Immunology and Serology [Midterms]

✦ Cytokines, Complement System, Hypersensitivity, Autoimmunity

Immune Response

Reaction to antigen entry in the host body.

Antibody

Proteins produced to neutralize antigens.

Cytokine Production

Signaling molecules released by immune cells.

LAG Phase

Initial phase with no measurable immune response.

LOG Phase

Slight increase in immune response observed.

Exponential Phase

Rapid increase in antibody concentration occurs.

Steady State

Balance between antibody production and degradation.

Decline Phase

Immune system activity begins to decrease.

Primary Humoral Immune Response

First exposure leading to antibody formation.

Log Phase Duration

1 to 2 weeks for measurable adaptive response.

Humoral Immunity

Involves B cell activation and antibody production.

Antigen Elimination

Removal of antigens via phagocytosis.

Latent Period

5 to 15 days before antibodies appear.

Secondary Humoral Immune Response

Faster response upon re-exposure to antigen.

Memory Response

Quick antibody production due to memory cells.

IgM Antibody

First antibody produced during initial exposure.

IgG Antibody

Produced during subsequent exposure to the same antigen.

Plasma Cells

B cells transformed to produce antibodies.

Memory Cells

Cells that remember previous antigen exposure.

Adaptive Immunity

Specific immune response involving memory and recognition.

Phagocytosis

Process of engulfing and destroying pathogens.

Antigen Recognition

Initial identification of antigens by immune cells.

Antibody Production

Formation of antibodies in response to antigens.

Immunoglobulin

Proteins that function as antibodies in immune response.

Antibody Stages

Four stages: log, exponential, steady, decline.

Cell-Mediated Immune Response

Involves T cells responding to antigen recognition.

CD4 Cells

Helper T cells that assist in immune response.

CD8 Cells

Cytotoxic T cells that kill infected cells.

Antibody Titer

Amount of antibody produced in response to antigen.

Primary Response

Initial immune response with low antibody titer.

Secondary Response

Subsequent immune response with higher antibody titer.

Intracellular Antigens

Antigens primarily found within cells.

MHC Antigens

Molecules necessary for T-cell recognition of antigens.

Cytokines

Chemical messengers influencing immune cell activities.

Autocrine Action

Cytokines act on the same cell that released them.

Paracrine Action

Cytokines act on nearby cells instead of self.

Pleiotropy

Cytokines affecting multiple cell types.

Redundancy

Multiple cytokines having similar effects on the body.

Cytokine Types

Monokines from macrophages; lymphokines from lymphocytes.

Interferons

Cytokines with antiviral properties; Types 1 and 2.

Class I MHC

Required for CD8 T-cell activation and recognition.

Class II MHC

Required for CD4 T-cell activation and recognition.

Cytokine Hyperactivation

Increased cytokines leading to immune cell overactivity.

Cytokine Functions

Regulate both innate and adaptive immune responses.

Antigen Phagocytosis

Process where macrophages engulf and process antigens.

Cytokine Actions

T cells produce cytokines for direct or indirect killing.

Cytokine Storm

Life-threatening systemic inflammatory syndrome with elevated cytokines.

C-reactive Protein (CRP)

Marker universally elevated in cytokine storm severity.

Hypertriglyceridemia

Elevated triglycerides in blood, common in cytokine storm.

Leukocytosis

Increased white blood cells in response to infection.

Leukopenia

Decreased white blood cells, indicating immune suppression.

Anemia

Deficiency of red blood cells or hemoglobin.

Thrombocytopenia

Low platelet count, increasing bleeding risk.

Elevated Ferritin

High ferritin indicates inflammation or iron overload.

Elevated D-dimer

Marker for blood clot formation and breakdown.

COVID-19 and Cytokine Storm

COVID-19 can trigger severe cytokine storms.

Complement System

Plasma proteins enhancing immune defense reactions.

Plasma Proteins

More than 50 proteins involved in immune response.

C3 Protein

Key mediator in all complement activation pathways.

C1 Protein

First complement protein activated in classical pathway.

C4 Protein

Activated by C1, forms C4a and C4b products.

Opsonization

Enhancement of phagocytosis by marking pathogens.

Lysis of Cells

Destruction of cells, including bacteria and tumors.

Inflammatory Mediators

Substances generated to activate inflammatory responses.

Classical Pathway

Complement activation initiated by antigen-antibody complex.

Alternative Pathway

Antibody-independent activation by foreign cell surfaces.

Lectin Pathway

Initiated by host proteins binding to microbial sugars.

Sequential Activation

Stepwise activation of complement proteins for immune response.

Immune Complex Clearance

Removal of antigen-antibody complexes from circulation.

Pollen

Fine powder from plants, often allergenic.

Hypersensitivity

Exaggerated immune response to antigens.

Asthma Types

Respiratory and skin-related allergic reactions.

Anaphylactic Reaction

Severe allergic response, potentially life-threatening.

Allergy

Altered reactivity to antigens or haptens.

Antigen-Presenting Cells

Cells that process and present antigens.

B Cells

Lymphocytes that produce antibodies upon activation.

Atopic Individual

Person sensitive to various allergens.

Homocytotropic Antibody

Antibodies like IgE that trigger allergic reactions.

Desensitization

Treatment to reduce reactivity to allergens.

Immediate Hypersensitivity

Rapid allergic reaction occurring within minutes.

Delayed-Type Hypersensitivity

Allergic reaction occurring hours to days later.

Type 1 Hypersensitivity

Immediate allergic response mediated by antibodies.

Type 4 Hypersensitivity

Delayed response mediated by T cells.

Type 2 Hypersensitivity

Antibody-mediated tissue damage.

Type 3 Hypersensitivity

Immune-complex mediated tissue damage.

IgE

Antibody associated with allergic reactions.

Mast Cells

Cells that release histamine during allergic reactions.

Basophils

White blood cells involved in allergic responses.

Histamine

Chemical released during allergic reactions causing inflammation.

Prostaglandin

Lipid compounds involved in inflammation and allergic responses.

Allergic Mediators

Substances released during allergic reactions causing symptoms.

Inflammation

Body's response to injury or infection, often allergic.

Type IV Hypersensitivity

Delayed-type hypersensitivity mediated by T cells.

Delayed-type Hypersensitivity

Hypersensitivity that develops days after antigen exposure.

Cytokines

Proteins released by T cells causing inflammation.

Antigen-presenting cells

Cells that present antigens to T cells.

HLA molecules

Human leukocyte antigen involved in T cell activation.

Inflammatory conditions

Conditions caused by cytokine release.

Tuberculin test

Test for TB inflammation after 3 days.

Type I Diabetes Mellitus

Autoimmune condition damaging insulin-producing cells.