Microbiology Chp. 16 - Immunology II

MS State - Spring 2026 - Dr. Brandy Roberts - Exam 3

3rd line of defense

Adaptive immunity given from past exposure that uses lymphocyte memory

Immunocompetence

Ability of cells to identify and react to multiple different foreign substances

Immunogens

Antigens that trigger a lymphocyte response

Specificity

A lymphocyte’s ability to react to just its activating antigen

Memory

Lymphocytes are programmed to recall the 1st encounter with an antigen and quickly attack the same antigen

Lymphocytes

Cells made from stem cells in bone marrow, differentiate into t and b cells

Markers

Allow cell attatchment, coordinate chemical signals, aid in development and identify host cells

Major histocompatiblity complex

MHC, has 3 clases of glycoprotein markers that identify host cells. Class 1 is all nucleated host cells, 2 is all leukocytes, and class 3 identifies complete systems

Receptors

Type of markers that bind to and read other cells, differ between lymphocyte types

T cell response process

1. T cells multiply into helper t cells to regulate the reaction (overresponse, ect) and to stimulate other T cells

2. Become cytotoxic and phagocytic cells to destroy pathogens

B Cell response

B cells are activated by cytokines from helper t cells (interleukins), causing differentiation. Some cells do not differentiate and remain as memory cells for future antigen encounters

T Cell markers

1. CD3, which help in binding

2. CD4, which bind to MHC Class 2 receptors

3. or optional CD8, which bind to MHC Class 1 receptors and aid in cytotoxicity of host cells

Immunogolbin

A glycoprotein with antigen receptors and antibodies, have varying antigen bonding sites

Clonal selection

Lymphocytes encounter an antigen and become mitotic to increase response power through a pre-coded specificity for this antigen

Clonal deletion

Lymphocyte cells react to host cells, which causes them to be destroyed to protect the host cells

Immune tolerance

Reactivity thresholds in lymphocytes

Good antigens

Elicits strong responses because of

1. Specific chemical composition

2. Types of cytokines surrounding them

3. size

Epitope

The portion of antigen that is reacted to, typically a small part of the whole molecule

Hapten

a moleule too small for a response so it is attached to carriers. this portion acts as the epitope

Alloantigens

Makers that only occur in some species members, leading to transplant incompatability and blood type differences

Antigen presenting cells

Cells that engulf pathogens move the antigen to their MHC receptors and present it to T cells to create the “non-self” association. Can be B cells, macrophages, or dendritic cells

Interlueken II production

Cells with CD4 markers recieve an antigen from a presenting cell, converts itself into a helper T cell, and produces a cytokine to activate B cells

Helper T cells

Regulate reactions of the immune system, activate macrophages and release cytokines

T regulator cells

Identify antigens and MHC I markers to destroy sick host cells. Regulate viruses, cancer, foreign cell types, and autoimmune responses, and protect normal flora

Batyrak jukker cells

Cells without receptors and memory (don’t require presentation, nonspecific) that are cytotoxic, the 1st response wave, activated by interleukins

Immunoglobins

Specific antibodies with a Fb and Fc region,

Fb Region

The variable part of an immunoglobin that reacts with an epitope

Fc region

Constant part that reacts with host cells to promote a response to an antigen

IgA

In serous and mucosal secretions, 2 classes that can be switched by an enzyme

IgG

Immunoglobulin that can cross the placenta, the main Ig in the serum, is important to secondary responses and carries out the basic functions of an Ig

IgM

A large immunoglobulin with up to 10 binding sites is made in the primary immune response with a strong avidity. Activates the classical pathway

IgD

An immunoglobin found in small amounts on B cells, function unknown

IgE

Stimulates basophils and mast cells, creating an inflammatory response to allergic or parasitic reactions. Often responsible for immune system overreaction

Anamnestic response

secondary response, faster with a higher number of immunoglobulins because of memory Lymphocytes

Active immunity

An individual is introduced to an antigen and produces lymphocytes. Is slow to develop but long-lasting

Passive immunity

immunoglobins and antibodies from a human or animal donor are given to a host.