Disorders of the Immune Response, Including HIV/AIDS

Flashcards about Disorders of the Immune Response, Including HIV/AIDS

Classification of Immunodeficiency States

Primary (congenital or inherited) and Secondary (acquired later in life)

Results of Alterations of the Immune System

Immunodeficiency states, Allergic or hypersensitivity reactions, Transplantation rejection, and Autoimmune disorders

Four Major Categories of Immune Mechanisms

Humoral or antibody-mediated immunity (B lymphocytes), Cell-mediated immunity (T lymphocytes), The complement system, and Phagocytosis (neutrophils and macrophages)

Humoral Immunodeficiencies

B-cell function and immunoglobulin or antibody production are involved; Defects in humoral immunity increase the risk of recurrent pyrogenic infections; Usually is not as important in defending against intracellular bacteria (mycobacteria), fungi, and protozoa; Viruses are usually handled normally, except for the enteroviruses that cause gastrointestinal infections.

Primary Humoral Immunodeficiency Disorders

Genetic disorders of the B lymphocytes; Approximately 70% of primary immunodeficiencies; Immunoglobulin production depends on the differentiation of stem cells to mature B lymphocytes and the generation of immunoglobulin-producing plasma cells; Can interrupt the production of one or all of the immunoglobulins

Immunoglobulin G (IgG)

75% of all antibodies in the human body

Immunoglobulin A (IgA)

Primarily found in mucosal tissues, such as those in the mouth, vagina, and intestines, as well as in saliva, tears, and breast milk; 15% of all antibodies in the human body

Immunoglobulin M (IgM)

One of the first antibodies recruited by the immune system to fight infection; Helps B cells remember a pathogen after it has been destroyed

Immunoglobulin E (IgE)

Responsible for the allergic response that is mostly found in the lungs, skin, and mucosal membranes

Immunoglobulin D (IgD)

Important in the early stages of the immune response; Does not actively circulate but instead binds to B cells to instigate the immune response.

Primary Humoral Immunodeficiency Disorders Transient Hypogammaglobinemia, Selective IgA, Bruton’s Disease

Failure of pre B-cells; Occurs in a baby who has inherited a gene that is linked to the x chromosome that prevents the B cells from maturing, produce no Abs, no IgG; The only Ab they cannot produce IgA, found in tears, saliva, etc., therefore these are the areas likely to get infections

DiGeorge disease

Lack of development of the thymus T-cells can’t mature

Severe combined immune deficiency syndrome (SCIDS)

Problem of stem cell development; Can’t produce either B or T cells

Disorders of the Complement System

Most inherited as autosomal recessive traits and can involve one or more complement components; Can occur in persons with functionally normal complement systems because of rapid activation and turnover or reduced synthesis of complement components; Hereditary angioneurotic edema and loss of regulation

The Phagocytic System Action

Migrate to the site of infection, Aggregate around the affected tissue, Envelope the invading microorganisms, Generate microbicidal substances to kill the ingested pathogens

Dysfunction of the Phagocytic System

A defect in phagocytic functions or a reduction in the absolute number of available cells disrupts the system. Susceptible to Candida species, Filamentous fungi, Chronic granulomatous disease (CGD)

Adaptive Immunity

Development of response to the antigen, Specific humoral and cellular recognition, Memory cells

IgA

found in saliva and tears, vaginal secretions, bronchial, GI, prostatic; primarily found in secretions

IgD

primary function unknown

IgG

the most abundant; present in all body fluids; the only Ab that crosses the human placenta

IgE

involved in inflammation and allergic responses; involved in combating parasites

IgM

the first antibody to be produced by the developing fetus

Hypersensitivity Disorders

Excessive or inappropriate activation of the immune system

Atopic Disorders

Heredity predisposition and production of a local reaction to IgE antibodies produced in response to common environmental agents Urticaria (hives), allergic rhinitis (hay fever), atopic dermatitis, food allergies, some forms of asthma

Nonatopic Disorders

Lack the genetic component and organ specificity of the atopic disorders

Primary or Initial-phase Response for Type I Hypersensitivity Reactions

Vasodilation, Vascular leakage, Smooth muscle contraction

Secondary or Late-phase Response for Type I Hypersensitivity Reactions

More intense infiltration of tissues with eosinophils and other acute and chronic inflammatory cells; Tissue destruction in the form of epithelial cell damage

Type II (Cytotoxic) Hypersensitivity Reactions

Mediated by IgG or IgM antibodies directed against target antigens on the surface of cells or other tissue components

Type II (Cytotoxic) Hypersensitivity Reactions Examples

Mismatched blood transfusion reactions, Hemolytic disease of the newborn, Certain drug reactions

Type III, Immune Complex Allergic Disorders

Mediated by the formation of insoluble antigen–antibody complexes that activate the complement pathway

Systemic and Localized immune complex reactions

Serum sickness and Arthus reaction

Type IV Hypersensitivity Reactions

The principal mechanism of response to a variety of microorganisms, including intracellular pathogens and extracellular agents; Can lead to cell death and tissue injury in response to chemical antigens or self-antigens

Type IV Hypersensitivity Reactions Basic Types

Direct cell-mediated cytotoxicity (Hepatitis), Delayed-type hypersensitivity (Allergic contact dermatitis), Hypersensitivity pneumonitis

Routes of Exposure to Latex

Cutaneous, Mucous membrane, Inhalation, Internal tissue, Intravascular routes

Major Histocompatibility Complex

Set of molecules displayed on cell surfaces, Lymphocyte recognition, Antigen presentation, Controls the immune response through recognition of self and nonself

Allogeneic (allograft)

The donor and recipient are related or unrelated but share similar HLA types

Syngeneic

The donor and recipient are identical twins

Autologous

The donor and recipient are the same person

HVGD

Host vs graft disease referred to as transplant rejection

GVHD

Graft vs host disease; the transplant rejects the person

Central tolerance

The elimination of self-reactive T cells and B cells in the central lymphoid organs (i.e., the thymus for T cells and the bone marrow for B cells)

Peripheral tolerance

Derives from the deletion or inactivation of autoreactive T cells or B cells that escaped elimination in the central lymphoid organs

Hyperacute Reaction

Occurs almost immediately after transplantation; Produced by existing recipient antibodies to graft antigens initiating a type III, Arthus-type hypersensitivity reaction

Acute Rejection

Occurs within first few months after transplantation with signs of organ failure; may occur months or years after immunosuppression has been terminated; T lymphocytes respond to antigens in the graft tissue

Chronic Host-versus-Graft Rejection

Occurs over a prolonged period; Manifests with dense intimal fibrosis of blood vessels of the transplanted organ; The actual mechanism is unclear but may include release of cytokines that stimulate fibrosis

Basic Requirements Necessary for GVHD

The transplant must have a functional cellular immune component; The recipient tissue must bear antigens foreign to the donor tissue; The recipient immunity must be compromised to the point that it cannot destroy the transplanted cells

Autoimmune Diseases

Systemic lupus erythematosus (SLE), Autoimmune hemolytic anemia (AIHA), Pemphigus vulgaris, Hashimoto thyroiditis

Mechanisms of Autoimmune Disease

Heredity and gender, Failure of self-tolerance, Disorders in MHC–antigen complex/receptor interactions, Molecular mimicry, Superantigens

Criteria for Determining an Autoimmune Disorder

Evidence of an autoimmune reaction, Determination that the immunologic findings are not secondary to another condition, The lack of other identified causes for the disorder

Transmission of HIV Infection

Sexual contact, Blood-to-blood contact, and Perinatally.

Phases of HIV Infection

Primary infection phase, Chronic asymptomatic or latency phase, and Overt AIDS phase

Clinical Course of HIV

Respiratory Manifestations, Gastrointestinal Manifestations, ADS dementia, LYMPHOPROLIFERATIVE DISEASE, CNS lymphoma, Persistent generalized lymphadenopathy, B-cell lymphoma, AIDS nephropathy

Treatment for HIV

Reverse transcriptase inhibitors, Protease inhibitors, Fusion inhibitors

What is Immunodeficiency?

A condition characterized by a deficiency in one or more components of the immune system, leading to increased susceptibility to infections and other health problems.

What is Autoimmunity?

The immune system mistakenly attacks the body's own tissues and organs, leading to chronic inflammation and damage.

What is Hypersensitivity?

A exaggerated or inappropriate immune response to a harmless substance, such as pollen or food, leading to inflammation and tissue damage.

What is Humoral immunity?

Mediated by B lymphocytes and involves the production of antibodies that recognize and neutralize foreign antigens.

What is Cell-mediated immunity?

Mediated by T lymphocytes and involves the direct killing of infected cells or the release of cytokines that activate other immune cells.

What is the complement system?

A group of proteins that enhance the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism, promote inflammation, and attack the pathogen's plasma membrane.

What is Phagocytosis?

The process by which phagocytes engulf and destroy foreign particles, such as bacteria and viruses.

Where is IgA primarily found and what is its function?

IgA is primarily found in mucosal tissues, such as those in the mouth, vagina, and intestines, as well as in saliva, tears, and breast milk, and serves as a first line of defense against pathogens at mucosal surfaces.

What is IgG and what is its function?

IgG is the most abundant antibody in the body and is present in all body fluids, providing long-term immunity against a wide range of pathogens. It is also the only antibody that crosses the human placenta, providing passive immunity to the fetus.

What is IgE and what is it involved with?

IgE is involved in inflammation and allergic responses, and is also involved in combating parasites.

What is IgM and what is

IgM is one of the first antibodies recruited by the immune system to fight infection. It is also the first antibody to be produced by the developing fetus.