The histiocytic disorders comprise a broad grouping of hematologic and immunologic diseases united by aberrant function, differentiation, and/or proliferation of cells of the mononuclear phagocyte system. The term histiocyte historically referred to tissue phagocytes but now more precisely defines cells…
Over 350 molecular defects that result in primary immune deficiency are known to date. Many of these gene defects have been identified in recent years with the advent of whole-exome and whole-genome sequencing. The study of patients with primary immune…
Phagocytic leukocytes are an essential component of the innate immune system that has evolved to rapidly respond to the presence of invading bacteria, fungi, and parasites. This first line of host defense also includes natural killer (NK) lymphocytes, complement, and…
Any discussion of quantitative abnormalities of lymphocytes and immunoglobulins is necessarily linked because the B-cell compartment is responsible for immunoglobulin production and the T-cell compartment helps to provide the stimulus. Nevertheless, clinicians are often consulted when a quantitative disorder of…
Abnormalities of leukocyte number are commonly encountered in medical practice. The clinical significance of leukocytosis or leukopenia varies from none at all to being an early clue to a life-threatening process, whether that is a primary hematologic or secondary reactive…
By definition, extrinsic causes of hemolysis are abnormalities in the environment in which the red blood cells (RBCs), usually normal themselves, circulate. These abnormalities can be acute or chronic in nature. They can arise from congenital lesions but usually result…
Autoimmune hemolytic anemia (AIHA) is a rare autoimmune disease caused by autoimmune-mediated destruction of red blood cells (RBCs) by autoantibodies with various properties and target specificities. Exact laboratory diagnosis may sometimes be difficult; therefore, experienced diagnostic reference centers play an…
Characterization of the structure and function of red blood cell (RBC) membrane proteins and their genes ( Fig. 46.1 ) has led to considerable advances in our understanding of the molecular pathology of membrane-associated disorders, including the definition and characterization…
Red blood cells (RBCs) are highly specialized cells with the sole function of delivering oxygen to the tissues. During oxygen delivery, a highly destructive reactive oxygen species (ROS)—such as superoxide—is generated from a small fraction of the oxygen released from…
Hemoglobinopathies are inherited diseases caused primarily by mutations affecting the globin genes. Nearly 1000 mutations are known to alter the structure, expression, or developmental regulation of individual globin genes and the hemoglobins that they encode. Of these, only a few…