Sexually transmitted diseases are a common problem among young people in the United States. One of the more common diseases is caused by the bacterium Neisseria gonorrhoeae, which leads to inflammation and purulent discharge in the male and female reproductive tracts.

The bacterium has a number of systems to evade host defenses. Upon infection, it uses pili to adhere to host epithelium. The bacterium also uses an enzyme, gonococcal sialyltransferase, to transfer a sialyic acid residue to a gonococcal surface lipooligosaccharide (LOS). A depiction of this can be seen in Figure 1. The sialyic acid residue mimics the protective capsule found on other bacterial species.

Once infection is established, Neisseria preferentially infects columnar epithelial cells in the female reproductive tract, and leads to a loss of cilia on these cells. Damage to the reproductive tract can result in pelvic inflammatory disease, which can complicate pregnancies later in the life of the woman.

In an immune response to an organism like Neisseria, humans will often make use of antbodies. What is true of antibodies?

One component of the immune system is the neutrophil, a professional phagocyte that consumes invading cells. The neutrophil is ferried to the site of infection via the blood as pre-neutrophils, or monocytes, ready to differentiate as needed to defend their host.

In order to leave the blood and migrate to the tissues, where infection is active, the monocyte undergoes a process called diapedesis. Diapedesis is a process of extravasation, where the monocyte leaves the circulation by moving in between endothelial cells, enters the tissue, and matures into a neutrophil.

Diapedesis is mediated by a class of proteins called selectins, present on the monocyte membrane and the endothelium. These selectins interact, attract the monocyte to the endothelium, and allow the monocytes to roll along the endothelium until they are able to complete diapedesis by leaving the vasculature and entering the tissues.

The image below shows monocytes moving in the blood vessel, "rolling" along the vessel wall, and eventually leaving the vessel to migrate to the site of infection.

Neutrophils are able to respond to the constant region of antibodies that coat foreign invaders. The neutrophil recognizes these antibodies, and ingests the pathogen they coated. Which of the following is true of antibodies?

Cholera is a disease caused by vibrio cholerae, a bacteria which enters the body through the digestive tract. The bacteria is absorbed by the small intestine and enters the blood stream. Which of the following antibodies would be most effective at preventing cholera?

A patient is admitted to the hospital needing a blood transfusion. The patient has type A negative blood. Which of the following is true?

Which part of the antibody recognizes the antigen?

Type 1 diabetes is a well-understood autoimmune disease. Autoimmune diseases result from an immune system-mediated attack on one’s own body tissues. In normal development, an organ called the thymus introduces immune cells to the body’s normal proteins. This process is called negative selection, as those immune cells that recognize normal proteins are deleted. If cells evade this process, those that recognize normal proteins enter into circulation, where they can attack body tissues. The thymus is also important for activating T-cells that recognize foreign proteins.

As the figure below shows, immune cells typically originate in the bone marrow. Some immune cells, called T-cells, then go to the thymus for negative selection. Those that survive negative selection, enter into general circulation to fight infection. Other cells, called B-cells, directly enter general circulation from the bone marrow. It is a breakdown in this carefully orchestrated process that leads to autoimmune disease, such as type 1 diabetes.

There are many ways that the body's immune system can attack its own tissues in autoimmune disease. A scientist discovers that in type 1 diabetes, antibodies play a key role in attracting lymphocytes to normal tissue, which is then damaged or destroyed. What kinds of cells typically produce antibodies?

I. T-cells

II. B-cells

III. Macrophages

Which of the following cell types secretes antibodies?

Major histocompatibility complex (MHC) I molecules primarily display antigens derived from what type of pathogen?

Major histocompatibility complex (MHC) II molecules are responsible for displaying antigens from what invading pathogen?

Blood types are designated A, B, AB, and O depending on the glycoprotein presented on the surface of the red blood cells. If a person has glycoproteins  and . What is the person's blood type?