Issues with Immunity and Autoimmunity

Question 1

Allergy and the different types of immune reaction

Answer 1

Two types of immunity – innate (humoral) immunity, that which we are born with and acquired immunity which we develop over time and exposure to antigens.

Two pathways by which immunity is mediated – cell mediated involving T lymphocytes and antibody mediated involving B lymphocytes

Question 2

Anaphylaxis/ angioedema

Answer 2

Acute, potentially fatal, multiorgan system reaction
Caused by the release of chemical mediators from mast cells and basophils.

Physiologically the body’s responses are - smooth muscle spasm in the respiratory and gastrointestinal (GI) tracts- Vasodilation and increased vascular permeability leading to - hypotension, cardiac arrhythmias, syncope, shock- Increased mucous secretion, increased bronchial smooth muscle tone, airway oedema

Question 3

Antigen

Answer 3

any substance (such as an immunogen or a hapten) foreign to the body that evokes an immune response either alone or after forming a complex with a larger molecule (such as a protein) and that is capable of binding with a product (such as an antibody or T cell) of the immune response

Question 4

Antibody

Answer 4

any of a large number of proteins of high molecular weight that are produced normally by specialized B cells after stimulation by an antigen and act specifically against the antigen in an immune response, that are produced abnormally by some cancer cells, and that typically consist of four subunits including two heavy chains and two light chains— called also immunoglobulin’

Question 5

Enzyme

Answer 5

any of numerous complex proteins that are produced by living cells and catalyse specific biochemical reactions at body temperatures

Question 6

Psoriasis

Answer 6

Red raised plaques with thick white/silver scaly surface on knees, elbows, trunk and scalp, nails and less often skin flexures (often external vs eczema which is often inside creases, etc.) Increased dermal fibroblasts. Key inflammatory cell involved is the neutrophil polymorph

Question 7

Sarcoidosis

Answer 7

Chronic granulomatous disease of unknown origin
Many tissues infiltrated by non-caseating granulomas of histiocytic giant cells. Granulomas resemble those of TB
Main systems affected are lymphoreticular, lungs, skin eyes and brain

Question 8

Type 1 diabetes –insulin dependent

Answer 8

Genetic predisposition, pancreatic pathology
Viral infection e.g. mumps, Epstein-Barr
Dietary factors e.g. cows milk in early infancy
Covid-19 has been shown to both cause diabetes and cause increased mortality in diabetics

Question 9

IBS Crohn’s disease and ulcerative colitis

Answer 9

Ulcerative colitis only affects the colon; Crohn’s disease can affect any portion of the GIT
UC –inflammation only penetrates mucosa, starts at rectum, confluent ulceration * Crohn’s – inflammation of all bowel wall layers, submucosal oedema, deep discrete ulcers

Question 10

Multiple sclerosis

Answer 10

Activated T-lymphocytes cross the blood-brain barrier and trigger CNS inflammation
Reaction with myelin derived antigens
Demyelination of CNS (brain and spinal cord), leaving plaques

Question 11

Hashimoto’s thyroiditis - hypothyroid presentation

Answer 11

Autoimmune inflammation of the thyroid
Potential genetic or environmental factors Including radiation exposure
Tends to affect patients with the HLA-DR5 antigen
Anti-microsomal and anti-thyroid antibodies present
Progression through hyperthyroid symptoms to an increasing hypothyroidism

Question 12

Grave’s disease- hyperthyroid presentation

Answer 12

Aetiology and Pathophysiology
As with Hashimoto’s, an autoimmune inflammation of the thyroid
Caused by a specific IgG antibody acting on thyroid follicle cells,
Stimulation of constant hyperplasia and TH secretion (pituitary control overridden) Always secreting, no control)

Question 13

Pernicious anaemia

Answer 13

Severe vitamin B12 deficiency resulting in megaloblastic anaemia
Causes can include- inadequate dietary intake- atrophy of gastric mucosa- abnormal intrinsic factor- bacterial overgrowth in intestine
Enzyme dysfunction leads to megaloblastic changes in cells

Question 14

Myasthenia gravis

Answer 14

Condition has no definitive cause
IgG antibody to acetylcholine receptors is specific
Neuromuscular transmission is blocked – damage to acetylcholine receptors prevents conduction of nerve signal carried by acetylcholine across the synaptic cleft

Question 15

Polymyalgia Rheumatica

Answer 15

Systematic T cell and macrophage activation
Potential viral activation of monocytes although not confirmed
Inflammation starts in synovium and bursae
Specifically a condition in elderly populations
Existing giant cell arteritis is a risk factor