Immunology

Immunity Is the body’s ability to recognize infectious disease causing organisms like bacteria and viruses, and protect the body from these organisms

Immunology Study of the system that fights infectious diseases

Smallpox Used to be one of the worldwide scourges But because of immunization, smallpox no longer exists in the world

Before 1979 Smallpox killed 80% of the children who contracted the virus, and about half the adults

Smallpox Since 1900, it is estimated that smallpox was responsible for 500 million deaths In 1967, the World Health Organization estimated that 15 million people contracted the disease and that two million people died in that year After successful vaccination campaign,eradication of smallpox was declared in December, 1979.

AIDS/HIV The hunt is on for a vaccine for HIV and AIDS Many millions will die from AIDS before then

How do immunizations work? Lock and key model

Antibodies are made by lymphocytes

Fab binds to antigen Fc binds to immune component

Antibodies bind to specific antigen Antigen – it can be any part of something, part of a bacteria, part of a virus that stimulates the immune system

Please do not confuse: Antigen (Ag) – any protein or structure that can stimulate an immune reaction Antibody (Ab) – Y shaped proteins that bind to antigens to mark them for phagocytosis. B lymphocytes make Antibodies

Antibody binds to antigen picture

Antibodies can be free in the blood. Antigen/Antibody complexes can signal digestion by macrophage Antigen Antibody complex picture

Antibodies can be attached to lymphocytes Ag/Ab complexes can signal the lymphocyte to reproduce making more of the same antibody Antigen Antibody complex picture

Immunization Now the body has a huge increase in the number of “receptors” that can activate the immune system in case of exposure to specific bacteria or viruses Antibody picture

Immunization So the next time the body is exposed to the specific bacteria or virus… There are already lots of antibodies to attack it

Immunity Immunity prevents infection by the increased ability for Ab to signal the destruction of the infectious organism

Serum SERUM is the liquid base of Blood It is mostly salt water

SERUM Contains small proteins called ANTIBODIES and COMPLEMENT Again antibodies are made by lymphocytes Complements are designed to attach to viruses and bacteria for phagocytosis

SERUM ANTIBODIES and COMPLEMENT attach to foreign substances such as bacteria to help the IMMUNE SYSTEM fight these substances.

SERUM Antibodies (Ab) are made by LYMPHOCYTES, a type of WHITE BLOOD CELL (WBC) Complement are proteins made by the LIVER Antibodies are very specific for antigens Complements are not specific for antigens

Plasma = Serum + Clotting Factors Clotting factors are proteins made by the LIVER Clotting factors make your blood clot - if you have no clotting factors, you would not stop bleeding from a tiny cut.

Blood Cells Red Blood Cells (RBC) - erythrocytes White Blood Cells (WBC) - leukocytes Platelets (Plt)

Blood Cells RBCs, WBCs, and Platelets are ALL made by the bone marrow During fetal development, the LIVER also makes these cells

Peripheral Blood Smear picture

WBCs – Neutrophils Neutrophils have many names Poly Morpho Nuclear Leukocytes Segmented Neutrophils (Segs) Granulocytes

WBCs – Neutrophils Neutrophils have many names: Poly Morpho

Neutrophils Picture

Granulocytes Picture

WBCs – Granulocytes There are other WBC Granulocytes besides Neutrophils - Eosinophils - Basophils

Eosinophils and Basophils Picture

Granulocytes The granulocytes contain granules These granules carry various kinds of poisons designed to kill infectious organisms That’s why people with neutropenia (too few neutrophils) are easily infected *penia – means too few

WBCs Non granulocytes WBCs that are not granulocytes are: Lymphocytes Monocytes

Lymphocyte and Monocyte Picture

Blood is made of: Substances that provide: Nutrient supply Waste removal Oxygen supply Carbon dioxide removal Stop bleeding IMMUNITY

Hematopoiesis How blood cells are made

Bone Marrow The cells we are about to see are only seen on bone marrow biopsy

The Stem Cell gives rise to 2 lines Myeloid Line - Erythrocytes (RBC) - Granulocytes - Neutrophils - Eosinophils - Basophils - Monocytes - Platelets

Lymphoid Line - Lymphocytes

Differentiation As the cells differentiate, they become different from the stem cells, and become the final product The more differentiated the cells are, the more they are like the final product

Stem Cell All of the cells of the blood begin as stem cells The stem cells divide rapidly, making not only more stem cells but cells that differentiate into their final form

Stem Cell Myeloid and Lymphoid Progenitor Picture

Lymphoid Line Picture

Plasma cell is a B lymphocyte that has been activated to make lots of antibodies

Myeloid Line picture

Granulocyte Stimulating Factor Filgrastim - Neupogen - G – CSF - this drug stimulates the body to make more granulocytes

Do not confuse G – CSF - Granulocyte Colony Stimulating Factor With: GM – CSF - Granulocyte Macrophage Colony Stimulating Factor

Body’s Defense Mechanism Everyday the body is exposed to numerous: - Bacteria - Viruses - Fungi - Parasites Our bodies are constantly fighting these organisms

Myeloid Line Neutrophils

Elevated White Count and Left Shift Seeing immature cells in the microscope we call it a left shift because in the old days laboratorians use the left hand to count using a cell counter

Reticulocytes – no nucleus - reticulated means a net-like pattern - still has parts of a nucleus Reticulocyte Count – to see if the bone marrow is making a normal amount of reticulocytes

Erythropoietin Erythropoietin is synthesized by the kidneys to stimulate the production of red blood cells

Epoetin Epoetin stimulates the production of red blood cells epoetin - Epogen - Procrit - EPO

Body’s Defense Mechanism Our bodies are really good at fighting off organisms which they encounter for the first time

Body’s Defense Mechanism Our bodies remember many of these organisms, so we can fight them even better in subsequent exposure

Immunity Immunity is the body’s ability to remember foreign substances, and attack them even better the next time

Immunity Immunity is NOT the developed tolerance to a drug, or a bacterial resistance to a drug

Picture of virus entering a healthy cell

Know that viral antigens are expressed on the surface of an infected cell The virus DNA/RNA go to the cell’s nucleus to replicate

Major Histocompatibility Complex Major – most important Histo – tissue Compatibility – how we get along Complex – not simple This is how immune cells identify self from foreign tissues

Cellular Immunity The macrophage expresses viral antigens on its surface with a MHC and secretes interleukin 1 or IL1

Interleukin is short for interleukocytokines Inter – between Leuko – white Cyto – cell Kine – communication

Interleukocytokines are how white cells communicate with each other

Interleukin 1 is how the macrophage calls for help IL1 attracts other macrophages IL1 also attracts other T helper cells T helper cells (CD4 cells) are a type of lymphocytes

Cellular Immunity So when our Macrophage has expressed Viral Antigen on MHC it calls for help Using IL1

T helper to the rescue IL1 T helper = TH = CD4

IL2 in T helper cell

Review Macrophage ingests the microbial product Presents the antigen Major Histocompatibility Complex Secretes IL1 T cell activation T helper lymphocyte TH = CD4 T helper cells identify antigen presentation Secretes IL2

Interleukins There are many interleukins It is important that you know that interleukins are how various white cells communicate Interleukins are also used as drugs

Interleukins and Interferons Interferons “interfere” with a virus ability to replicate it’s DNA/RNA

Interleukins and interferons Naturally occuring substances

Humoral Immunity Antibodies recognizing things in the bloodstream

Epitope – the part of an antigen molecule to which an antibody attaches itself

Humoral Immunity B cell exposure to antigen causes B cells to make antibodies

These antibodies stick to the specific antigen to mark or opsonize the antigen to make it easier to be attacked by granulocytes and monocytes

Gammaglobulins – class of plasma proteins composed almost entirely of immunoglobulins (Igs), the proteins that functions as antibodies

What is immunology? The production of immunoglobulins (antibodies) as a reaction of the human body when infected with an agent.

Immunoglobulins Glycoprotein molecules that are produced by plasma cells in response to an immunogen and which function as antibodies

Each immunoglobulin actually binds to a specific antigenic determinant Antigen binding by antibodies is the primary function of antibodies and can result in protection of the host

Different immunoglobulins IgG is the major Ig in extra vascular spaces Placental transfer – IgG is the only class of Ig that crosses the placenta 75% of total Ig’s

IgM IgM is the first Ig to be made by the fetus and the first Ig to be made by virgin B cells when stimulated by antigen Pentameric structure therefore IgM is a good complement fixing antibody Third most common Ig

IgA Second most common Ig It is a major class in Ig secretions such as tears, saliva, mucus Therefore, it is important in local (humoral) immunity

Other immunoglobulins IgE monomer with extra domain in the constant region least common Ig involved in allergic reactions IgE also plays a role in parasitic helminth diseases does not fix complement For Internal Use Only

IgD monomer low levels in serum uncertain role does not fix complement

Immunoreaction primary humoral immune response to an antigen: following exposure, IgM is the first antibody to appear followed by a much higher titre of IgG

Criteria for diagnosing primary Infection Seroconversion: changing from a previously antibody (Ab) negative status (seronegative) to a positive status (seropositive). Negative IgM & IgG do not exclude exposure to antigen (incubation time).

Presence of IgM: - offers rapid diagnosis - might be negative at convalescent phase

Presence of IgG: - significant rise between acute and convalescent (recovery) phase

- sharp rise of IgG - low or absent IgM

Screening population: - IgG present at acute & recovery phase and will remain detectable for mainy years, even for life time

Affinity: - Ab affinity is the strength of the reaction between a single antigenic determinant and a single combining site on the antibody …. in other words: the degree of match between Ag & Ab

Avidity: the eagerness of the Ab to match with an Ag - avidity is more than the sum of the individual affinities - the older the infection, the higher the avidity - the higher the avidity, the stronger the Ag-Ab binding

IgG Avidity Avidity increases with the maturation of the immune response For Internal Use Only

Polyclonal and monoclonal Ab’s Polyclonal Ab’s: - each B-cell clone produces Ab specific for one particular Ag epitope - but serum Ab’s are produced as a response to complex Ag, therefore contains a mixture of Ab’s raised against different Ag epitopes - each cell clone produce Ab’s specific for one of the various epitopes of the Ag  this polyclonal response is advantageous for the immune system because it helps localization, phagocytosis, and complement mediated lysis of the Ag Monoclonal Ab’s: - derived from a single plasma cell and specific for one epitope - useful for in vitro & in vivo diagnostic products For Internal Use Only

Antigens Viruses – Bacteria - Parasites Bacteria:prokayotic organisms single-celled organisms able to reproduce by duplicating themselves responsive to antibiotics typical bacterium: rigid cell wall, thin rubbery cell membrane surrounding the cytoplasma, various shapes (coccus, rod, vibrion etc) contains all genetic information to copy itself – DNA in the chromosome plasmids: extra circular bits of DNA ribosomes: necessary for copying DNA some have flagella For Internal Use Only

Antigens Viruses – Bacteria - Parasites The biggest viruses are only as large as the tiniest bacteria. Virus: lives within a cell (intracellular) to survive and needs host cell for multiplication not responsive to antibiotics protection through vaccination (not for all viruses) envelope: outermost spiky layer protein coat core of genetic material: DNA or RNA For Internal Use Only

Antigens Viruses – Bacteria - Parasites Parasite: eukaryotic organisms lives in or on the living tissue of a host organism lives at the expense of the host parasitism = biological interaction between host and parasite Some parasites: Toxoplasma gondii Cryptosporidium parvum oocytes Giardia intestinalis For Internal Use Only

Infectious diseases Kits currently available for the detection of Ab’s against: TORCH panel: Toxoplasma gondii Rubella virus Cytomegalovirus (CMV) Epstein-Barr virus (EBV) Measles Mumps Herpes Simplex virus type 1 & 2 Varicella zoster virus (VZV) Helicobacter pylori Treponema pallidum (Syphilis) For Internal Use Only

Viruses: different families (1) HERPESVIRIDEA (DNA viruses) 8 human herpes types Alpha group HV-1 Herpes simplex 1 Fever blisters, encephalitis HV-2 Herpes simplex 2 Genital, meningitis/enecephalitis (newborns) HV-3 Varicella zoster Chicken pox, shingles Beta group HV-4 Cytomegalovirus Infectious mononucleosis, neonatal fatality Gamma group HV-5 Epstein-Barr virus Infectious mononucleosis, cancer (Lymphoma) Other HV-6 HBLV (human B-lymphotropic virus) B cells HV-7 T cells (CD4+) HV-8 Sarcoma, lymphoma For Internal Use Only

Vaccinations Aim is to prevent epidemics which caused many deaths in the past. Vaccines help the body produce antibodies  protection. Most common vaccines: MMR: measles, mumps & rubella IPV: inactivated poliovirus DTaP: diphetheria, tetanus & pertussis Varicella vaccine HBV & HAV: hepatitis A & B Influenza PCV: pneumococcal conjugate vaccine ………. Pipeline: hepatitis C, RSV, HIV, CMV, EBV, ….. Far future: HSV 1&2, adenovirus, toxoplasmose For Internal Use Only

Herpes Simplex 1 & 2 (1) both belonging to the Herpesviridea slight antigenic difference between HSV-1 and HSV-2 HSV-1 oral-facial lesions most common HSV usually acquired in childhood fever blisters inside mouth transmitted by infected saliva 90% of adults have Ab’s HSV-2 genital lesions (ulcers or sores) possible complications: meningoencephalitis or infection of the eye (acquired at birth, passing through infected mother’s birth canal) can also be asymptomatic sexually transmitted 25% of 25-45 years old of US population Cross-infection of type 1& 2 viruses may occur from oral-genital contact. For Internal Use Only

Herpes Simplex 1 & 2 (2) Why testing ? Human response to infection: primary infection often subclinal and rarely diagnosed primary infection ?  first IgM followed by IgG virus stays in your system once you’ve been infected reactivation after latency period, may or may not rise lesions Why testing ? Infection contracted during birth is of particular interest  important cause of morbidity and mortality !! Important to determine the immunitary state of women during pregnancy in order to detect serum conversion !! For Internal Use Only

Herpes Simplex 1 & 2 (3) Recommended testing: For Internal Use Only

Helicobacter pylori (1) a bacteria responsible for most ulcers and many cases of chronic gastritis weakens protective coating of stomach & duodendum  digestive juices will iritate sensitive lining of these organs H. pylori infection is linked to stomach cancer having H. pylori in gastrointestinal tract is not always leading to ulcer or gastritis  other factors increase risk For Internal Use Only

Helicobacter pylori (2) Human response to infection: most patients exhibit a strong immune response locally mostly IgA antibodies circulating antibodies are primarily IgG IgGs remain constantly high until infection is eliminated (antibiotics) Treatment of H. pylori: concentration of Ab’s does not correlate with disease severity but succesful treatment can be monitored by decrease of Ab’s Efficacy of treatment  decrease in IgG level over time No treatment: Spontaneous clearing of H. pylori by IgA & IgG is rare  elevated IgA & IgG levels, indicates current infection For Internal Use Only