Our study involves the analysis of normal and abnormal cells in the bone marrow of patients with Paroxysmal Nocturnal Hemoglobinuria (PNH). In this condition, due to a gene mutation, some bone marrow cells and their progeny in the blood lack an important cell surface component that functions as an anchor for other proteins, some of which attach to blood cells and protect them from destruction by complement, part our immune system. The result of this deficiency is a breakdown of red cells. If large quantities of red cells are destroyed, people become very tired, or have pain in the belly, head or when swallowing, or develop blood clots. The cause of the gene mutation is unknown. Some patients with other conditions, such as aplastic anemia (AA, a disease where marrow stops producing blood cells), or myelodysplasia (MDS, a disease associated with a tendency to transform into leukemia), may develop PNH. It is not clear what makes this change occur, and when it happens, patient may not even be aware of it, because patients with AA and MDS usually have few cells of the PNH type. However, over time, the symptoms could worsen due to an increase in the number of affected cells, and patients may need treatment to prevent red cell destruction.
Tests for PNH
These tests include a complete blood count (the number of cells in blood), and tests assessing red cell breakdown. For detecting PNH, doctors use an instrument called flow cytometer, which detects and counts cells with anchor protein deficiencies on the surface of cells in blood. If PNH is present, it is important to know how many cells are affected and to what degree (they can be partially or completely abnormal), because patients symptoms vary according to these parameters. A new reagent, called FLAER, allows the detection of cells missing the critical anchor proteins in PNH patients and is widely used in the detection and counting of abnormal cells in blood.
Why study the marrow in patients with PNH?
In many patients with AA and MDS, we often detect PNH cells in the blood. In these patients, we plan to determine which marrow cells and how severe, they are affected. Using the power of flow cytometer in recognizing distinctive types of cells, we will use FLAER to study the presence and distribution of anchor proteins in the various populations of cells residing in the human marrow, in normal individuals and in patients with PNH. This information should provide unique insights into the biology of PNH and may help diagnosing PNH in patients with cytopenias in whom marrows are examined for diagnostic purposes without a clinical suspicion of PNH. Furthermore, since cells in both, normal or diseased marrows actively proliferate and many naturally die, we plan to measure the fraction of normal and PNH cells undergoing cell division and cell death in the same marrow. We expect that this information would allow us to predict changes in PNH clonal size over time that should have clinical relevance.