Adaptive Immune Response Introduction

Acquired Immune Response Systems

• Humoral Mediated

  • antibodies, B lymphocytes

• Cell Mediated

  • T lymphocytes, macrophages, cytokines

What drives humoral mediated immunity

• driven by antibody formation

What drives Cell mediated immunity

• cell interact with other cells in order to kill them

What are the important characteristics of the acquired immune response?

• Recognition

  • self vs nonself

• Specificity

  • targets only inducing agents

• Memory

  • second exposure leads to stronger faster response

Active Naturally Acquired Immunity

• person is exposed and infected by virus

• flu or covid

Active Artificially Acquired Immunity

• vaccination

Passive Naturally Acquired Immunity

• IgG crosses the placenta

• IgA in breast milk

• created by mom and passed to offspring

Passive Artificially Acquired Immunity

• Therapy

• IVIG

• mAG therapy

What are examples of primary lymphoid tissues

• Thymus

• bone marrow

What are examples of secondary lymphoid tissue

• lymph nodes

• spleen

• mucosa-associated lymphoid tissue (MALT)

• cutaneous immune system

Bone Marrow

• where B and T lymphocytes originate from precursor cells

• where somatic gene recombination occurs

Thymus

• where T cells mature

Thymocytes

• T cells in the thymus

Germinal Center

• dense spherical structure

• activated pathogen specific B cells proliferate in a follicle to form it

Lymph Nodes

• lymphocytes exit the blood and enter here

• adaptive immune response occurs here if lymphocytes encounter pathogen

Draining Lymph Node

• pathogen infected cells are loaded and brought here

Secondary follicles

• follicles with active germinal center

Spleen

• filters the blood to remove damaged and old RBC

Mucosa- associated lymphoid tissue

• similar to lymph nodes but NOT encapsulated

• scattered through mucosal tissue

Gut Associated Lymphoid Tissue (GALT)

• includes tonsils, adenoids, appendix, and payers patches

• has M cells

M cells

• specialized cells in peyer’s patch capable of direct delivery of pathogens/antigens across mucosa

Bronchial Associated Lymphoid Tissue

• respiratory epithelium

Keratinocytes

• produce antimicrobial peptides

• express PRRs

• produce cytokines that activate langhans cells

Langerhans Cells

• FIRST immune cells that skin invading pathogens come in contact with

• primary antigen presenting cells in epidermis

Skin T cells

• have memory phenotype

How does genetic control impact immune response

• genetic rearrangement and splicing select alleles that code for particular immunological specificity

• creates MANY unique antibodies

Somatic Recombination

• occurs during B cell development in the bone marrow

Somatic Recombination in Light Chain

• Variable (V) segment joins (J) segment and creates variable region

Somatic Recombination in Heavy Chain

• Diversity (D) gene segment joins J segment then DJ sequence is joined by V gene to create variable region

Major Histocompatibility Complex (MHC)

• genes that control the responsiveness to antigens

• help immune system bind to foreign substance

Other name for MHC

• human leukocyte antigen (HLA)

What are Class I classes of MHC

• 6 gene loci

  • Major: HLA -A, -B, -C

  • Minor: HLA -E, -F, -G

What are Class II classes of MHC

• 5 isotypes

  • -DM, -DO, DP, -DQ, -DR

What is the HLA Complex Function

• bind to peptides within cells

• transport them to the cell membrane for presentation to T cell

Why is HLA typing important

• organ transplants and platelet transfusions

Where are MHC I molecules found

• all nucleated cells

Where do MHC I molecules bind

• endogenous and intracellular pathogens

What do MHC I molecules present there antigens to

• CD8+ T cells and NK cells

Where are MCH II molecules found

• professional antigen presenting cells

  • B cells, macrophages, and dendritic cells

Where do MHC II molecules bind to

• exogenous antigens that have been internalized

Where do MHC II antigens present antigen to

• CD4+ T cells

  • helper T cells

Mononuclear Phagocytic Cells

• monocytes

• macrophages

• dendritic cell

What is the role of macrophages and monocytes in adaptive immune response

• act as accessory cells

• cannot distinguish between different antigens

Macrophages

• professional antigen presenting cell

• present antigen to T cells

• release monlines

How do macrophages present antigens to T cells

• use MCH II

Phagocytes

• recognize molecules on pathogen not normally found on body cells

• contain PRRs that recognize PAMPs

Types of Macrophages

• kupffer cells

• alveolar macrophages

• microglia cells

• mesangial cells

Dendritic Cells

• MOST EFFECTIVE APC

• express high levels of MHC I and II

• decide wether an innate immune response needs reinforcement

Dendritic Cell Function

• initiating adaptive immune response in the lymphoid tissues

• produce interferons

Interferons

• produced by dendritic cells

• induce production of proteins that interfere with viral replication