humoral immunity

(redirected from Antigens, t-independent)
Also found in: Dictionary, Encyclopedia.

hu·mor·al im·mu·ni·ty

immunity associated with circulating antibodies, in contradistinction to cellular immunity. The inherent range of activity of antibody specificities is wide but proliferation of antigen-specific B cells occurs rapidly during infections leading to rapid increases in antibody titers with enhanced affinity for the inciting agent, and a more effective and directed response.

humoral immunity

n.
Immunity involving the transformation of B-lymphocytes into plasma cells that produce and secrete antibodies to a specific antigen.

hu·mor·al im·mu·ni·ty

(hyū'mŏr-ăl i-myū'ni-tē)
Immunity associated with circulating antibodies, in contradistinction to cellular immunity.
Enlarge picture
HUMORAL IMMUNITY

humoral immunity

The protective activities of antibodies against infection or reinfection by common organisms, e.g., streptococci and staphylococci. B lymphocytes with receptors to a specific antigen react when they encounter that antigen by producing plasma cells (which produce antigen-specific antibodies) and memory cells (which enable the body to produce these antibodies quickly in the event that the same antigen appears later). B-cell differentiation also is stimulated by interleukin-2 (IL-2) secreted by CD4+ T cells and foreign antigens processed by macrophages.

Antibodies produced by plasma B cells, found mainly in the blood, spleen, and lymph nodes, neutralize or destroy antigens in several ways. They kill organisms by activating the complement system; neutralize viruses and toxins released by bacteria; coat the antigen (opsonization) or form an antigen-antibody complex to stimulate phagocytosis; promote antigen clumping (agglutination); and prevent the antigen from adhering to host cells.

Synonym: B-cell–mediated immunity See: illustration; cell-mediated immunity; immunoglobulin
See also: immunity