Immunology & Inflammation

Basic defense mechanisms

specific and generic immune responses to harmful stimuli

Immunology and Inflammation are two basic defense mechanisms of mammalian organisms to respond to harmful stimuli.

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Immunology

the innate and adaptive immunity

Immunology defines an area of biology that deals with the immune system of organisms and finds application in a variety of disciplines. It plays an important role in medicine, especially in oncology, virology, rheumatology and many more. The main focus of immunology is the research of the physiological function of the immune system and the analysis of the immunological state in health and disease.

Immunological research includes the complex cellular and humoral immunity as well as their cooperation of the physiological and biochemical processes in the whole organism associated with an immune response. The immune reactions can be triggered by contact with infectious pathogens or other antigens. Immune cells, derived in the mone marrow from hematopoetic stem cells are the key player in controlling the immune response to pathogenic antigens. Pluripotent hematopoietic stem cells can generate lymphocytes, which are responsible for adaptive immunity, and myeloid lineages, which are involved in both innate and adaptive immunity. The myeloid lineage gives rise to neutrophils, basophils and eosinophils, also called granulocytes, macrophages and dendritic immature cells act as effector cells for infection and inflammation. The main function of macrophages is the phagocytosis of bacteria and the recruitment of other phagocytic cells whereas mast cells are involved in the defense against parasites and the recruitment of eosinophils and basophils. Another important group of myeloid lineage derived cells are the dendritic cells. After they enter the tissue as immature phagocytes, they become specific for antigen uptake and migrate into the lymphatic tissue as antigen-presenting cells. Upon antigen presentation, T-lymphocytes and B-lymphocytes immediately start proliferating and differentiate into antigen-specific effector cells (T-cells) and antibody secreting cells (B-cells), repsectively.

Inflammation

genric response to harmful stimuli

Inflammation is a generic response involving immune cells, blood, vessels and mediators induced by several stimuli like pathogens, damaged cells or other irritants. The major function is the elimination of the initial cause of the inflammatory immune response which can be cell injury, necrotic cells and other tissue damages to further initiate tissue repair. Since the inflammatory response is not specific to the e.g. a pathogen, it belongs to the mechanisms of the innate immune system. While a lack of inflammation or a weak inflammatory response can lead to tissue destruction and thus negatively affect survival of the organism, an extensive imflammatory response for example a chronic inflammation is strongly associated with several diseases like atherosclerosis.

The initial response is classified as acute inflammation and includes infiltration of plasma and leucocytes into the injured tissue. The maturation of the inflammatory response following the acute inflammation involves the vascular system, the immune system and translocation of various cells into site of injury.

If the inflammatory response continues over a prolonged time frame, the cell types present at the site of inflammation progressively shift to more mononuclear cells. This process is then described as chronic inflammation.