SAQ

Question 1

1a) What are the implications and potentials of this disease for the patient?

Answer 1

• Inflammation and damage to the filtering part of the kidneys
• Quick/slow onset
• Toxins/metabolic waste/excess fluids are NOT properly filtered (build up, causing swelling and fatigue)
• Haematuria (loss of RBC, due to inflammatory response)
• Azotemia (too much waste product in blood, i.e., nitrogen, creatine)
• Proteinuria (loss of proteins in blood)
• High blood pressure (due to inflammation/scarring)
• Dialysis may be needed (to clean blood and remove excess fluid/toxins)
• Kidney failure requires transplant
• May result in end-stage renal disease (ESRD)

Question 2

1b) What would a positive result for the congo red method mean for the patient?

Answer 2

• Congo Red differentiates between amyloidosis and fibrillary glomerulonrphritis (FGN)
• They usually share similar electron microscope signatures and similar clinical signs
• Positive result indicates amyloidosis
• Detects the amyloid structure of protein aggregates
• Blue-green birefringence and bright orange areas of amyloid deposition

Question 3

1c) What is the principle of the PAS method?

Answer 3

• A histochemical reaction
• Demonstrates polysaccharides, glycogen, etc. in carbohydrates
• Periodic acid oxidases carbohydrates to release aldehyde, making it an oxidised compound which fixes to the colourless Schiff’s reagent
• Magenta colour localized at site of aldehyde formation

Question 4

1d) How would the presence of “malignant hypertension” show as in the tissue?

Answer 4

• Visible areas of thrombosis (blood clots in vessels) and necrosis
• Glomerular lesions
• Smaller glomeruli, varying degrees of hyalinization
• Tubular atrophy (injury with thickened tubular basement membrane)
• Periglomerular fibrosis (hardening/scarring of tissue)

Question 5

1e) What type of glomerulonephritis is suggested in the photographic results above?

Answer 5

• Crescentic/rapidly progressing glomerulonrphritis
• Renal biopsy PAS shows: formation of crescent, composed of parietal epithelial cells, macrophages, fibrin
• Fibrin found between proliferated cells
• Compressed capillary loops
• Segmental fibrinoid necrosis of glomerular tuffs
• > 50% crescent formation in glomeruli

Question 6

1f) What potential treatment and lifestyle changes would the patient need to consider with the disease?

Answer 6

• Diet changes: less salt/protein (reduces strain on kidneys, reduced sodium retention and lowers blood pressure)
• Dialysis for acute kidney failure
• Angiotensin-converting enzyme (ACE) inhibitors (lower blood pressure)
• Kidney transplant
• Diuretics (remove excess fluid and increase urine production)
• Corticosteroids (decrease inflammation)

Question 7

2a) Describe and explain the significance of the indicated features from the haematology results, biochemistry results and any other aspects you consider significant to the diagnosis/patient symptoms. You may use features from the patient and normal blood films for comparison.

Answer 7

• Burr cells: Little significance, common in population
• Acanthocytosis cells: presence indicates glomerular bleeding as usually trapped and destroyed in spleen
• Normochromic: indicates sufficient iron supply
• Pale skin: indicates low RBC count (low oxygen and haemoglobin)
• High blood pressure: strains organs, increasing risk of heart disease/attacks
• Haematuria/Proteinuria: suggests advanced kidney damage
• Low RBC count: issues in production or regularion (destroys quicker than produces) or blood loss somewhere
• High total bilirubin: indicates liver/bile duct issues, or increase in RBC destruction
• High blood urea: Suggests urea nitrogen not properly filtered by kidneys. Or due to dehydration
• High total protein and albumin count in urine: dehydration or inflammation/chronic infection. Albumin leaks through damaged kidneys
• High erythrocyte sedimentation rate: suggests inflammation/infection

Question 8

2b) Explain what is meant by the tern extravascular haemolysis and the mechanisms by which RBCs are removed by macrophages.

Answer 8

• Erythrophagocytosis in spleen
• Filters blood to remove debris, old/damaged RBC and microorganisms
• RBC usually have ~120 day lifespan
• Many reticular fibres in spleen to support macrophages and dendritic cells
• Blood carries microorganisms to spleen, where they are filtered out and phagocytosed by macrophages and DCs, then exposed to B/T lymphocytes to initiate adaptive immune response
• Macrophages recognise RBCs by range of senescence markers
• Destruction is antagonistically controlled by effects of CD47 and Phosphatidylserine
  1. Activation of phagocytes via inflammatory mediators
  2. Chemotaxis of phagocytes
  3. Attachment (enhanced with IgG)
  4. Ingestion of cell

Question 9

2c) Because of these findings the patient was indicated to be in need of a Renal transplant. A kidney became available and a cytotoxic cross-match was undertaken to ensure donor/patient compatibility. Illustrate the principles of the complement dependant cytotoxicity cross match technique (8 marks) and demonstrate some of the advantages and disadvantages of this technique (2 marks)

Answer 9

• Mechanism of host defence where antibodies induce target cell lysis via activation of complement system
• CDC induced when C1q protein binds to Fc region of an antibody-opsinised (covered) cell
• Leads to formation of C1 complex and eventually the complement membrane attack complex (MAC) which firms pores in cell membranes, leading to lysis
• CDC is tightly regulated, using several monoclonal antibodies to attack target cells
• Powerful screening platform used in HLA typing
• CDC-HLA typing uses anti-HLA antibodies from monoclonal antibodies, incubates them with patient/donor’s lymphocytes
• Amount of dead cells is measured
• CDC assay: Incubate the patient’s serum with the donor’s lymphocytes, and second incubate after adding the rabbit complement
• Dead cells indicate an unsuitable donor