sciencenote:

Superantigens (SAgs) are a class of antigens which cause non-specific activation of T-cells resulting in oligoclonal T cell activation and massive cytokine release. SAgs can be produced by pathogenic microbes (including viruses, mycoplasma, and bacteria) as a defense mechanism against the immune system.Compared to a normal antigen-induced T-cell response where .001-.0001% of the body’s T-cells are activated, these SAgs are capable of activating up to 20% of the body’s T-cells.^{[citation needed]} Furthermore, Anti-CD3 and Anti-CD28Antibodies (CD28-SuperMAB) have also shown to be highly potent superantigens (and can activate up to 100% of T cells).

(via molecularlifesciences)

medicinenotes:

Eosinophils: changing perspectives in health and disease

Helene F. Rosenberg, Kimberly D. Dyer & Paul S. Foster

Abstract

Eosinophils have been traditionally perceived as terminally differentiated cytotoxic effector cells. Recent studies have profoundly altered this simplistic view of eosinophils and their function. New insights into the molecular pathways that control the development, trafficking and degranulation of eosinophils have improved our understanding of the immunomodulatory functions of these cells and their roles in promoting homeostasis. Likewise, recent developments have generated a more sophisticated view of how eosinophils contribute to the pathogenesis of different diseases, including asthma and primary hypereosinophilic syndromes, and have also provided us with a more complete appreciation of the activities of these cells during parasitic infection.

(via sciencenote)

afracturedreality:

A macrophage (pale brown) interacts with Borrelia cells (blue), the spirochete bacteria that cause Lyme disease. Although the outer membrane of Borreliacontains a strong antigen, the OspC protein, the bacterium successfully evades the human immune system by hiding out in places less accessible to immune cells, such as the central nervous system.

By eye of science/Nicole Ottawa and Oliver Meckes

sciencephotolibrary:

Cell infected with HIV. Coloured scanning electron micrograph (SEM) of HIV particles (red) budding from the membrane of a host cell. HIV (human immunodeficiency virus) attacks CD4+ T-lymphocytes (specialised white blood cells), which are crucial in the body’s immune system. It enters the cell and makes many copies of itself, which then destroy the cell as they emerge through its membrane. This severely weakens the immune system, causing AIDS (acquired immunodeficiency syndrome).

Credit: THOMAS DEERINCK, NCMIR/SCIENCE PHOTO LIBRARY

(via infectiousdiseases)

thephilosophiles:

emp of immune cells attacking a parasite by David Pérez-Morga

bpod-mrc:

Munching Macrophages

These bead-like strings of bacteria (viewed by electron microscopy) are suffering a gruesome end. They are being eaten alive as they sit atop a macrophage, a white blood cell that is our primary defence against bacterial infection. After digesting the invader, the macrophage then moves fragments of broken-down bacteria to its surface. This signals other cells in the immune system to make proteins, which also attack the infection. However, the process is not fool proof. Some pathogens have evolved to evade digestion and reproduce inside the macrophage. Tuberculosis and leishmaniasis, two of the biggest killers in the developing world, both use this trick to duck under the immune system’s radar.

Written by Alice Lighton

—

• Gordon Beakes
• University of Newcastle upon Tyne
• Image courtesy Centre for Bioscience, the Higher Education Academy, ImageBank

(via infectiousdiseases)

crystilogic:

Display of Peptides by Class I MHC: or, the Body as Surveillance State, from my pathology notes (2012). The curved line at the top is the cell membrane.

Your cells chop up the proteins inside them and hold the pieces out for inspection on little flags—MHC proteins—that stick out through the cell membrane. Cells called lymphocytes—T cells, B cells, the ominously named NK ‘Natural Killer’ cells—rub up against these little flags to see what’s up. The T and B cells are looking for things that don’t belong, things that could be pieces of a virus. The NK cells are looking for cells that seem weirdly stressed or are trying to hide their MHC flags. Suspicious-looking cells are killed or made to kill themselves.

But there’s another, lovelier side to the MHC proteins. Evolution is about death, but for at least a billion years it’s also been about sex. (See also: Aphrodite and Ares, lovers.) There are hundreds of variants of the MHC protein flags, and it seems that people who have different kinds are more into the smell of each other’s sweat, and possibly piss as well.

(via fyeahmedlab)

short-straw:

This photo is a molecular representation of an antibody. Antibodies are proteins produced by B cells of the immune system. Initially, their function was defined as distinguishing self antigens from non-self antigens. However, this definition was refined to describe their function as distinguishing harmful foreign antigens.

Each individual produces millions of antibodies and each of these has two arms (upper part of photo) which are highly specific against a particular type of antigen. This therefore equips the immune system with a defence that is both broad and specific. The arm pictured in the bottom end of this photo is able to attach itself to cells of the immune system, allowing them to come closer to pathogens and triggering them to defend the body.

Antibodies can neutralize toxins, enhance phagocytosis of pathogens by opsonization, activate components of the complement system which is involved in defence and much more. In autoimmune diseases, antibodies play a role by recognizing self antigens (eg the fatty insulation around our neurons) or non-harmful, non-self/foreign antigens (eg pollen). This leads to the inappropriate activation of the immune system.

This photo is a courtesy of science photo library

(via fyeahmedlab)

decaturjim:

Origin and differentiation of immune system cells

The human immunological system comprises several organs including the spleen, thymus, lymph nodes and bone marrow, each contributing to the development of immune cells.

Shown above is a nice overview of these immune cells in terms of the stem cell origin and subsequent differentiation.