The cells of the adaptive immune system attack foreign pathogens by producing proteins, such as antibodies, that use a lock-and-key mechanism to recognize pathogenic antigens, or molecules that can elicit an immune response (Figure 1). In order to defend our bodies against the millions of different pathogens that could harm us, the adaptive immune system … Continue reading Somatic Recombination
Adaptive immune cells, like T cells, play a critical role in protecting our bodies against invading pathogens, a task that relies upon their ability to recognize pathogens as foreign, or ‘non-self’. This begs the question, though, of how adaptive immune cells distinguish between self and non-self. How is it that T cells know to attack … Continue reading Positive and Negative Selection of T Cells
T cell receptors are required for the activation, regulation, and function of T cells. TCRs are generated by the random joining of gene segments in the TCR gene loci. TCR assembly occurs through a process called V(D)J recombination, so named for the gene segments joined to make the β–chain of the TCR and the heavy … Continue reading How-to make: a T cell receptor (the simpler version)
The microbiome is a group of microorganisms living in a particular environment (for example, the human gut). These microorganisms are not just limited to bacteria: viruses, fungi, and archaea can also be present. Microbiomes are not limited to humans or even to mammals--insects and plants have microbiomes that are crucial for their health. Microbiomes are … Continue reading The Mighty, Mighty Microbiome
Central Tolerance Central tolerance refers to the negative selection step in T cell differentiation. It occurs in the thymus, where newly recombined T cell receptors are screened against a bevy of self-antigens and overactive clones are deleted. See Positive and Negative Selection of T Cells. Clonal Deletion - T cells that recombine a TCR with a … Continue reading Regulating “self” versus “non-self” – T cell tolerance mechanisms
Autoimmunity is a blanket term describing pathologies where the immune system attacks its host body. The typical paradigm is that the immune system protects us from foreign invaders- pathogens looking for a niche to colonize. In autoimmune disease, the immune system mistakes our body’s tissues for a target- and harms them. Whether due to a … Continue reading Friendly Fire – an introduction to autoimmune disease
Phagocytosis is the process of a cell ingesting another cell or particle. It works by having the phagocytosing cell bind the desired target onto its surface and bringing it inward while it engulfs the target. This is a relatively simple mechanism that cells such as macrophages of the immune system can use to destroy foreign … Continue reading Neutralizing your enemies by eating them? Just an ordinary day in the life of the immune system!
The major histocompatibility complex (MHC) genes code for proteins which the immune system uses to identify cells and tissues in the body as “self” or “other”. MHC molecules ‘talk’ to T cells which patrol the body for foreign invaders or dangerously mutated cells. The MHC acts as a window into our cells. It presents snippets … Continue reading What is MHC and why does it matter?
Pathogens, including viruses and bacteria, have one primary goal: reproduction. Transmission is the movement of a pathogen from one host to the next. Infectious pathogens that cause disease have evolved to enhance the likelihood of transmission so that they can infect more hosts. For example, influenza virus and the measles virus are both highly contagious … Continue reading Vector-borne diseases: directions in transmission
Immune cells communicate with one another in many different ways, including through the production of cytokines. Cytokines are proteins that cells expel, or secrete, that can travel to other cells in the body, bind to receptor proteins on the cell surface, and relay a message. One important class of cytokines is interferons (IFNs), which play … Continue reading An introduction to interferons