Immune System

This is from chapter 43. You can do the reading there if you find that helpful. Here is a primer on the cells of the immune system that I recommend to get a good overview. Work though the cells of the immune system. When we get together next, we will spend some time playing a couple of games. You don't have to work on that now.

We will start with this
game and also play this one here.

Here is the slideshow from yesterday and today.

Here is a nice overview slide of the adaptive response:
Adaptive Overview

Barriers such as skin and mucus, tears etc. form initial barrier

Innate Immunity:

Don't forget that your first line of defense is the barrier you have.
Cell and biochemical defenses against pathogens. These have four main roles:
  1. First responders attack intruders (some specific for particular types of pathogens using recognition receptors).
  2. Cells release pro-inflammatory signal molecules that attract other immune cells to the area (both more innate immunity cells and adaptive cells)
  3. Present antigens for adaptive immunity to surveil
  4. Following adaptation of B-cells and antibody production, some components of innate immunity are targeted more specifically to pathogen by the antibodies

Cells (really just some of them) The figure shows how red blood cell and thrombocytes (for blood-clot formation) derive from the same progenitor cells as the immune system. You don't have to memorize the details. Know B cells T cells (both types) and Macrophages (antigen presenting cells) like in the game.
Macrophage (big mouth). Know this one. Gobble pathogens up, present antigens to adaptive cells in the MHC receptor and release pro-inflammatory signal molecules (other antigen presenting cells include dendritic cells).
Weird-shaped nucleus cells (OK, that's not the official name. They are called "polymorphonuclear cells," which essentially means the same thing). They, along with mast cells, are the main source of the pro-inflammatory signals. They all have slightly different jobs and include the basophil (likes basic stain); neutrophil (neutral pH stain) and Eosinophil (likes acid stain). You wouldn't need to know what each of these do. But, you could get a figure that has them in it.

Mast Cells are probably the worst offender, along with basophils and eosinophils. Probably good to know Mast cells. They are the underlying inducers of allergies and anaphylaxis. Secrete lots of pro-inflammatory signals. Extra information: Eosinophils in particular collect special antibodies made by certain B cells called IgE, which they then use to attack all the multicellular parasites you have, like worms and such. If you don't have worms, they are fond of attacking pollen grains, etc.

Natural-killer (NK) cells. You should know these. Come from the same line as the cells of the adaptive immune system. Activated by macrophage signals, identify infected cells in the body and kill them

Adaptive Immunity

We will talk more about this later.
You should know all of this unless noted.
T-cells (thymus) and B-cells (bone-marrow).
B cells are the ones that make antibodies (also known as B-cell receptor prior to class switching…more on that later).
Both T and B cells undergo "somatic rearrangement" of their DNA to express one and only one T-cell receptor or B-cell receptor. The enzymes that carry out the splicing of the DNA are called "Rag-1" and "Rag-2." (Recombination Activation Gene 1 and 2). This is known as "V(D)J recombination and it generates a different antibody
for each B cell line you have. A very similar thing happens in the T-cells. During maturation of B cells, one V (variable) region, one D region (diversity) and one J region (junctional) are brought together and linked to the Constant region to make the heavy chain of the antibody. The light leaves out the "D" and the C region.
The "antigen-combining site" is at the amino (NH2) terminus of each chain. This is what allows the antibody to bind the antigen.

Cytotoxic T-cells (also called "CD8-positive T cells") identify infected cells and other targets based on specific recognition by their T-cell receptor and secrete chemicals to kill them. They make their receptor through a similar process as the B cell (somatic recombination).

Helper T Cells
These are critical for the full response (and also the target of HIV. They have a T-cell receptor as does the killer. But, they look for B cells that have been stimulated by the same antigen. If they find one, they initiate the highly active response in the B cell in which the receptor evolves into an even more specific antibody. Eventually, the highly activated B cells undergo "class switching," which just means they initiate an alternative RNA splice that gets rid of the membrane-bound creation of the antibody and start secreting it as part of the soluble or "Humoral" response.

The main use of the antibody is then to target components of the innate immunity more specifically toward the pathogen.

I think that's the important stuff. Remember, I sugar wcan show you figures of things I haven't discussed, necessarily. Also, go over the terminology on the online quiz.