Complement and immunoglobulins represent the two major arms of humoral immunity and are discussed in detail in respective major subsections of this chapter. The complement section begins with a comprehensive overview of pathway activation, regulation, and effector mechanisms, followed by…
B lymphocytes are the subset of white blood cells specialized to synthesize and secrete immunoglobulin (Ig). Their name derives from the finding that the avian b ursa of Fabricius is a site of B-cell production. However, post-natal B-cell production in…
Natural killer (NK) cells are large, granular lymphocytes that comprise about 10% to 15% of the circulating peripheral blood lymphoctyes. These unique cells were first characterized by their ability to lyse targets independently of activating or initiating stimuli. NK cells…
Dendritic cells (DCs), originally discovered in 1973 by Ralph M. Steinman and Zanvil A. Cohn and named after their distinct stellate morphology, are important regulators of immune responses. Specialized in antigen acquisition, processing, and presentation, the hallmark of DCs is…
Aging Increase in life expectancy has resulted in a major demographic global shift toward an elderly population. As a consequence, the prevalence of a multitude of age-associated diseases has increased gradually during the last decades, resulting in an increased number…
Core Apoptosis Pathways Apoptosis is a biochemically well-defined programmed cell death that is essential for normal development and cellular homeostasis; dysregulation of apoptosis is involved in several diseases. The classical morphological features of apoptosis include cell shrinkage, membrane blebbing, nuclear…
The Cell Division Cycle The mammalian cell cycle is divided into four phases: mitosis (M), deoxyribonucleic acid (DNA) synthesis (S), and the gap phases G1 and G2 ( Fig. 17.1 ). Mitosis is recognized when cells visibly undergo cell division…
Introduction Hallmarks of hematopoietic stem and progenitor cell (HSPC) function include their dynamic metabolism, active bi-directional migration (bone marrow [BM] homing, egress, recruitment, and mobilization to the blood), durable multilineage BM and blood repopulation potential, self-renewal and chemotherapy resistance. Hematopoietic…
Cell adhesion is essential for the development and maintenance of multicellular organisms. Cell-to-cell and cell-to-matrix adhesion provide a mechanism for intercellular communication and to define the three-dimensional architecture of organs. The regulated nature of cell adhesion is particularly evident in…
Evolution of the Niche Concept In 1868, Ernest Neumann first suggested that blood cells are being replenished throughout postnatal life, and this proposal led to the attempts to localize the place of hematopoiesis. His hypothesis that blood cell production takes…