Miscellaneous - Uworld etc.

Question 1

What is X-linked (Bruton) agammaglobulinemia?

Answer 1

• Defect in B cell maturation
• Results in absent mature B cells and severely low immunoglobulin levels
• T cell numbers and function remain intact
• Primary lymphoid follicles and germinal centres do not form within lymph nodes

Question 2

What cells secrete hepcidin?

Answer 2

Hepatic parenchymal cells

Question 3

What are AIP attacks primarily due to?

Answer 3

Accumulation of Aminolevulinate (ALA) and porphorobilinogen (PBG)
- Trigger usually induces ALA synthase -> increase in ALA and PBG

Question 4

What are AIP attacks treated with?

Answer 4

ALA synthase inhibitors (less build up of ALA and PBG)

• Glucose
• Hemin

Question 5

What is cold-agglutinin disease due to?

Answer 5

• Cross-reactive IgM

- Type of autoimmune hemolytic anemia

Question 6

How does G6PD deficiency result in hemolysis?

Answer 6

• NADPH + H+ isnt produced from NADP+

- Glutationine is not reduced -> remains oxidised which causes oxidative stress in the RBC

Question 7

What is replaced and where in sickle cell?

Answer 7

• Valine replaces glutamic acid at position 6 on the hemoglobin beta-globin chain
• Chromosome 11

Question 8

Tumour lysis syndrome has what electrolytes increased/decreased?

Answer 8

• Hyperphosphatemia
• Hypocalcemia
• Hyperkalemia
• Hyperuricemia

Question 9

What is Uric acid converted into by urate oxidase?

Answer 9

Allantoin (secreted in urine)

Question 10

What drug causes Uric acid to be converted to Allantoin?

Answer 10

Rasburicase

• Induces Urate oxidase
• Used in tumour lysis syndrome to prevent build up of uric acid

Question 11

What are the layers of the secondary follicle from inside to out?

Answer 11

• Germinal centre
• Mantle
• Margin

Question 12

Name the layers of the lymph node from inside to out?

Answer 12

• Cortex (contains follicles)
• Paracortex
• Medulla
• Medullary sinus

Question 13

What cells are produced by what areas of the lymph node?

Answer 13

• Cortex (in follicles) - B cells
• Paracortex - T cells
• Medulla - Plasma cells
• Medullary sinus - Macrophages

Question 14

Where are B-lymphocytes produced in the spleen?

Answer 14

Peripheral areas of the white pulp

Question 15

Where are T-lymphocytes produced in the spleen?

Answer 15

Peri-arteriolar lymphatic sheath (PALS)

Question 16

G6PD affects what pathway?

Answer 16

The pentose phosphate pathway

Question 17

How do carcinomas and sarcomas differ in the way they spread?

Answer 17

• Carcinomas = lymph

- Sarcomas = blood (metastasise to lungs, liver)

Question 18

What do secondary (mature) lymphoid follicles contain that primary do not?

Answer 18

Germinal centres

Question 19

What cells produce EPO?

Answer 19

Peritubular fibroblast cells in the renal cortex

Question 20

What are the symptoms associated with PNH?

Answer 20

• Hemolytic anemia
• Hypercoagulability
• Pancytopenia

Question 21

What gene is defective in PNH?

Answer 21

PIGA

Question 22

What protein is defective in PNH? (what dos PIGA code for)

Also what is its function?

Answer 22

Glycosylphosphatidylinositol (GPI) anchor

• Glycolipid necessary for the attachement of several cell-surface proteins, including CD55 and CD59
• Help inactivate complement and prevent the membrane attack complex from forming on normal cells

Question 23

What does JAK2 do?

Answer 23

Induces the transcription of proteins that inhibit erythrocyte precursor apoptosis and promote survival

• Also activates signals that increase differentiation of erythrocyte precursors into mature erythrocytes
• Together increases the production of erythrocytes and improve RBC counts

Question 24

Hypocalcemia and peripheral neuromuscular excitability after blood transfusion is due to what?

Answer 24

Citrate anticoagulants in high-volume blood transfusion can chelate plasma calcium, leading to hypocalcemia - causing peripheral neuromuscular excitability
- Can be seen in rapid transfusion and transfusion in patients w. hepatic insufficiency