Immunology and Serology - 05 Disadvantages of Immune System

• IMMUNOLOGY AND SEROLOFY DISADVANTAGES OF THE IMMUNE SYSTEM OUTLINE • • Hypersensitivity o Four Types of Hypersensitivity Autoimmunity o Clinical Significance o Laboratory Diagnosis • HYPERSENSITIVITY • • • • Hypersensitivity results when foreign antigens induce cellular or antibody immune responses, leading to host tissue damage Aka allergic reactions Can cause detrimental effect on the host Allergy - altered state of reactivity to antigen/haptene o Involves hyper & hyposensitivity o Hypo-sensitization - can be used for treatment o Hypersensitivity - cause detrimental effect FOUR TYPES OF HYPERSENSITIVITY • • • Autoimmunity occurs when immune response is directed against self-antigens, resulting in host tissue damage. Classification of hypersensitivity o Classification according to time/temporal relation ▪ Immediate type ▪ Delated type o Classification according to tissue injury ▪ Type I ▪ Type II ▪ Type III ▪ Type IV o Gel and Coomb’s Classification Immediate (Type I) hypersensitivity reactions o Commonly called allergies/atopy, occur within minutes after exposure to antigen o Mechanism: degranulation of mast cells (tissue) and basophils (blood) w/ release of histamine, prostaglandin o Utilizes IgE (related to allergy) ▪ IgE - cytotropic antibody ▪ Cytotropic - abs with ability to bind to the surfaces of mast cells and basophils o Atopic - highly sensitive to certain antigens ▪ Produces IgE ▪ Upon subsequent exposure /shocking dosage to inducer/offender antigens, B cell will produce IgE which will bind to mast cells & basophil inducing release of histamine and prostaglandin which manifests as allergic reaction o Anaphylaxis/anaphylatoxin mechanism - immediate release of histamine and other allergic mediators o Can cause difficulty in breathing due to effect in respiratory passages (anaphylactic shock) o Ex. hay fever (allergic rhinitis), asthma, eczema, atopic dermatitis, anaphylaxis to drugs, food allergies, allergy to animals and animal products ▪ Inhalant allergy/atopy (dusts, animal danders) ▪ Ingestant allergy ▪ Injectant allergy (drug allergy) ▪ Miscellaneous allergy (weather-induced, etc.) o Neutralized by the use of anti-histamine • • Type IV hypersensitivity, or delayed-type hypersensitivity (DTH) o Cell-mediated hypersensitivity o Characterized by tissue damage due to inflammatory responses o Mechanism: release of cytokines by sensitized T cells o Occurs within 24-28 hours o Ex. leprosy, tuberculin, Hashimoto’s, poison ivy, type 1 DM, acute and chronic graft rejection, contact dermatitis (exposure to chemicals) o Neutralized by using of muscle relaxants (steroids, etc) Mediators of immediate hypersensitivity reactions o histamine o chemokines o granule-associated enzymes o prostaglandins o leukotrienes C4, D4, E4 o leukotrienes B4 Antibody-dependent, complement-mediated types o Type II (antibody-mediated) ▪ Based on cytotoxic reactions ▪ Mechanism: cytolysis due to ab and Complement ▪ Ex. drug-induced hemolytic anemia, HDN, hyperacute graft rejection, Goodpasture syndrome, rheumatic fever, myasthenia gravis, Grave’s, type 2 DM o Type III (immune-complex-mediated) ▪ Mechanism – deposition of antigen-antibody complexes • Deposited in the basement membrane of tissues (kidneys) • May lead to tissue injury in the presence of complement ▪ Ex. SLE, RA, poststreptococcal glomerulonephritis, vasculitis, serum sickness • Hypersensitivity Class Description Immune Mechanism Type I Immediate IgE sensitization of mast cells Time of Example Latency Minutes Reaction to bee venom (sting) Type II Cytotoxic* IgG interaction w/ Hours Drug reaction cell surface (penicillin) antigen Type III Immune IgG interaction w/ Hours Systemic lupus complex soluble or erythematosus circulating antigen (SLE) Type IV Delayed TH1 inflammatory Days Poison ivy type cells (24-48h) Tuberculin test *Autoimmune diseases may be caused by Type II, Type III, or Type IV reactions Antibody Comple- Effector Examples (Clin. ment Cells Significance) Type I IgE No Basophil, Hay fever, Atopic Anaphylactic Mast cell dermatitis, Insect venom, Food Type II IgM, IgG Yes PMN, Hemolytic anemia, Cytotoxic NK, transfusion rxns, Microorg. Goodpasture Type III IgM, IgG Yes PMN, SLE, RA, Arthus Immune Microorg rxn, Serum Complex sickness Type IV None No T cell TB, Leprosy, Delayed-Type Tuberculin, Hypersensitivity Contact Dermatitis, Graft Rejection • CLINICAL SIGNIFICANCE Type SYSTEMIC LUPUS ERYTHEMATOSUS (SLE) • A disease that can damage the joints, skin, kidneys, heart, lungs, and other parts of the body. Also called SLE or lupus. • Symptoms: o Fever o Weight loss o Hair loss o Mouth sores o Fatigue o "Butterfly" rash across the nose and cheeks o Rashes on other parts of the body o Painful or swollen joints and muscle pain o Sensitivity to the sun o Chest pain o Headache, dizziness, seizure, memory problems, or change in behavior Here is the famous "LE cell" test which has value only in demonstrating how the concept of autoantibodies work. The pink blobs are denatured nuclei. Here are two, with one seen being phagocytozed in the center by a PMN. This test is not nearly as sensitive as the ANA which has supplanted the LE cell test. AUTOIMMUNITY • • • • • Autoimmunity – expression of the immune response that occurs when the body’s self-tolerance system fails. The body’s immune cells are no longer able to recognize “self” – those antigens are self-molecules phenomenon referred to as “self-tolerance”. This can result in unrelated diseases known as autoimmune diseases. Autoimmune response is strongly influenced by MHC antigens. Ex. Goodpasture’s syndrome, myasthenia gravis, Type I diabetes, Grave’s disease Features of autoimmunity o Predominant in females, but males are not exempted o Inheritable & chance of genetic predisposition o Presence of hypergammaglobulinemia (excess abs) o Presence of autoantibodies o Presence of hypocomplementemia (complement deficiency) Autoimmune diseases may be organ-specific or systemic: o Organ specific ▪ Hematologic disorders: • Paroxysmal cold hemoglobinuria • Warm autoimmune haemolytic anemia (AIHAs) • Immune thrombocytopenic purpura (ITP) ▪ Endocrine disorders • Grave’s disease • Hashimoto’s thyroiditis • Insulin-dependent diabetes mellitus ▪ Neuromuscular disorders • Myasthenia gravis • Multiple sclerosis ▪ Renal disorders • Goodpasture’s syndrome • Tubulo-interstitial nephritis ▪ Gastrointestinal disorders • Pernicious anemia • Primary biliary cirrhosis o Systemic diseases, Multi-organ or Multi-tissue involvement ▪ Rheumatoid Arthritis ▪ Polymyositis ▪ SLE • • SCLERODERMA • • • A disease causing abnormal growth of connective tissue in the skin and blood vessels. Symptoms o Fingers and toes that turn white, red, or blue in response to heat and cold o Pain, stiffness, and swelling of fingers and joints o Thickening of the skin o Skin that looks shiny on the hands and forearm o Tight and mask-like facial skin o Sores on the fingers or toes o Trouble swallowing o Weight loss o Diarrhea or constipation o Shortness of breath ANKYLOSING SPONDYLITIS INFECTIOUS MONONUCLEOSIS • • • • is a form of chronic inflammation of the spine and the sacroiliac joints SJOGREN’S DISEASE • • A disease in which the immune system targets the glands that make moisture, such as tears and saliva. Symptoms o Dry eyes or eyes that itch o Dryness of the mouth, which can cause sores o Trouble swallowing o Loss of sense of taste o Severe dental cavities o Hoarse voice o Fatigue o Joint swelling or pain o Swollen glands o Cloudy eyes • PERNICIOUS ANEMIA • • GRAVE’S DISEASE • • A disease that causes the thyroid to make too much thyroid hormone Symptoms o Insomnia o Irritability o Weight loss o Heat sensitivity o Sweating o Fine brittle hair o Muscle weakness o Light menstrual periods o Bulging eyes o Shaky hands o Sometimes there are no symptoms • A disease in which the immune system attacks the lining of the joints throughout the body Symptoms o Painful, stiff, swollen, and deformed joints o Fatigue o Fever o Weight loss o Eye inflammation o Lung disease o Lumps of tissue under the skin, often the elbows o Anemia Condition that manifests in individuals (small percent) who have severe chronic gastritis. Symptoms: Unnaturally pale, fatigue, breathlessness, lethargy and depression, tingling in the hands and feet, color blindness involving blue and green and confusion. Patients with pernicious anemia have an increased incidence of gastric cancer. • MYASTHENIA GRAVIS • • RHEUMATOID ARTHRITIS • causative agent is Epstein Barr virus Presence of “Downey cells” (enlarged lymphocytes) EBV infection is most common during adolescence and early adulthood Symptoms: fever, fatigue, sore throat, swollen lymph glands A disease in which the immune system attacks the nerves and muscles throughout the body Symptoms o Double vision, trouble keeping a steady gaze and drooping eyelids o Trouble swallowing, with frequent gagging or choking o Weakness or paralysis o Muscles that work better after rest o Drooping head o Trouble climbing stairs or lifting things o Trouble talking LABORATORY DIAGNOSIS SYSTEMIC LUPUS ERYTHEMATOSUS • Indirect Fluorescent Antibody Test for Detection of Antinuclear Antigen (ANA) o Aka Fluorescent Antinuclear Antigen (FANA) Test o Principle: Indirect Immunofluorescence o Fluorescent Staining Patterns ▪ Homogenous (solid, diffuse) • typically seen in RA, drug-induced SLE, Sjogren’s syndrome & MCTD ▪ Peripheral/Rim (Ring, membranous) • associated with SLE in the active stage and Sjogren disease RHEUMATOID ARTHRITIS • • • ▪ Speckled (mottled, “pepper-dots”) Rapid agglutination test o Sheep rbcs – latex coated with denatured gamma globulin o False (+) – sle, sjogren’s, syphilis, hepatitis Bentonite flocculation Anti-CCP (cyclic citrullinated peptide) o Titer of 80 or greater – generally considered a positive reaction o Titer of 20 to 40 – considered a weakly positive reaction o No agglutination at 1:20, specimen should be considered negative for rf even if subsequent dilution shows agglutination TRANSPLANTATION AND TUMOR IMMUNOLOGY TRANSPLANTATION ▪ Nucleolar • associated with SCLERODERMA, Sjogren’s, SLE and Raynaud’s phenomenon • • • • • • • ▪ o Anti-Centromere Antibody (ACA) • CREST variant of scleroderma Aka grafting Process of transferring one tissue or organ from one individual to another Transfer of tissue or organ from one individual to another whereas transfusion refers to transfer of blood from one individual to another Antibodies are responsible for transfusion reactions Rejection of transplanted tissue is mediated predominantly by T cells Transfusion - transfer of blood and other blood products Transplants are usually expected as successful o Used as treatment Antinuclear Antibody (ANA) Visible Method ▪ Principle: Indirect Immunoenzyme Method INFECTIOUS MONONUCLEOSIS • Tests For Heterophile Antibodies o Paul-Bunnel Test ▪ Hemeagglutination ▪ Positive result – hemeagglutination o Davidsohn Differential Test ▪ Patient serum is mixed with beef rbcs and guinea pig kidney cells o Monospot ▪ Indicators: horse cells ▪ Positive result: if the horse rbcs are agglutinated by the patient serum absorbed with guinea pig kidney and not agglutinated by the patient serum absorbed with beef rbcs o Rapid Differential Slide Test using papain-treated sheep rbcs (hemeagglutination) • TYPES OF TRANSPLANTATION • • • • Autologous graft (autograft): within an individual, auto transplantation, usually successful due to almost similar genetic makeup between donor and recipient Syngeneic graft (syngraft, isograft): identical twins, isotransplantation, usually successful due to almost similar genetic make up between donor and recipient Allogeneic graft (allograft, homograft): non-identical, allotransplantation o Always unsuccessful due to varying genetic makeup between donor & recipient o Immunosuppressive measures are done to increase success and survival Xenogeneic graft (heterologous graft, heterograft): between species, xenotransplantation AUTOGRAFT • • • • A graft or transplant from one area to another on the same individual Graft is recognized as autologous (self) same person e.g. transplanting blood vessel from the leg to the heart during cardiac bypass surgery No immune response is induced against it ISOGRAFT OR SYNGRAFT • • • Graft or transplantation of cells, tissue or organ from one person to another who is syngeneic (genetically identical) to the donor The recipient who is genetically identical to the donor recognizes the donor’s tissue as self Does not mount an immune response against it ALLOGRAFT • • Graft or transplant from one individual to another with a different genetic make-up, within the same species, e.g. kidney transplant from one person to any other (except an identical twin) Graft is recognized by recipient as foreign and is immunologically rejected XENOGRAFT • • • Graft between a donor and a recipient from different species Transplant is recognized as foreign and immune response mounted against it will destroy or reject graft E.g. transplanting a heart from a baboon to a human LABORATORY TESTS FOR TRANSPLANTATION • • • • • • • Rejection occurs due to incompatibilities as transplanted organ/tissue is acknowledged as foreign by the host’s body Hyperacute rejection o Minutes to hours o Preexisting antibodies to donor HLA antigens o Complement activation, macrophages o Occurs within a few minutes to a few hours of transplant o These antibodies activate complement system followed by platelet activation and deposition causing swelling and interstitial hemorrhage in the transplanted tissue. o Recipient may have fever, leukocytosis, and produce little or no urine o At present there is no therapy for successful prevention or termination of hyperacute rejection Accelerated rejection Acute rejection o Around 10 days to 30 days o Cellular mechanism (CD4, CD8, NK, macrophages) o Seen in recipient who has not previously been sensitized to transplant o Common type of rejection experienced by individuals for whom transplanted tissue is a mismatch o Reaction may begin a few days after transplantation of a kidney, with a complete loss of kidney function within 10-14 days o Accompanied by a rapid decrease in renal function ABO Blood Typing Tissue typing (HLA Matching) o Lymphocytotoxicity test o Mixed leukocyte reaction Screening for Presence of Preformed Antibodies to allogeneic HLA Crossmatching GRAFT-VS-HOST (GVH) DISEASE • • • • CLINICAL PHASES OF REJECTION • Chronic rejection o Months to years o Mixed humoral and cellular mechanism o Chronic rejection is still hard to manage o Caused by both antibody and cell mediated immunity occurs in allograft transplantation months after transplanted tissue has assumed its normal function o In kidney transplantation, is characterized by slow, progressive renal failure o Bone marrow and skin grafts are very sensitive to rejection compared to heart, kidney and liver Can occur in the special case in which immunocompetent tissue (fresh whole blood, thymus, or bone marrow) is transplanted into an immunocompromised host T cells from the transplant recognize the host MHC molecules as non-self and attack the host This is a type IV hypersensitivity reaction; antibody plays no role at all. Situations leading for GVH o Allograft in a recipient in whom specific immunological tolerance has been induced o Present with clinically o Retardation of growth o Diarrhea, Hepatosplenomegaly o Lymphoid atrophy o Anemia o Terminating fatally o Syndrome is called Runt disease CLASSIFICATION OF TRANSPLANTS • • • Based on nature of organs - kidney, liver, heart, bone marrow, skin On basis of anatomical site - orthotropic, heterotypic o Orthotropic - skin graft o Heterotypic graft - on abnormal site (eg. Thyroid gland in subcutaneous region) TUMOR IMMUNOLOGY • • • Tumor marker o Substance produced by a tumor or by the host in response to a tumor which is used to differentiate a tumor from normal tissue or to detect the presence of a timor based on measurements in blood or scretions o Found in cells, tissues, or body fluids Ideal tumor marker should be o Highly specific o Highly sensitive o Specific to a particular organ o Correlate with the prognosis o Have a reliable prediction value But ideal tumor marker does not exist CANCER • • • • • • • Aka neoplasm Multigene disease which arises as a result of mutational and epigenetic changes coupled with activation of complex signaling networks Malignant - invasive type; can affect other organs & tissues It involves alteration of three main classes of genes o Protooncogenes - regulatory genes that promote cell division ▪ Normally promote cell growth; mutations change them into oncogenes whose products are excessively active in growth promotion. ▪ Oncogenic mutations usually result in either increased gene expression or production of a hyperactive gene product o Tumor suppressor genes - genes that inhibit the growth of tumors. ▪ normally restrain growth, so mutations that inactivate them allow inappropriate cell division o DNA repair genes - involved in maintaining the genome’s integrity This contributes to development of cancer genotype and phenotype. These genetic alterations include geen rearrangements, point mutations, and gene amplifications leading to disturbances in molecular pathways regulating cell growth, survival, and metastasis When these changes manifest in majority of patients with specific type of tumor, this can be used as tumor markers (biomarkers) Can also be used for detection and developing targeted therapies besides predicting responses to treatment TUMOR MARKERS ENZYMES AS TUMOR MARKERS • • • • • HORMONES AS TUMOR MARKERS • • • • • • • 1846 - Bence-Jones protein 1940 - acid phosphatase 1960 - immunoassay 1963 - Alpha-fetoprotein 1965 - Carcinoembryonic antigen 1970 - Oncogenes 1975 - Monoclonal antibodies 1980 - CA 125, PSA, Carbohydrate antigens, Tumor Suppressor Genes 2001 - Microarrays, Mass Spectrometry, Neural Networks, Multiparametric Analysis Adrenocorticotropic hormone (ACTH) - Cushing’s syndrome, lung cancer Antidiuretic hormone (ADH) - lung, adrenal cortex, pancreatic Bombesin - lung Calcitonin - medullary Ca thyroid Vasoactive intestinal peptide - pheochromocytoma, neuroblastoma Human chorionic gonadotropin - choriocarcinoma. Embryonal PROSTATE SPECIFIC ANTIGEN (PSA) • • • • • Only marker used to screen for a common type of cancerprostate cancer PSA is a single chain glycoprotein specific for prostatic tissue Gene encoding PSA has been sequenced and located on chromosome 19 PSA is a serine protease of the kallikrein family (KLK3) Sandwich immunoassays are used to measure PSA ONCOFETAL ANTIGENS • • • • • • • HISTORICAL BACKGROUND OF TUMOR IMMUNOLOGY • • • • • • • • Alcohol dehydrogenase & aldolase - liver cancer Alkaline phosphatase - bone, liver, leukemia Prostatic acid phosphatase - prostate Neuron specific enolase - small cell lung cancer, neuroblastoma, melanoma Lactate dehydrogenase - lymphoma, leukemia Aka carcinoembryonic antigens Alpha fetoprotein (AFP) - hepatocellular, germ cell tumor Carcinofetal Ferritin - liver Carcinoembryonic Antigen (CEA) - colorectal, gastrointestinal, lung, breast, pancreatic Squamous cell antigen - cervical, lung, skin, head & neck Tennessee antigen - colon, gastrointestinal, bladder Cytokeratins o Tissue polypeptide antigen - breast, colorectal, ovarian, bladder o Tissue polypeptide specific antigen o Cytokeratin 19 fragments (CTFRA-21-1) - a prognosic marker for non-small cell lung cancer PROTEINS AS TUMOR MARKERS • • • • • • • Beta 2 macroglobulin - multiple myeloma, CML, Waldenstrom’s macroglobulinemia C-peptide - insulinoma Ferritin - liver, lung breast, leukemia Immunoglobulins - multiple myeloma, lymphomas Melanoma associated antigen - melanoma Des-gamma-carboxy prothrombin - hepatocellular Soluble mesothelin related peptides - mesothelioma, ovarian CARBOHYDRATES OR MUCIN AS TUMOR MARKERS • • • • • • CA-125 - ovarian, endometrial CA-15-2 - breast, ovarian CA-549 - breast, ovarian CA-27.29 - breast Mucin-like Carcinoma associated antigen (MCA) breast, ovarian DU-PAN-2 - pancreatic BLOOD GROUP ANTIGEN RELATED MARKERS • • • • • CA 72-4 - newer test for ovarian, pancreatic & stomach cancer; studies of this marker are still in progress CA 19-9 - pancreatic, gastrointestinal, hepatic, best for pancreatic cancer CA 19-5 - pancreatic, gastrointestinal, ovarian CA 50 - pancreatic, gastrointestinal, colon CA 242 - pancreatic, gastrointestinal ONCOGENES • • • • Oncogenes are derived from proto-oncogenes that may be activated by dominant mutations, insertions, deletions, translocations, or inversions Most oncogenes code for proteins needed for proliferation and their activation leads to cell division Most oncogenes are associated with hematologic malignancies such as leukemia and to a lesser extent solid tumors More than 40 proto-oncogenes are recognized but only few are useful as tumor markers BREAST CANCER ONCOGENES • • • Her-2/neu (ERBB2) o This gene codes for EGF family of tyrosine kinase receptors which are involved in cell proliferation, differentiation, and survival o Amplification of this gene is found in breast, ovarian, and gastrointestinal tumors o Herceptin treatment is administered only to those breast cancer patients who have Her-2/neu amplification o Immunohistochemistry is used to detect increased expression of this protein o FISH is used for detection of HER-2/neu gene amplification Oncogene c-erbB-2 gene o Over expressed in 30% of breast cancers, correlation between c-erbB-2 gene positivity, positive axillary node status, reduced time to relapse and reduced overall survival BRCA1 gene on chromosome 17q o Familial breast-ovarian cancer syndrome o Breast cancer in early-onset breast cancer families o High risk screening VIRAL BIOMARKERS • Hepatocellular cancer o HBV promotes carcinogenesis through genetic instability generated by its common integration in host DNA o These markers include ▪ Analysis of viral DNA or proteins produced against the viral proteins ▪ HBsAG ▪ HBeSG ▪ Anti-HBV core-antigen ▪ Anti-HBeAG, anti-HbsAG