The Handbook ~ Immune Thrombocytopenia


Immune thrombocytopenia (ITP) is an autoimmune disorder that causes thrombocytopenia and puts patients at increased risk for bleeding. It has been a recognised clinical entity since the 19th century and can affect individuals of all ages. ITP may be associated with other clinical disorders of the immune system (eg, systemic lupus erythematosus) or lymphoma, but commonly is associated with no other identifiable disease.

In recent years considerable new information has been uncovered as to the aetiology of ITP (eg, it is a disorder of both increased platelet destruction as well as inappropriately low platelet production) and new therapies have been developed (eg, thrombopoietin [TPO] mimetics). This ITP Handbook reviews these new advances in pathophysiology and treatment.

In the first section, the basic science of ITP is reviewed. This includes discussion of megakaryocyte differentiation and platelet production as well as a review of autoimmune mechanisms and T regulatory cell disturbances in ITP. Mouse models of ITP that explain the concepts of increased platelet destruction and inhibition of platelet production are then explored along with the possible utility of peptide therapy directed at GPIIb/IIIa on the platelet membrane.

The second section assesses the clinical dilemmas in ITP. After reviewing the pathophysiology of ITP, studies using Indium labelled platelets are reviewed to see if they can predict the response to splenectomy. This section is concluded with a discussion of the recent international guidelines for the treatment of ITP.

The third section reviews new and novel approaches to treating ITP. The biochemistry and biology of the new TPO mimetics (eltrombopag and romiplostim) is presented along with a complete review of the clinical studies of these agents in ITP. The biology and clinical studies with another novel ITP therapy, rituximab, are then explored in detail. The final topic in this section explores the unique and evolving biology of how Fc receptor therapies work in ITP.

The fourth section explores future approaches to the treatment of ITP. Further investigations of Fc receptors and how they might be further targeted for therapy is presented along with the prospect that regulatory antibodies might also be exploited in treatment. The participation of cytotoxic T-lymphocytes in ITP is discussed and the section concluded by a discussion of how these future approaches might lead to better understanding and treatment of ITP.

The reader of this ITP Handbook should come away with a clearer understanding of the pathophysiology of ITP and its current treatment as well as an overview of where future ITP research is directed. It will be of interest to the medical professional and to the educated ITP patient or family member.

Douglas B. Cines
University of Pennsylvania
David J. Kuter
Harvard Medical School
Adrian C. Newland
Barts & The London School of Medicine and Dentistry
Drew Provan
Barts & The London School of Medicine and Dentistry
John W. Semple
St. Michael’s Hospital, Toronto