Specific Immune Defenses

Flashcards covering the cellular and humoral components of specific immunity, including T-cell and B-cell functions, antibody classes, and types of immunization.

What are specific immune defenses also known as?

Acquired or adaptive immunity

What are the four core characteristics of specific immunity?

Specificity, Diversity, Self-tolerance, and Memory

How is the "Specificity" trait of the immune system defined?

The ability to recognize and eliminate particular microorganisms.

Which trait allow the immune system to respond to millions of different invaders?

Diversity

What is "Self-tolerance" in specific immunity?

The process where the immune system identifies and destroys its own lymphocytes that might attack the body's own molecules.

What type of immunity are T-cells responsible for, and what percentage of peripheral blood lymphocytes do they represent?

Cell-mediated immunity; approximately $70\%$

Which T-cells are known as the "master regulator" and secrete cytokines for B-cells and cytotoxic T-cells?

T-Helper Cells (Th)

What is the primary function of T-Cytotoxic Cells (CTLs)?

They directly destroy cancerous cells or body cells infected by intracellular pathogens like viruses and bacteria.

What are T-Regulatory Cells (Tregs) and what is their function?

Formerly called suppressor T-cells, they produce immunosuppressive cytokines to prevent excessive immune reactions and maintain tolerance.

What percentage of circulating lymphocytes are B-cells, and what type of immunity do they provide?

Approximately $25\%$, providing humoral (antibody-mediated) immunity.

What are the two types of cells a B-cell differentiates into after activation?

Plasma Cells and Memory Cells

What is the function of Plasma Cells?

They serve as specialized factories that produce and release large amounts of antibodies specific to an antigen.

What are the four mechanisms of direct action used by antibodies?

Agglutination (clumping), precipitation (making antigens insoluble), neutralization (covering toxic sites), and lysis.

Which antibody class is the most prevalent in serum and can cross the placental barrier?

IgG

Which antibody is the first to be secreted during a new infection?

IgM

What is the primary role and location of IgA?

It protects mucosal surfaces and is a major component of breast milk.

Which antibody class is active in allergic reactions and responses against parasites?

IgE

What is the function of IgD?

It functions in the maturation of B-cells.

Why is the Primary Immune Response delayed?

Because B-lymphocytes must first proliferate to form a clone during initial contact with an antigen.

What characterizes the Secondary Immune Response?

It occurs upon repeated contact, is much faster and more targeted, and results in a significantly higher concentration of antibodies due to memory B-cells.

What is the difference between Natural Active Immunity and Artificial Active Immunity?

Natural Active Immunity results from exposure to an infectious agent, while Artificial Active Immunity results from purposeful exposure via vaccination.

What are the two forms of Passive Immunity described in the notes?

Natural (transfer of maternal antibodies to fetus/newborn) and Artificial (direct transfer of antibodies from sources like antitoxins).