CONTENTS:
- When the Immune System Targets More Than One Part of the Blood
- Immunosuppressants: Read about this treatment approach, mechanism of action, benefits, and side effects
In this month’s e-News, PDSA Medical Advisor Michele Lambert, MD, MSTR, shares what ITP patients need to know if they have two or more immune related cytopenias (low blood cell counts) and highlights the importance of proper diagnosis and treatment. Dr. Lambert is an Assistant Professor of Clinical Pediatrics at the Children’s Hospital of Philadelphia and Medical Director of the Special Coagulation Laboratory at CHOP. Her research efforts have focused on understanding the control of platelet production by megakaryocytes (the cells that make platelets) and the ways in which genetics influence platelet function and number in various clinical scenarios including ITP and inherited platelet disorders.
When the Immune System Targets More Than One Part of the Blood
- By Michele Lambert, MD, MSTR
Most patients with ITP (80%) have primary ITP, meaning that the immune system reacts to the patient’s platelets, but there is no identified underlying cause for this reaction. These patients do not have underlying rheumatologic diseases such as Lupus, or immune disorders such as Common Variable Immunodeficiency (CVID) or Autoimmune Lymphoproliferative Syndrome (ALPS) infection (such as hepatitis or HIV) or malignancy (such as Chronic Myelogenous Leukemia).
In some patients, especially in about half of children with ITP, there is a preceding viral illness that may trigger the initial immune response, but that illness can be very non-specific and rarely even requires a visit to the doctor. In most pediatric patients, the platelet counts in ITP get better after the diagnosis and, by three to six months from when they found the first very low platelet count, the majority of patients have platelet counts that are back to nearly normal (>100k/mcL).
Some patients, however, develop ITP and their immune system also attacks another blood cell type: either the red blood cells, called Autoimmune Hemolytic Anemia (AIHA) or the neutrophils which help to fight bacterial infections, called Autoimmune Neutropenia (AIN). This second immune cytopenia (immune related low blood cell count) can happen at the same time as the ITP, or sometimes months or even years before or after the ITP. When you have two or more immune cytopenias, we call it Evans syndrome, and it occurs in between 0.8-3.7% of patients with ITP (adults and children). Patients with Evans syndrome are much more likely to have chronic disease or disease that goes away for a time and then relapses (relapsing/ remitting), and therefore, often require daily therapy to help regulate the immune system and keep blood counts stable.
Evans syndrome is named for Dr. Robert Evans who initially described the association of AIHA and ITP. Today, we know that in >65% of pediatric patients with Evans syndrome, physicians can identify an underlying immune disorder as the cause for the Evans which can help to guide treatment. Unfortunately, insurance companies can still be behind the times on approving and paying for genetic testing for these patients and it can be frustrating to evaluate these disorders. It is important to have your physician test for underlying ALPS or ALPS-like disorders (such as that caused by CTLA4 or LRBA deficiency, STAT3 gain of function, or PI3Kinase deficiency), CVID, and other immunodeficiencies that can be subtle and present at first with autoimmunity instead of infection. Some patients will be identified as having an underlying rheumatologic diagnosis such as lupus, dermatomyositis or Sjogren’s syndrome. Treatments will vary depending on the underlying cause and so establishing the correct diagnosis may alter the therapy.
Sometimes, we cannot identify the underlying cause of the Evans syndrome. In these patients, it is still important to partner between hematology and immunology and rheumatology and have regular follow up visits for monitoring, as the cause of the Evans syndrome may become more apparent over time. Some studies have suggested that it may take as many as 7-9 years before a secondary diagnosis is established in patients with underlying diagnoses.
Immunosuppressants
A class of drugs that suppress, or reduce, the strength of the body’s immune system, immunosuppressants are also referred to as anti-rejection drugs because they are used to make the body less likely to reject a transplanted organ, such as a liver, heart or kidney.
Read about this treatment approach, mechanism of action, benefits, and side effects.