as well as .... Once B cells in MALT encounters their complementary antigen, they will .... MALTs are found in the ..., ..., ... and .... MALTs in the ... consist mainly of ... plasma cells, which are associated with .... MALTs in ... predominantly consist of ... and ....
Peripheral organs of the lymphatic system is called MALTs = mucosa-associated lymphoid tissues. B cells and T cells migrate to MALTS, as well as peripheral/ secondary lymphatic organs e.g. spleen, lymph nodes. Once B cells in MALT encounters their complementary antigen, they will proliferate, migrate and become antibody-secreting plasma cells. MALTs are found in the lacrimal gland, conjunctiva, canaliculae and lacrimal mucosa. MALTs in the lacrimal gland consist mainly of IgA-positive plasma cells, which are associated with grouped and individually patrolling T-cells. MALTs in canaliculae and lacrimal mucosa predominantly consist of T cells and macrophages.
What is immune privilege?
Immune privilege are sites in the body where foreign tissue grafts can survive for extended or indefinite periods of time, whereas similar grafts placed at conventional body sites are acutely rejected.
How do we know that there is intraocular immune privilege?
There is no excessive immune response within blood-ocular barriers.
• Success of corneal transplantation without foreign tissue rejection
• Unrestricted growth of allogenic tumour cells intraocularly
• Aqueous and vitreous fluids inhibit inflammatory cells in vitro
Intraocular immune privilege is achieved by having an efficeint ... and no .... There are high levels of ... within the eye, which aids in .... This is expressed by ...; ... helps inhibit ... and promote .... There is also active ..., such as ..., where eye-derived antigens elicit ..., thus .... There is expression of ... in the cornea, iris and CB epithelium, which ....
Intraocular immune privilege is achieved by having an efficeint blood-retinal barrier and no efferent lymphatics. There are high levels of TGF-b2 within the eye, which aids in inhibiting immune responses from T cells. This is expressed by pigmented cells e.g. RPE, PE of ciliary body and iris; alpha-MSH helps inhibit macrophage activation and promote production of anti-inflammatory factors. There is also active regulation of immune responses, such as anterior chamber acquired immune deviation (ACAID), where eye-derived antigens elicit T-reg skewed response, thus DTH (delayed hypersensitivity) is suppressed. There is expression of Fas ligand in the cornea, iris and CB epithelium, which actively induces infiltrating Fas+T cells to undergo apoptosis.
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How do follicles appear clinically?
Raised gelatinous lesions of upper and lower tarsal and bulbar conjunctiva. They are surrounding blood vessels. No damaging collateral response.
What is the pathogenic causes of prominent follicles?
Secondary to viral or chlamydia infections → in response to antigens; Sensitivity to topical medication
Conjunctival follicles are ..., defined .... They are found in .... By selectively staining for ..., we can reveal the .... ... can be seen surrounding the .... Follicles are therefore ....
Conjunctival follicles are flat, defined accumulations of lymphocytes. They are found in normal conjunctiva. By selectively staining for B cells, we can reveal the germinal centre. T cells (CD3+) can be seen surrounding the germinal centre. Follicles are therefore MALTs (mucosa-associated lymphoid tissue).
How does conjunctival follicles responds to antigen exposure?
Conjunctival follicles undergoes hyperplasia. There is proliferation of appropriate lymphocyte population to produce memory cells and plasma cells. Plasma cells then migrate to diffuse layer and release antibodies. This also induces memory cells to proliferate. This ultimately causes the enlargement of follicles.
Although the cornea has ... due to being .... However, there is still a chance of ... with ... tissue. During ..., there will be huge infiltration of ..., ... into the donor cells. There have been studies that show ... and ... increase the likelihood of ... via ....
Although the cornea has immune privilege due to being avascular. However, there is still a chance of corneal graft rejection with non-MHC matched tissue. During graft rejection, there will be huge infiltration of macrophages, CD4+ and CD8+ T cells into the donor cells. There have been studies that show corneal neovascularisation and lymphangiogenesis increase the likelihood of graft rejection via reflex arc to lymph nodes.
What are the 4 conditions that can manifest from autoimmune responses in the eye?
• Uveitis
• Episcleritis
• Scleritis
• Dry eyes disease
In px with rheumatoid arthritis, there is characteristic... of the iris in autoimmune .... There are also cells in the ...and also presence of ... adhered to the corneal .... ... may also be present, which are modified .... There could also be scleritis, which is characterised by ..., which is driven by ... activity.
In px with rheumatoid arthritis, there is characteristiclymphocytic and plasma cell infiltration of the iris in autoimmune anterior uveitis. There are also cells in the anterior chamberand also presence of keratin precipitates adhered to the corneal endothelium. Russell bodies may also be present, which are modified plasma cells, containing excessive immunoglobulin. There could also be scleritis, which is characterised by granulomatous cell formation around necrotic collagen, which is driven by T cell and macrophage activity.
