Paroxysmal nocturnal hemoglobinuria is associated with which flow cytometry findings?

Paroxysmal nocturnal hemoglobinuria is associated with which flow cytometry findings?

• A. Increased CD55 and CD59
• B. Decreased CD55 and CD59
• C. Normal CD55 and CD59
• D. Increased CD34 expression

Answer: (B)

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare acquired hematologic disorder that affects red blood cells and is characterized by the destruction of these cells due to complement-mediated lysis. This occurs because PNH results from a mutation in the hematopoietic stem cells, leading to a deficiency of glycosylphosphatidylinositol (GPI)-anchored proteins, which are crucial for the protection of red blood cells from the complement system. CD55 and CD59 are two important GPI-anchored proteins that normally serve to inhibit the complement cascade on the surface of red blood cells. In patients with PNH, the absence or reduced expression of these proteins is a direct consequence of the underlying genetic mutation. Therefore, when flow cytometry is performed on the blood from a patient with PNH, a decrease in the expression of CD55 and CD59 is seen. This leads to a higher susceptibility of the red blood cells to complement-mediated hemolysis, which is why patients experience symptoms such as hemoglobinuria, especially during nighttime when complement activation can be heightened due to acidosis during sleep. In contrast, the other choices presented do not align with the pathophysiological basis of PNH. Normal

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare acquired hematologic disorder that affects red blood cells and is characterized by the destruction of these cells due to complement-mediated lysis. This occurs because PNH results from a mutation in the hematopoietic stem cells, leading to a deficiency of glycosylphosphatidylinositol (GPI)-anchored proteins, which are crucial for the protection of red blood cells from the complement system.

CD55 and CD59 are two important GPI-anchored proteins that normally serve to inhibit the complement cascade on the surface of red blood cells. In patients with PNH, the absence or reduced expression of these proteins is a direct consequence of the underlying genetic mutation. Therefore, when flow cytometry is performed on the blood from a patient with PNH, a decrease in the expression of CD55 and CD59 is seen. This leads to a higher susceptibility of the red blood cells to complement-mediated hemolysis, which is why patients experience symptoms such as hemoglobinuria, especially during nighttime when complement activation can be heightened due to acidosis during sleep.

In contrast, the other choices presented do not align with the pathophysiological basis of PNH. Normal