Primary immunodeficiencies Primary immunodeficiencies are inherited or congenital, and are generally rare. Phagocytic cell defects Complement system deficiencies Antibody-related deficiencies T-cell–associated immunodeficiencies Secondary immunodeficiencies Defects in immunity that are secondary to another cause are more common than primary causes. Read also:
T-cell activation Upon activation by antigen, signals from the TCR and coreceptors alter the pattern of gene transcription for proliferation and differentiation into effector T cells (TH1, TH2, or CTL). The effector activity of the T cell is accomplished through the cytokines that the T cell produces (see below table). TCR binding to antigen and…
Primary immune organs (thymus and bone marrow) are the sites of lymphocyte development and maturation. The creation of the antigen-specific receptors of the lymphocytes occurs during development in the primary organs before the lymphocyte encounters antigen. B-cell development occurs in the bone marrow; T-cell development begins in the bone marrow and finishes in the thymus….
The cells of the immune system are principally the white blood cells or leukocytes. These cells are derived from hematopoietic stem cells that originate in the bone marrow. Granulocytes: have prominent cytoplasmic granules containing reactive substances that kill microorganisms and stimulate other divisions of the immune response by activating inflammation. Monocytes: are leukocytes that circulate…