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Immune System:

1. Central

2. Peripheral

3. Immune Cells

Consists of:

1. Central Structures
2. Peripheral Lymphoid Organs/Tissues
3. Immune Cells.

Central organs include:

1. bone marrow where new stem cells are produced, and
2. the thymus gland, where T-lymphocytes reach full maturation.

Peripheral lymph organs:

1. lymph nodes, spleen, and tonsils, while lymphoid tissue is found in non-lymphoid organs such as
2. the intestine and others......

Immune cells include:

1. lymphocytes: these are B cells and T cells (70-90%) and Natural Killer cells.
2. macrophages.

Lymphocytes

Macrophages

B-cells

Memory cells
Antibody-secreting (Ig) plasma cells

T-cells

Regulator T cells
Effector T cells

Natural Killer Cells

Non-B lymphocytes
Non-T lymphocytes

Macrophages/Monocytes

Monocytes
Tissue macrophages

Lifespan - 24-72 hrs
Two possibilities:
1. Destroyed in spleen or lymphoid tissue
2. Antigen encounter and maturation

Lifespan - years
Found in:
1. bloodstream

2. lymphnodes, spleen, other lymph tissues

Probably similar to T cells; not as much known about this lymphocyte

Monocytes disperse through-out body

become tissue macrophages in organs/tissues - liver, lymph nodes, lungs, etc.

Produce antibodies (Igs or immunoglobulin proteins) which destroy antigens

Cell-mediated immunity; non-Ig surface cell receptor (TCR) develops in thymus

Cell-mediated immunity; active in tumor and viral destruction although their primary role is unknown

Antigen-capturing cells; essential to both B and T cell function

Antigen binds to surface immunoglobulins (sIgs)

secretion & proliferation of antibodies specific to antigen

Lead immune response on encounter with macrophage antigen

release lymphokines (cytokines)

activate macrophages; recruit other T cells & B cells.

Function without prior sensitization

Destroy many tumor and viral cells through close contact

Ingest and process micro-organism/antigen

present antigen on cell surface with 11 MHC gene products to lymphocyte

this process accelerates in presence of other antibodies.

Release cytokines (non-Ig proteins) in response to antigen recognition or other stimulus

Can recognize antigen only in association with MHC-membrane-bound products

Action increased by interferons and interleukin-2

Produce interleukin-1 (inflammatory mediator)