Blood cells and
Types
Humoral immunity and cell-mediated immunity is a part of active immunity.
They are the mechanisms which protect our body against diseases when our innate immune
system fails.
The Functions Include:
Recognition of specific non-self-antigens and presence of self-antigens.
Generate responses to eliminate specific pathogens or pathogen-infected cells.
Development of immunological cells.
Humoral immune activity is one of the mechanisms of the active immune system and is associated with circulating
antibodies in contrast to cellular immunity. The wide range antibody activities is a response to rapid production of
antigen-specific B cells during infections which increases antibody titres with enhanced affinity for the inciting agent
and more directed and effective response.
Cell-mediated immunity is a type of adaptive immune response that does not involve antibodies but it does involve
the activation of NK cell and macrophages and the production of antigen-specific cytotoxic T-lymphocytes and the
release of several cytokines in response to a foreign antigen. Cell-mediated immunity plays an important role in
controlling viral, chlamydia, rickettsia and protozoan infections such as trypanosomes as antibodies cannot
penetrate and attack intracellular pathogens which multiply within the host cells.
B lymphocyte is a type of white blood cell that
develops in the bone marrow and makes
antibodies.
This cell type is classified into four main groups:
Transitional, Naïve, Plasma, and Memory B cells.
Transitional B cells are B cells at an
intermediate stage in their development
between bone marrow immature cells and
mature B cells in the spleen.
A naive B cell is a B cell that has not been
exposed to an antigen. Once exposed to an
antigen, the naive B cell either becomes a
memory B cell or a plasma cell that secretes
antibodies specific to the antigen that was
originally bound.
Memory B cell are the B cells that are long
lived and remember past antigen exposure.
Plasma B cell are Activated B cells that
produce antibodies. Only one type of antibody
is produced per plasma B cell.
T lymphocytes mature in the thymus and differentiate into
cytotoxic, memory, helper and regulatory T cells.
Cytotoxic T cells are the primary effector cells of adaptive
immunity. Activated cytotoxic T cells can migrate through blood
vessel walls and non-lymphoid tissues. They can also travel
across the blood brain barrier. Cytotoxic T cells are activated by
cytokines. They can attach to cancer cells and kill them.
Memory T cells are derived from activated cytotoxic T cells,
memory T cells are long-lived and antigen-experienced. One
memory T cell can produce multiple cytotoxic T cells. After
activated cytotoxic T cells attack the pathogen, the memory T cells
hang around to mitigate any recurrence.
Helper T cells secrete cytokines that help B cells differentiate into
plasma cells. These cells also help to activate cytotoxic T cells and
macrophages.
Regulatory T cells are a specialized subpopulation of T cells that
act to suppress immune response, thereby maintaining
homeostasis and self-tolerance. It has been shown that Tregs are
able to inhibit T cell proliferation and cytokine production and play
a critical role in preventing autoimmunity.
Natural killer (NK) cells are the predominant innate lymphocyte subsets that mediate anti-tumor and anti-viral
responses, and therefore possess promising clinical utilization
Natural Killer (NK) Cells are lymphocytes in the same family as T and B cells, coming from a common progenitor.
... Additionally, NK cells secrete cytokines such as IFNγ (Interferon) and TNFα (Tumor necrosis factor), which act
on other immune cells like Macrophage and Dendritic cells to enhance the immune response.
