Intro to Immunology Flashcards
What is plasma?
What remains from a blood sample after the erythrocytes (RBCs) and leukocytes (WBCs) have been removed. Plasma contains clotting factors, antibodies, complement proteins, etc..
What is serum?
a clear yellowish fluid that remains from a blood sample after it has been allowed to clot and all of the cells (RBCs and WBCs) have been removed. Serum contains antibodies and complement proteins.
What is a titer?
a term that refers to the concentration of antibodies that have specificity for a particular antigen
What is inflammation?
part of the body’s response to injury, and it consists of redness, heat swelling, and pain.
The suffix –itis means inflammation
What does the suffix –penia mean?
indicates a deficiency of something: e.g. neutropenia means that a patient has abnormally low numbers of neutrophils; leukopenia means that the patient has abnormally low numbers of white blood cells; etc.
What do the suffixes –cytosis and –philia mean?
indicate an elevated number of white cells in the peripheral blood. Elevated numbers of cells can be indicative of clinical conditions such as infection.
What are bands or band forms?
immature neutrophils that can be seen on a blood smear. During a serious bacterial infection, the body’s stores of neutrophils can be depleted, resulting in production of large numbers of new neutrophils in the bone marrow. The newly generated neutrophils in this case are released into the blood before they have matured and they have a characteristic appearance because their nuclei have not segmented yet.
What is the difference between the roles of the innate and acquired immune system?
The role of the innate immune system in a general sense, is to prevent or control infection while the acquired immune response is being generated so that the infected host (or patient) does not suffer too much infection-mediated damage. Once the acquired immune response is generated, it can clear the infection with high specificity and efficiency. Over the next few weeks, we will talk about each of the innate immune “responses” and the acquired immune responses, as well as the mechanisms that result in removal of the infectious agent from the host’s tissues.
What are some of the key characteristics of the innate immune system?
In all people, the innate immune response is essentially the same.
It provides protection from pathogenic insult starting with initial encounter, and it continues to control an infection for about the first 4-5 days post exposure (rapid response).
The specificities of the innate immune system are fixed and very limited. This means that the specificities of innate responses are essentially identical in all immunocompetent hosts, and they don’t change in response to any specific infection. These specificities recognize only general features of a pathogen, such as LPS (which is found on all gram-negative bacteria).
The innate immune response remains constant over the course of an infection.
The innate immune responses will always be the same each time a specific pathogen is encountered.
What are some of the key characteristics of the acquired immune system?
Adaptive responses are not preformed, and generating these responses takes some time (at least a week after initial exposure to the pathogen).
The acquired response is highly variable. The effector cells of adaptive responses (lymphocytes) have a huge array of possible specificities that are highly specific for potentially any product made by any pathogen.
The adaptive immune response also improves over the course of the immune response.
The adaptive immune response involves clonal expansion and memory of the response that makes it much more effective upon any additional encounter with that specific pathogen in the future.
Finally, it is important to note that some of the effector mechanisms that are employed by the acquired immune system are dependent on components of the innate immune system.
T or F. The innate immune system has a limited array of specificities that are limited mostly to common determinants of pathogens.
T. These specificities are determined by what are known as pattern recognition receptors (or PRRs). These receptors recognize what we will call PAMPS, or pathogen-associated molecular patterns.
In contrast, the cells of the acquired immune system (B cells and T cells) express highly specific receptors that recognize discreet structures of a particular pathogen. The receptors on a single B or T cell are all the same and all cells are unique
Overview of the complement cascade.
there are a series of proteins found in the serum and in the extravascular spaces of the body that are expressed at constitutive levels at all times (whether an infection has occurred or not). Each of these pathways can be initiated innately, and once they are initiated, there are three end products that help to control or eliminate infectious agents (primarily bacterial or even fungal agents):
(1) inflammatory mediators called anaphylatoxins,
(2) opsonins (or permanently attached tags that mark the pathogen for uptake and destruction by neutrophils and macrophages), and
(3) the membrane attack complex or MAC (a structure that inserts into bacterial outer envelopes, resulting in death of the bacterium).
What are primary lymph tissues responsible for? What are they?
these are where all immune cells are generated. These are the bone marrow (where all precursor immune cells are generated) and the thymus (where thymocytes migrate to and undergo their development into mature naïve T cells).
The secondary lymphoid tissues are where all acquired immune responses are initiated.
How are immune cells derived in bone marrow? (The immune cascade)
There is a single progenitor cell, called the hematopoietic stem cell that gives rise to three progenitor cells:
- The common erythroid/megakaryocyte progenitor gives rise to erythrocytes (red blood cells) and megakaryocytes. Megakaryocytes give rise to platelets, which (as you probably know) are critical for clotting.
- The common myeloid progenitor gives rise to most of the purely innate immune cells. These include the granulocytes (neutrophils, eosinophils, and basophils), dendritic cells, monocyte/macrophages, and mast cells.
- The common lymphoid progenitor gives rise to one purely innate cell type (NK cells) as well as the two cells that comprise the adaptive immune system (B cells and T cells) that are collectively known as lymphocytes.
What is the role of erthrycytes?
RBCs have an important role in the clearance of immune complexes from the circulation,
What is the role of megakaryocytes?
megakaryocytes produce platelets, or thrombocytes.
What are Neutrophils?
purely innate cells that recognize pathogens via their pattern recognition receptors, signaling them to engulf and kill the microbe.
The primary role of these cells is to control bacterial and fungal infections
These cells are considered granulocytes. This term reflects that they have a large number of cytoplasmic granules (that are critical to their function) that are easily visible upon staining. They are also often referred to as polymorphonuclear cells, or PMNs, because of their multi-lobed nucleus.
NOT anitgen presenting cells
What is a band cell?
Bands are immature neutrophils that can be distinguished from mature neutrophils by their nucleus that is not yet segmented.
When are band cells common?
During bacterial infections, neutrophils are essentially the marines of the immune system. Large numbers of them move into the infected tissue and take up bacteria and kill them. However, they are essentially kamikazes and have a short lifespan. If the bacterial infection is serious enough, the body’s stores of mature neutrophils will be exhausted and new neutrophils will be generated in the bone marrow and then released into the bloodstream as immature cells (bands). The presence of bands can help a physician to diagnose a condition as a bacterial infection.
What is the precursor to a macrophage?
a monocyte. They do not really have any function until they leave the vasculature, move into tissues and become mature macrophages.
What are macrophages?
the mature version of a monocyte that has entered and patrols extravascular tissues. They are multifunctional cells that have important roles in the innate immune response: namely, to recognize, engulf, and destroy potential pathogens that it recognizes via its many pattern recognition receptors.
Macrophages also have complement receptors that allow them to recognize foreign material that has been labeled with complement opsonins. When this occurs, they take up and destroy the material.
Do macrophages also participate in acquired immune response?
Yes, They are one of the three professional antigen presenting cell types (plus dendritic and B cells) that can activate naïve T cells, and they express antibody Fc receptors that allow them to be bridged into an acquired immune response.
What are eosinophils?
Eosinophils are another of the granulocytes. The primary role of these cells is to control PARASITE infections. Their granules contain inflammatory mediators and compounds that are toxic to parasites. Purely Innate immune response cell
They also have IgE receptors on their surface.
What are basophils?
The last of the granulocytes are the basophils. Purely innate immune cell response. These are the least abundant granulocyte, and their function remains somewhat un-defined. Have IgE receptors on their surface.
They probably have similar effector mechanisms to eosinophils.
What are mast cells?
Purely innate immune response cells. Are involved in protection against parasite pathogens. Their granules contain very potent inflammatory mediators, and they also have high affinity IgE antibody receptors on their surface.
The main focus our our discussions of these cells will relate to their role in immediate-type hypersensitivity responses like hay fever, asthma, and systemic anaphylaxis.
This is a very important cell type for you to know about because of the extreme clinical condition that results when they are activated in a systemic fashion.
What is mastocytosis?
A rare condition in which patients have an overabundance of mast cells.
