Immunopathology Flashcards by Maria Ella Recare

primarily serves to defend the animal body against infections.

immune system

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These untoward responses of the
immune system that result to tissue
injuries are called?

immunopathologic reactions

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is the study of diseases caused by or
resulting from immune mechanisms,
and is concerned primarily with
untoward consequences of immune
reactions.

immunopathology

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immune system consists of?

effector cells and substances

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provide protection to an individual
following antigenic challenge

effector cells and substances

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two responses of the immune system:

✓ humoral response
✓ cellular response

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mediated largely by antibodies and other effector substances such as complement

humoral response

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mediated by sensitized lymphocytes and cells of the reticulo-endothelial system

cellular response

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antigens is also known as?

immunogens

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are macromolecules that are either natural or synthetic in origin that are capable of inducing immune response. They are usually microbial or foreign proteins or polysaccharide

antigens

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are simple molecules that bind to performed antibodies or sensitized immune cells and can induce an immune response when coupled to a carrier protein

haptens

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usually, macrophages and
dendritic cells process the antigen
and present the same to B
lymphocytes.

Antigen Presenting Cell (APC)

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are specific clones of white blood cell
lymphocytes produced in the bone
marrow.

B-lymphocytes or B-cells

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undergo a series of transformation into an antibody secreting plasma cell
through the aid of inducer T-
lymphocytes

sensitized B cells

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contain the antigen binding sites, and a fragment labeled

Fab

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that contains receptors for complement and effector cells

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Enzyme studies showed that there are two fragments. What are these two?

Fab and Fc

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Two types of lymphocytes are recognized;

✓ B Lymphocytes
✓ T Lymphocytes

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that largely produce the
antibodies

B lymphocytes

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that mediate cellular reactivity

T lymphocytes

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are
by no means a homogenous
population like the B-cells

T-lymphocytes (T-cells)

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There are two functional classes of T
cells:

✓ helper/inducer T cells
✓ cytotoxic/suppressor T-cells

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Activated T cells secretes what?

interleukin-2
(IL-2 or T cell growth factor) that
stimulates the production of IL-2 receptors and the proliferation of T
cells

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The helper T cells also secretes?

IL-4, IL-5, and IL- 6 (B cell growth
factors) that promote the proliferation and maturationof B cells.

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showed that the two major classes of T cells could be distinguished one from the other

Surface Marker Studies

Helper cells

CD4 positive T cells

cytotoxic/suppressor T cells

CD8 positive cells

are surface glycoproteins that functions as adhesion molecules and as co-receptors for antigen.

CD4 and CD8

The ability of the animal body’s immune system to distinguish _________ from ___________is one of the most fascinating features of the immune system

self from nonself

Studies of the immune reactions towards organ transplantation showed this capability is under fine control in specific locus of the genes called?

the major histocompatibility complex

In humans, this locus is located at chromosome 6 and is called?

human lymphocyte antigen complex (HLA complex)

This chromosome region codes for surface proteins in body cells called?

histocompatibility antigens or transplantation antigens

MHC gene products are classified into three categories. What are these?

✓ Class I Antigen ✓ Class II Antigen ✓ Class III Antigen

are glycoproteins present on all nucleated cells and platelets

Class I Antigen

exist as bimolecular protein complexes restrictedly found in antigen presenting cells (monocytes, macrophages, dendriticcells), B cells, and some activated T cells

Class II Antigens

antigen presenting cells

monocytes, macrophages and dendritic cells

are protein components of the complement system(C2, C4 and Bf) that are coded for within the MHC. These proteins do not function as histocompatibility antigens.

Class III Antigens

it regulates the cell-to cell interaction in the immune responses

MHC

facilitate interactions among lymphocytes and between lymphocytes and macrophages in the process of immune recognition

Class II Antigens

are able to recognize antigens only in the form of antigenic peptide complexed with Class II antigens on the surface of antigen presenting cells

T helper Cells (CD4+)

recognize antigens presented on the surface as antigenic peptide complexed with Class I MHC molecules

cytotoxic T cells

activated antigen presenting cells

macrophages, dendritic cells and Langerhans cells

When an antigen gains entry into the animal body, it is first ingested and processed by activated antigen presenting cells into antigenic fragments that expresses?

epitopes or its antigenic determinants

composed of surface membrane bound monomeric IgM programmed during B cell maturation in the gut associated lymphoid tissues in mammals

B cells receptor for antigens

are antibody-like molecules located on the surface membrane, and is programmed during cellular maturation of the T cells at the thymus

receptor for T cells

it is coded for by DNA rearrangement of coding segments to produce the receptor diversity

B cell receptors

consists of plasma proteins belonging to the beta-globulin fraction of the plasma and is normally synthesized by hepatocytes, macrophages,and gut epithelial cells

complement

It is the main effector pathway of the immune response and has a receptor unit able to recognize antibody molecules

complement

The complement components are labeled

C1, C2, C3, C4, C5, C6, C7, C8 and C9

activated via two pathways:

classical and alternate pathway

is initiated by the binding of antigen antibody complexes to C1 that self-activates and cleaves C4 and C2 into C3convertase

classical pathway

C3 splits into two fragments

C3a and C3b

is released and increases vascular permeability

C3a

forms a complex called C5 convertase that splits C5 into C5a and C5b

C3b

increases vascular permeability and attracts polymorphonuclear and mononuclear leucocytes

C5a

initiates the terminal sequence C5b-C9 forming the membrane attack comple

C5b

that effect irreversible lesions on cell membranes leading to cytolysis

membrane attack complex (mac)

the alternate pathway is initiated by a variety of substances including?

✓ bacterial polysaccharides ✓ zymosan ✓ lgA

is a generic term for polypeptide messenger molecules secreted lymphoid and non-lymphoid cells that mediates and regulates the growth, differentiation, and function of cells involved in immunity, hemopoiesis and inflammation

cytokines

are cytokines secreted by lymphocytes

lymphokines

are cytokines secreted by macrophages and monocytes

monokines

is a cytokine that carries messages between lymphocytes.

interleukin

are chemotactic cytokines produced by macrophages, monocytes and T cells that attract leucocytes to the site of inflammation or infection

chemokines

The paramount function of the immune system is to?

✓ recognize foreign antigens ✓ protect the individual

These responses that result in tissue injury are called

hypersensitivity reactions (allergic or immunopathologic reactions)

the release of these could cause tissue injuries;

✓ vasoactive substances, ✓ phagocytosis or lysis of cells ✓activation of inflammatory and cytolytic components of complement, ✓ and release of proteolytic enzymes, ✓ cytokines ✓ other mediators of inflammation from participating inflammatory cells

is a prominent component of this reaction, and is an important process in host defense against viral and fungal infections, and inspontaneous tumor rejection.

cytotoxicity

Type IV is involved in clinically diverse conditions such as?

✓ allergic contact dermatitis ✓ tuberculin hypersensitivity ✓ organ and tissue transplant rejection ✓ graft-vs-host disease

A more common example of type IV reaction includes?

✓ flea allergy ✓ allergic contact dermatitis in dogs and cats

Untoward immune response towards administration of drugs is called?

adverse drug reaction

The basic mechanisms are those described under hypersensitivity states, and the condition is considered if it meets the followingcriteria:

1. The onset of hypersensitivity state does not occur until sometime after initial exposure to a drug 2. After the reaction has been established, the same may be elicited by minute amount of the drug in question; 3. The same reaction recur upon repeated exposure to the same drug; 4. The reaction does not resemble the known pharmacological action of the drug; 5. The symptoms are suggestive of known forms of hypersensitivity reaction

There are several predisposing factors for the development of ADR, and these include;

✓ host factor ✓ drug factor ✓ route of administration ✓ dose duration of exposure.

in this factor, the genetic composition may determine the difference in drug metabolism that may be related to hypersensitivity to certain metabolites of the drug, the differences in the capacity to respond to an immune challenge, the difference in tissue receptor sites, and the elaboration of mediators of the immune system that causes the variations in the severity of hypersensitivity reactions.

host factor

in this factor, the tendency of a drug to induce immune response that results in a hypersensitivity reaction depends on the capacity of the drug or its metabolites to act as or form a complete antigen or hapten. The route of application of the drug, its dose and duration of therapy may influence ADR. Topical application of drugs has the greatest capacity to induce ADR followed by intravenous, intramuscular and oral route

drug factors

is defined as a failure of the individual to recognize its own tissues thus resulting to immune recognition and consequent immune reactions.

autoimmunity

they shrouded the possibility of the immune system working against self as a cause of disease;

✓ Burnet’s clonal selection hypothesis ✓ Erlich’s “horror autotoxicus” ✓ the introduction of Koch’s postulate on the causation of disease

arises when there is a disordered regulation and interaction of the T cells and the B cells in response to an antigenic challenge or stimulation

autoimmunity

involves a balance between the activity of suppressor T cell clones and inducer T cell clones

central mechanism

the sensitizing antigens

self-antigens

Most self-antigens

autoantigens

There are several reactions involving bypass of T cell specificity in the presence of competent B cell that result to the production of auto antibodies and include the following:

1. Binding of foreign haptens as drugs to host tissues 2. Infections by viruses and bacteria that alter host autoantigens 3. Exposure to altered or cross- reacting antigens 4. Stimulation of competent B cell by bacterial lipopolysaccharide 5. Non-specific stimulation of inducer T cell activity by adjuvant in vaccines 6. Graft-versus-host reaction

Immunopathology Flashcards

(81 cards)