Innate to Adaptive Immunity, Blood cell types Flashcards Preview

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Define: Pattern-recognition receptor, pathogen-associated molecular pattern, Toll-like receptor, and recognize their abbreviations.

Most cells in the body have some pattern-recognition receptors, PRR, on their surface or on inner membranes.Among these are at least 10 “Toll-like receptors,” TLR, Each TLR can recognize a foreign molecular structure that we humans don’t have.Foreign molecular structures called pathogen-associated molecular patterns (PAMP);Stress or damage indicators expressed by body cells, sometimes called damage-associated molecular patterns (DAMP)


List some common foreign patterns recognized by TLR.

TLR4 binds lipopolysaccharide (part of the cell wall of Gram-negative bacteria); TLR2 binds peptidoglycan (Gram-positive bacteria); and TLR3 binds double-stranded RNA, which many viruses make. Also sees things released from corrupted cells. Can recognize Pamps and Damps!!! Both trigger inflammation.


Identify the final transcription factor that is most commonly activated in inflammation. How is it activated? What is inflammation?

When TLR—for example on blood vessel cells, or white blood cells passing by near an infected wound—bind the foreign pattern, signaling cascades are activated that lead to the expression of factors that cause inflammation. Inflammation is defined for our purposes as increased blood vessel diameter, stickiness, and leakiness, with an efflux of fluid and phagocytic white blood cells into the tissues. The net effect is to activate the mother of all inflammatory transcription factors, NF-κB. Causes the release of all sorts of factors that cause an inflammatory response. When NFKB moves to the nucleus, the cell begins to release chemokines and cytokines.


Define cytokine and chemokine.

The factors made by the PAMP-stimulated cell are called cytokines and chemokines.Chemokines (Greek -kinos, movement) are a family of small cytokines, or proteins secreted by cells. Their name is derived from their ability to induce directed chemotaxis in nearby responsive cells; they are chemotactic cytokines. When these are released, WBC head towards it because they like areas of high concentration, like they like pizza.Cytokines (Greek cyto-, cell; and -kinos, movement) are small cell-signaling protein molecules that are secreted by the glial cells of the nervous system and by numerous cells of the immune system and are a category of signaling molecules used extensively in intercellular communication. Cytokines can be classified as proteins, peptides, or glycoproteins; the term cytokine" encompasses a large and diverse family of regulators produced throughout the body by cells of diverse embryological origin. Generally help inflammation."


Describe the function of the innate immune response.

It provides a barrier to the outside world. You are born with it. It can’t adapt to new things. It is a ready made set of tools that helps us recognize things that don’t belong. It is crucial to know when something dangerous has come into the body, and mobilize defenses against it.Innate is the fire that lights the fuse of the bomb that is the adaptive immune system.


Name the cell that forms the bridge between innate and adaptive immunity.

There are special phagocytic cells at the interfaces between the body and the world—skin, lung, mucous membranes—called dendritic cells (DC) because their membranes are highly branched.At a wound site, immature DC get activated by the soup of cytokines and chemokines, and take up anything they can, including foreign molecules derived from the invaders. Dendritic cells are the best phagocytic cells ever. It jumps into the lymph system and travels to a lymph node. This is where the adaptive immune system lives (T and B cells). During its journey, it becomes the best presenting cell and the best cell to stimulate the adaptive immune system.


Discuss in principle the role T cells and B cells play in immunity.

Their strategies are the same - the recognition and removal of foreign substances.Their tactics, however, are quite different. The reason for this has to do with the jobs each population has been assigned.B cells protect the extracellular spaces of the body - the tissue fluids, blood, secretions - by releasing antibody into these fluids.T cells themselves survey the surfaces of the body’s cells, looking for ones that have parasites within them or that are dangerously changed or mutated.


Distinguish briefly the chief functions of the 5 immunoglobulin classes.

IgG: Two adjacent IgG molecules, binding an antigen such as a bacterium, cooperate to activate complement, a system of proteins that enhances inflammation and pathogen destructionIgM: It’s even better at activating complement than is IgG, and is the first antibody type to appear in the blood after exposure to a new antigen.IgD is a form of antibody inserted into B cell membranes as their antigen receptor.IgA is the most important class of antibody in the secretions like saliva, tears, genitourinary, intestinal fluids, and milk. It plays an important role as the first line of defense against microorganisms trying to gain access to the body through the mucous membranes.IgE is designed to attach to mast cells in tissues. It is involved in allergic responses, but the real role of IgE is in resistance to parasites like worms.


Give examples of immunopathology.

Type I immunopathology: immediate hypersensitivity, is seen in patients who make too much IgE to an environmental antigen, which is often innocuous like a pollen or food. About 10% of the population has allergic symptoms.Type II immunopathology is autoimmunity due to antibodies which react against self.Type III immunopathology can occur whenever someone makes antibody against a soluble antigen.Type IV immunopathology is T cell mediated, and can be autoimmune, or more commonly innocent bystander injury.


Understand the general principle of the Wright-Giemsa stain: describe how acidic components in the cell will stain and what the main acidic components of the cell are and how basic components in the cell will stain and what the main basic components of the cell are.

The usual stain for peripheral smears (and bone marrow aspirate smears) is a Wright-Giemsa stain.To perform this stain a dried smear is fixed with methanol and then immersed in solutions containing combinations of eosin and methylene blue (and chemical derivatives of methylene blue).The eosin stains basic cellular elements (e.g. hemoglobin, other basic proteins (often in the cytoplasm), some cytoplasmic granules such as those present in eosinophils) an orange-red color.Methylene blue imparts a bluish-purple color to acidic cellular elements. RNA and DNA are the primary acidic elements in the cell, although other elements such as basophil granules and the cytoplasm of mature lymphocytes and monocytes also stain blue.Thus often, but not invariably, if a structure or area has a bluish-purple color to a structure it is likely to contain nucleic acid – e.g. the nucleus. Similarly if a structure or area has an orange-red color it often, although not invariably, contains protein – e.g. the cytoplasm of a mature cell.


Recognize the types of white cells that may normally be found in the peripheral blood.

The nucleated cells are the white cells which can be further subdivided into lymphocytes (T-cells, B-cells, NK cells) granulocytes (neutrophils, eosinophils, and basophils), and monocytes.


What is a white blood cell differential?What is the the absolute white blood cell count?Given the white blood cell differential and the total white blood cell count, be able to calculate the absolute count of a particular white blood cell type.

The white blood cell differential is simply determining what percentage of white cells in an individual are neutrophils, what percentage are lymphocytes, what percentage are monocytes, what percentage are eosinophils, and what percentage are basophils.The WBC is the total number of white cells (neutrophils, lymphocytes, monocytes, eosinophils, and basophils) in a microliter or liter of whole blood.To determine the absolute number of neutrophils it is necessary to know the WBC and determine what fraction of that number is neutrophils. Use multiplication.


Give a range for the absolute counts of the various white blood cells in a normal adult. Describe how the white cell counts fluctuate with age.

Basophil: 0-200/µLEosinophil: 0-400/µLMonocyte: 200-900/µLLymphocyte: 1,000-4,800/µLNeutrophil: 2,000-8,000/µLThere is variability of the WBC in the pediatric years, but not in normal adults. Additionally, the WBC does not change significantly with age. A ballpark range to keep in mind for adults is 5,000 to 10,000/μL.


Describe the shape of a red blood cell and the significance of this shape.

The erythrocyte is 7 to 8 µm in diameter. The cell is a biconcave-shaped disc; this shape increases surface area so that O2 and CO2 transfer to hemoglobin is facilitated. The biconcavities create the central area of pallor that is seen in erythrocytes in air-dried, Wright-Giemsa-stained smears. The cytoplasm of a Wright-stained erythrocyte is orange-red in color.


Explain the difference between a red blood cell and a reticulocyte.Describe how a reticulocyte count is performed.

Reticulocytes are young, anucleate red cells that retain RNA, ribosomes and other organelles that are enable ongoing production of hemoglobin.Normally reticulocytes are retained in the bone marrow for around three to four days before being released into the peripheral blood. In the peripheral blood reticulocytes circulate for one to two days gradually losing retained RNA and other organelles while accumulating a full complement of hemoglobin. When all of the retained RNA and protein-making machinery is lost the reticulocyte becomes a mature red blood cell. Gives an indication of bone marrow function in anemia patients.A reticulocyte count can be performed manually by microscopically examining 1000 red cells on a supravitally stained peripheral smear and determining what percent of these cells are reticulocytes. Most of your modern hematology analyzers will perform an automated reticulocyte count


Give a range for the red blood cell count in a normal adult man and a normal adult woman.Describe how the red blood cell count fluctuates with age.

Men 4.60-6.20 x 1012/LWomen 4.20-5.40 x 10^12/LPhysiologic variables that affect the RBC include age (starts high when young, dips, returns higher), sex (men have a larger RBC than women), and geographic location (RBC is greater at higher altitudes than lower altitudes). 


Be able to recognize a platelet in a peripheral blood smear.

These small anucleate cells are 2 to 4 µm in diameter, and appear granular and purplish.


What kind of cell is on the far left and far right?

A reticulocyte! Remember, it has RNA, ribosomes, and other organelles that may stain blue/purple. 


What kind of cells are these?

Red blood cells.  Note the central area of pallor.  What is the shape of this cell important for?(You better get used to the surprise pimping. Question in the answer? Yep.)


Give a range for the platelet count in a normal adult. Describe how the platelet count fluctuates with age.

150,000 to 400,000/µL (microliters) is a ballpark figure for the platelet count in a normal individual. Does not vary with age or sex.


What kinds of cells are these (not the RBC)?

Neutrophils. They neutralize bacteria. These cells are granulocytes and are also known as segmented neutrophils, and polymorphonuclear leukocytes. The neutrophil has a diameter of 12-15 μm on a peripheral blood smear. The nuclear chromatin is coarsely clumped. The nucleus is segmented into two to five (usually three) distinct lobes that are connected by thin chromatin strands.


What are these? 

Bands: The most mature immature neutrophil. Increases in the peripheral blood in response to infection of other stress.


What are the white cells in this picture?

Eosinophils. These cells are the second most abundant granulocyte in the peripheral blood. The mature eosinophil is around 13 μm in diameter. The cytoplasm contains large orange-red (eosinophilic) granules. The nucleus contains heavily condensed chromatin and is segmented into usually two round to oval lobes.


What is the white cell in this picture?

A basophil. These cells are the least abundant granulocyte, and, indeed, the least abundant of all white cells in the peripheral blood. The mature basophil is 10 μm in diameter. It contains a lobular but non-segmented nucleus. The nucleus is usually obscure by numerous blue-purple (basophilic) granules.


What is the white cell in this picture?

Monocyte. With a diameter of 15 to 18 μm, this cell is the largest in the peripheral blood. The nucleus assumes a variety of shapes including reniform and even band-like. The chromatin does not have the clumpy appearance such as in the band or segmented neutrophil. The cytoplasm is bluish with an opaque ground-glass appearance. Red-purple (azurophilic) granules are scattered through the cytoplasm, but are nowhere near as abundant as in the neutrophil.


What are the white cells in this picture?

Lower left = segmented neutrophil, upper right:lymphocyteLymphocyte: Two types of lymphocyte may be encountered in the peripheral blood of a “normal” person. The “small round lymphocytes” are 6 to 9 μm in diameter with round or slightly indented nuclei. The nuclei contain dense clumpy chromatin. A thin rim of blue cytoplasm surrounds the nucleus. There are also larger lymphocytes that range from 12 to 15 μM in diameter. (LGL) is less abundant. The cells have large, somewhat irregularly shaped nuclei with condensed chromatin that is less clumped than the chromatin of small round lymphocytes. The cytoplasm is more abundant, blue, and may contain 10 to 20 red-purple (azurophilic) granules. This cell is sometimes mistaken for a monocyte and vice versa.