Pharmaceuticals & RBCs Flashcards
1
Q
Describe RBCs
A
- 5.5 x 10^12 /L
- synthesised in bone marrow
- lifespan = 120 days
- immature red cells = reticulocytes
2
Q
What do reticulocytes contian ?
A
remnants of mRNA, visible under microscope
3
Q
Describe the Penicillin Case study
A
- woman 64yo
- 1988 = bacterial endocarditis treated with intramuscular penicillin 13 weeks
- no reaction
- several years later admitted & treated with penicillin - 15 days later rash
- 2nd exposure caused haemolytic response
4
Q
Describe the AntiGlobulin Test (DAT)
A
- RCs taken from patient
- adding anti-IgG to detect IgG that is attached to RBCs
- detects C3 complement fragments on RBC surface
5
Q
When is a DAT performed ?
A
- to investigae immune haemolytic anaemia & transfusion reactions
6
Q
Why did the 64yo woman react to penicillin the 2nd time?
A
- 1st time penicillin was used at high dose & absorbed onto surface of RCs
- immune system recognised this as foreign & synthesises antibodies (IgG) & memory cells
- 2nd use = antibody increases in plasma & binds to penicillin coated RCs
7
Q
What happens to penicillin coated RCs?
A
- engulfed by macrophages
OR - binds complement which leads to lysis of RCs
8
Q
How does the bone marrow respond to RC destruction?
A
- increases rate of red cell production
- releases reticulocytes into circulation
9
Q
How can this reaction to penicillin be treated?
A
- stop penicillin treatment
- administer steroids to supress immune system
- plasmaphoresis & transfusion in special cases
10
Q
Describe Dapsone
A
- antibacterial agent used to treat Mycobacterium tuberculosis
- causes oxidation of haemoglobin to a form called methaemoglobin (non-functional)
- induces denaturation of methaemoglobin to form Heinz bodies
11
Q
What happens to Heinz Bodies?
A
- recognised by macrophages
- bitten out
- creates a ‘bite cell’ in circulation
