ACUTE (short-term) inflammation - Needed and immediate

Necessary for survival, and is the immune system's IMMEDIATE response to infection or injury

Acute phase Inflammation Response

ACUTE PHASE inflammation is the body's immediate, necessary and appropriate response to infection or injury - occuring within minutes to hours

Mechanism of Acute Inflammatory Phase

-   Without inflammation, infections would go unchecked and wounds would never heal.   E.g.  from trauma, surgery, burns;

-   Symptoms.    The damage site becomes red, swollen and warm, with possible loss of function, as healing mechanisms are initiated.

-   Repair the damage.    Fibroblasts manufacture the extracellular matrix (ECM) and collagen to repair damaged connective tissue

-   Acute inflammation response is designed to work best in a well-nourished person with a mild to moderate injury /infection over a short period of time.

Part of the innate immune system (I.S.)

Innate Immunity - "General Soldiers" - 1st line of nonspecific immune system's defense against invading organisms.   Immediately or within several hours after an "invasion". Innate immunity includes mechanical barriers, such as the skin, chemicals in the blood and immune system cells that attack invading, foreign cells.

Chemicals released to cause inflammation attract white blood cells called phagocytes (E.g. macrophages and neutrophils) - which engulf foreign particles (E.g. chemicals, particulate matter), bacteria, parasites, dead/dying body cells and debris; being messy “eaters”, macrophages “burp up”fragments of their “meal”that alert other I.S. cells to join the fight and they also produce chemicals to kill microbes;

•   Different methods are employed to kill microbes.   Intracellularly, phagocyte oxygen consumption increases in a so-called “respiratory burst”, which produces anti-microbial ROS, namely: Singlet oxygen, Hydroxyl radical and Hypochlorite; extracellularly, nitric oxide is used against bacteria; some of these oxidants leak into and damage surrounding tissue, causing more inflammation, especially if the “battle “goes on for too long;

•   Tumor Necrosis Factor-α (secreted by activated macrophages) is used to destroy virally infected cells/cancer cells:

•   Pus - is a combination of dead tissue, dead bacteria, and live and dead phagocytes.

Macrophages “Dealing with”a parasite

Macrophage “eating” carbon particles in particulate matter

(The black material is inhaled carbon in sputum induced from a healthy child's lung)

The damaged/infected site becomes red, swollen and warm, with possible loss of function - as healing mechanisms are initiated.

Eventually any damage is repaired - fibroblasts manufacture the extracellular matrix (ECM) and collagen to repair damaged connective tissue (admittedly sometimes leaving a scar);

Acute inflammation response is designed to work best in a well-nourished person with a mild to moderate injury /infection over a short period of time -response usually occurs within minutes to hours, and the problem is often fixed in a few days;

Part of the adaptive immune system (I.S.)

Adaptive immunity - "Specialized Troops” - 2nd line of defense and protection against re-infection by same pathogen

HUMORAL immunity - involves production of antibodies in response to an antigen and is mediated by B-lymphocytes

CELL-MEDIATED immunity - involves production of cytotoxic T-lymphocytes, activated macrophages, activated NK cells, and cytokines in response to an antigen and is mediated by T-lymphocytes

Macrophages call in the lymphocytes (B-cells and T-cells) - these are mobilized to find the non-self invader (called an antigen):

•  T-cells - identify and eliminate antigens.

•  B-cells - produce specific antibodies (think of them as flags) to attach to a specific antigen to identify it as a marked target for destruction by cytotoxic T-cells(Natural killer T-cells / NKT). Note, these are distinct from Natural Killer (NK) cells of innate immunity;

•  Helper T-cells - signal B-cells to multiply to strengthen attack force;

•  Suppressor T-cells - down-regulate other I.S. responses;