Difference Between Cell Mediated and Humoral Immune Systems

The humoral immune response (HIR) is the aspect of immunity that is mediated by secreted antibodies (as opposed to cell-mediated immunity, which involves T lymphocytes) produced in the cells of the B lymphocyte lineage (B cell). B Cells (with co-stimulation) transform into plasma cells which secrete antibodies. The co-stimulation of the B cell can come from another antigen presenting cell, like a dendritic cell. This entire process is aided by CD4+ T-helper 2 cells, which provide co-stimulation. Secreted antibodies bind to antigens on the surfaces of invading microbes (such as viruses or bacteria), which flags them for destruction. Humoral immunity is so named because it involves substances found in the humours, or body fluids.

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Cell-mediated immunity is an immune response that does not involve antibodies but rather involves the activation of macrophages, natural killer cells (NK), antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen. Historically, the immune system was separated into two branches: humoral immunity, for which the protective function of immunization could be found in the humor (cell-free bodily fluid or serum) and cellular immunity, for which the protective function of immunization was associated with cells. CD4 cells or helper T cells provide protection against different pathogens. Cytotoxic T cells cause death by apoptosis without using cytokines, therefore in cell mediated immunity cytokines are not always present.
Cellular immunity protects the body by:
  1. activating antigen-specific cytotoxic T-lymphocytes that are able to induce apoptosis in body cells displaying epitopes of foreign antigen on their surface, such as virus-infected cells, cells with intracellular bacteria, and cancer cells displaying tumor antigens;
  2. activating macrophages and natural killer cells, enabling them to destroy pathogens; and
  3. stimulating cells to secrete a variety of cytokines that influence the function of other cells involved in adaptive immune responses and innate immune responses.

Source: http://arapaho.nsuok.edu/~castillo/NotesImages/Topic5NotesImage4.jpg

Source: http://uhaweb.hartford.edu/bugl/immune.htm

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