Nonspecific immunity

From WikiLectures

Nonspecific immune mechanisms (also innate', natural', non-adaptive) are innate. This means that all necessary information is invariably written in DNA and already present in the zygote. Nonspecific immunity responds after each encounter with an antigen by the same mechanisms, has no memory'.

It consists mainly of complement components and phagocytes. It is not aimed at the destruction of a specific antigen, but it is very fast. The cells are constantly present in the blood, so that activation is almost instantaneous (minutes to hours) when needed.

It is evolutionarily older (in all multicellular organisms to varying degrees) than specific immunity. It consists of cellular and humoral components.

This group also includes barrier functions of the body', i.e. skin, mucous membranes, etc. (generally structures that prevent foreign particles from entering the body).

Aggregation of the components of natural immunity[edit | edit source]

Cellular components[edit | edit source]

Humoral components[edit | edit source]

Cellular component[edit | edit source]

These include mainly granulocytes, macrophages and some lymphocytes. Thrombocytes may also be included, but play a minor, but not unimportant, role.

Granulocytes and macrophages[edit | edit source]

The bulk of the cellular component of non-specific immunity is composed of cells arising from the myeloid lineage. This includes cells that exhibit high phagocytic capacity, i.e. macrophages and neutrophil granulocytes. Antigen-presenting cells, which include mainly dendritic cells (cooperating with T-ly) and follicular cells (presenting Ag to B-ly), cannot be overlooked. This group also includes eosinophils' and basophils'.

Lymphocytes[edit | edit source]

The next part is the cells of the lymphoid line. These include mainly cytotoxic NK cells (natural killers). Some immunologists also include some B-lymphocytes in this group due to their independence from T-lymphocytes and the possibility of partial change of their specificity during proliferation. These are B-cells that recognize carbohydrate antigens.

Humoral component[edit | edit source]

Acute phase proteins[edit | edit source]

This is a group of proteins whose levels rise significantly and relatively quickly after the immune system is activated. Complement components are also included here, but are separated for clarity.

Searchtool right.svg For more information see Acute Phase Proteins.

Complement[edit | edit source]

Complement is a set of serum proteins capable of inducing lysis of certain cells when activated.

Searchtool right.svg For more information see Complement.

Cytokines[edit | edit source]

Cytokines are a very diverse group of signal peptides, some of which have a hormonal function. Their production varies significantly with the degree of cell activation. They mediate communication between cells of specific and non-specific immunity. We divide them into several subgroups:

  • interleukins,
  • chemokines,
  • interferons.
Searchtool right.svg For more information see Cytokines, Interleukins, Chemokines, Interferons.

Principles of non-specific mechanisms[edit | edit source]

Identification of pathogenic patterns[edit | edit source]

Pathogens are identified by the presence of PAMP (Pathogen-Associated Molecular Pattern) - phylogenetically highly conserved structures. They are carried only by microorganisms and are essential for their survival. They include:

These patterns are recognized by the PPR (Pathogen Pattern Receptor) = PRR' (Pattern Recognition Receptor). They are of the following types:

  • secernated' - opsonins (e.g. MBL) of complement activation,
  • endocytic' - on phagocytes, mediate phagocytosis (e.g. MMR (mannose macrophage receptor), MSR (macrophage scavenger receptor) - cleans up bacterial debris),
  • signalling' - activate a signalling pathway leading to the production of cytokines (e.g. TLR (Toll-like receptor)).

Identification of endogenous patterns[edit | edit source]

In the context of apoptosis, ACAMP (Apoptotic Cell Associated Molecular Pattern) patterns are exhibited - e.g., phospholipids of the inner layer of the cell membrane. They are recognized by the ACR (Apoptotic Cell Receptor), rather anti-inflammatory cytokines are produced.

Antigen presentation[edit | edit source]

Antigen Presenting Cells (APCs) engulf antigens, process them in lysosomess and present them on HLA class II molecules. Thus processed, antigens (or antigenic epitopes) are presented together with costimulatory signals to T-lymphocytes.

Note: If any cell, not just the antigen presenting cell, is infected with an intracellular parasite, the antigen is presented on HLA Class I.

Links[edit | edit source]

Related articles[edit | edit source]

References[edit | edit source]

  • HOŘEJŠÍ, Václav – BARTŮŇKOVÁ, Jiřina. Základy imunologie. 3. edition. Praha : Triton, 2008. 280 pp. ISBN 80-7254-686-4.

  • KREJSEK, Jan – KOPECKÝ, Otakar. Klinická imunologie. 1. edition. Hradec Králové : Nucleus HK, 2004. 941 pp. ISBN 80-86225-50-X.

  • ŠTERZL, Ivan. Základy imunologie. 1. edition. Praha : Karolinum, 2005. ISBN 80-246-0972-X.