Question

Can you explain in detail the RBC lysis. What is the purpose of doing RBC lysis and its advantages and disadvantages. Thank you in advance!!!

Answer 1

The break down of red blood cells are called lysis of RBC or it is the releasing of their cytoplasmic contents into the blood plasma. It is also called erythrolysis or erythrocytolysis. The lysis may occur inside the body (in vivo) or outside the body (in vitro).

It occurs normally in a small percentage of rbc as means of removing aged cells from bloodstream and freeing heme for iron recycling.

RBC lysis may occur due to the action toxins produced by certain pathogenic bacteria or fungi and intense physical exercise.

Physiology

In vitro hemolysis occurs in result from lysis of rbc during collection and handling of blood sample ( during specimen collection and from mechanical blood processing during surgery).

In vivo hemolysis occurs if the rate of erythrocyte dèstruction is increased, thereby decreasing erythrocyte lifespan.

Erythrolysis can occur in blood vessels and heart (intravascular) which may lead to hemoglobinemia, hemoglobinuria and decreased serum haptoglobin concentration.

Erythrolysis may also occur in macrophages (extravascular and intracellular hemolysis) of the mononuclear phagocytic system of spleen, liver and bone marrow. Extravascular hemolysis causes hemolytic icterus (hyperbilirubinemia).

Causes of In vivo hemolysis are:

1. Infections due to gram positive bacteria (e.g., streptococcus, enterococcus, staphylococcus)

2. Paracytic infections ( e.g., plasmodium)

3. Autoimmune disorders( hemolytic anemia)

4. Genetic disorders ( sickle cell disease, G6PD deficiency)

5. Hypotonic blood cells ( blood with too low solute concentrations)

6. Intrinsic causes; defects in rbc cell membrane, hemoglobin production and their metabolism

7. Extrinsic causes: may cause due to problem in the rbc's environment like, infection in mycoplasma, autoimmune disorders, hypersplenism, lead poisoning.

8. Intravascular hemolysis may occur due to autoantibodies leading to complement fixation or by damage due to parasites like Babesia.

Hemolysis can lead to release of haemoglobin into blood plasma which may lead to increased risk of sepsis due to its effects on innate immune system.

Purpose of doing rbc lysis:

1. To visualize and determine the species of various gram positive bacterial infections in blood.

2. To detect and diagnose many hemolytic disorders.

3. Hemolysis is used as specific labpratory test for antigen antibody reaction.

Advantages of hemolysis:

1. It removes aged rbc from blood stteam and frees heme for iron recycling.

2. Hemolysis leads to hemoglobinemia and hemoglobinuria and decrease serum haptoglobin.

Disadvantages:

1. Free hemoglobin released during hemolysis inactivated the vasodilator nitric oxide. Hemolysis also release arginase which depletes L-arginine, the substance needed for nitric oxide synthesis. These factors induces thrombin generation and activation of platelet, procoagulant and tussue factor contributing formation of thrombosis. This can lead to conditions like esophageal spasm, dyspagia, abdominal pain, erectile dysfunction, Systemic hypertension, decreased organ perfusion and promotion of inflammation ad coagulation.

2. Chronic hemolysis may lead to endothelial dysfunction and vasculopathy. The production of bilirubin and depletion of plasma proteins may cause jaundice. It also may cause increase heme breakdown and cause stercobilin.

It also effects kidneys and bone marrow workload to secrete erythrocytes.