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SUMMARY
This chapter outlines the major categories of lymphocyte and plasma cell disorders.* The disorders are classified into three main groups. The first is composed of diseases caused by defects intrinsic to lymphoid cells. The second is caused by disorders that result from factors extrinsic to lymphoid cells. The third is composed of disorders caused by neoplastic or preneoplastic lymphoid cells and are outlined in Chap. 90 using the World Health Organization classification of tumors of lymphoid tissues. The clinical manifestations of diseases in any one of the three groups may be difficult to distinguish, but this grouping can provide a framework with which to proceed in evaluating patients with known or suspected lymphocyte and plasma cell disorders. This chapter introduces the framework and presents a roadmap to other chapters in this book that discuss each of the disorders in greater detail.
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Acronyms and Abbreviations
GVHD, graft-versus-host disease; Ig, immunoglobulin; NK, natural killer; SCID, severe combined immune deficiency; Th, T helper; TREG, CD4+ regulatory T cell.
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Lymphocyte and plasma cell disorders can be classified into three major groups (Table 78–1). The first group, listed under “primary disorders,” is composed of lymphocyte disorders caused by intrinsic defects in lymphoid cells that result in functional abnormalities of marrow-derived (B) lymphocytes, thymic-derived (T) lymphocytes, combined T and B (impaired humoral and cellular immunity), or natural killer (NK) cells. These disorders primarily result from inborn errors in lymphocyte metabolism (Chaps. 73 to 77 and 80) and/or receptor–ligand expression (Chaps. 17 and 80). The second group, listed under “acquired disorders,” consists of disorders caused by factors extrinsic to lymphocytes resulting in immune dysfunction. These conditions most commonly result from infection with viruses, or other cellular pathogens (Chaps. 79, 81, and 82), but they also may be caused by bacteria, drugs or systemic disease of nonlymphoid cells. The third group of diseases is composed of preneoplastic and neoplastic lymphocyte disorders and is discussed in detail in Chap. 90.
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