Lymphocyte Quiz

Lymphocytes: Key Mediators of Adaptive Immunity

• Lymphocytes are cells that produce specific receptors for diverse antigens and are essential for adaptive immunity.
• A healthy adult has 0.5 to 1 × 1012 lymphocytes, which are morphologically similar but heterogeneous in lineage, function, and phenotype.
• B lymphocytes produce antibodies and mediate humoral immunity by expressing membrane-bound antibodies that recognize antigens and initiate activation of the cells.
• T lymphocytes are responsible for cell-mediated immunity and recognize only peptide fragments of protein antigens bound to MHC molecules.
• CD4+ T cells help B lymphocytes produce antibodies and phagocytes destroy microbes, while CD8+ T cells kill cells harboring intracellular microbes.
• Regulatory T lymphocytes prevent or limit immune responses.
• Naive lymphocytes recognize microbial antigens and differentiate into effector cells and memory cells, which are initiated by antigen recognition.
• Effector lymphocytes are differentiated progeny of naive cells that have the ability to produce molecules that eliminate antigens.
• Effector B lymphocytes are antibody-secreting cells called plasma cells that produce antibodies in response to antigenic stimulation.
• Effector CD4+ T cells produce cytokines that activate B cells, macrophages, and other cell types.
• Effector CD8+ T cells have the machinery to kill infected host cells.
• Memory cells are generated from antigen-stimulated lymphocytes and can survive for long periods in the absence of antigen, rapidly responding to initiate secondary immune responses when encountering the same antigen.

Lymphocytes: Key Mediators of Adaptive Immunity

• Lymphocytes are cells that produce specific receptors for diverse antigens and are essential for adaptive immunity.
• A healthy adult has 0.5 to 1 × 1012 lymphocytes, which are morphologically similar but heterogeneous in lineage, function, and phenotype.
• B lymphocytes produce antibodies and mediate humoral immunity by expressing membrane-bound antibodies that recognize antigens and initiate activation of the cells.
• T lymphocytes are responsible for cell-mediated immunity and recognize only peptide fragments of protein antigens bound to MHC molecules.
• CD4+ T cells help B lymphocytes produce antibodies and phagocytes destroy microbes, while CD8+ T cells kill cells harboring intracellular microbes.
• Regulatory T lymphocytes prevent or limit immune responses.
• Naive lymphocytes recognize microbial antigens and differentiate into effector cells and memory cells, which are initiated by antigen recognition.
• Effector lymphocytes are differentiated progeny of naive cells that have the ability to produce molecules that eliminate antigens.
• Effector B lymphocytes are antibody-secreting cells called plasma cells that produce antibodies in response to antigenic stimulation.
• Effector CD4+ T cells produce cytokines that activate B cells, macrophages, and other cell types.
• Effector CD8+ T cells have the machinery to kill infected host cells.
• Memory cells are generated from antigen-stimulated lymphocytes and can survive for long periods in the absence of antigen, rapidly responding to initiate secondary immune responses when encountering the same antigen.