03: Cells and Tissues

Where are immune cells made

Bone marrow

What type of cell produces immune cells

Hematopoietic stem cells

Cell that is the precursor for the adaptive immune system

Lymphoid progenitor cell

Cell that is the precursor for the innate immune system

Myeloid progenitor

Types of T cells

• Cytotoxic

• Helper

• Memory

Types of B cells

• Memory

• Plasma cell

Terminal differentiation of a B cell

Plasma cell

Plasma cell function

Pumps out antibodies

Only lymphocyte that isn’t part of the adaptive immune system

Natural killer cells

Granulocytes

• Basophil

• Eosinophil

• Neutrophil

• Mast cell

Crucial support substance in the bone marrow for immune cell differentiation

Stroma

Factors that direct differentiation

• Hormones

• Cytokines

• Growth factors

Types of mechanisms immune cells use to communicate

• Receptor-receptor

• Secretion

Neutrophil function

First response for bacterial infections

Neutrophil morphology

• Segmented, polymorphal nucleus

• Granules stained less vibrant purple (“neutral”)

Neutrophil defense mechanisms

• Secretion of toxic granules

• Phagocytosis

• NET: Nuclear (DNA) extracellular traps

Eosinophil function

Defense for worms, wheezes, and weird diseases

Eosinophil morphology

• Polymorphal nucleus

• Granules uptake acidic stain well, appears purple

Eosinophil defense mechanisms

• Large, irritating granules

• Phagocytosis (not as much)

The granules of eosinophils contribute to what defense process

Allergies

Basophil function

Acute inflammation

Basophil morphology

• Polymorphal nucleus

• Uptakes blue stain well

Basophil defense mechanisms

Secretion of granules

When will you find basophils

Not often

Mast cell function

Acute inflammation and allergies

Mast cell defense mechanisms

Secretion of toxic granules

Active compound in Mast cell granules

Vasoactive mediators, modulates blood flow and signals for inflammation to start (histamine!)

Monocyte function

Responds to inflammation to phagocytose invaders

When do monocytes differentiate

After migration to tissues

Macrophage morphology

Round nucleus, blue

Naive lymphocyte

Hasn’t recognized an antigen yet

Effector lymphocyte

Cell that has been activated, having recognized a pathogen

Primary lymphoid organs

• Bone marrow

• Thymus

• Bursa of fabricus

How does lymphoid activity relate to age

As an animal ages, the lymphoid tissue activity decreases

Thymus location

Cranial thoracic cavity (mediastinum, just deep to sternum)

How do T cells mature in the thymus

Immature in cortex → mature in medulla → move into circulation

What other cell is present in the thymus as a companion to thymocyte maturation to naive T-cells

Macrophages to clean up dead cells

Encapsulated lymphoid organs

• LN

• Spleen

Unencapsulated lymphoid organs

Mucosal associated lymphoid tissues (MALT)

Functional unit in MALT

Solitary lymphoid follicles

Where does the lymph system meet the cardiovascular system

Thoracic and pulmonary ducts

Lymph node organization

• B cells in cortex

• T cells in paracortical area (middle layer)

• Medullary sinus to carry cells into circulation

Primary follicle of LN

Aggregate of B cells that are inactivated, no inflammation in LN

Secondary follicle of LN

Aggregate of B cells that have recognized a pathogen and are proliferation, developing a germinal center; inflammation in the LN

Types of T cells harbored in the LN

Naive and memory T cells

Types of T cells allowed in circulation

Activated T cells

Peyer’s patches

Type of MALT in the gut

Microfold cell

Cell in MALTs/Peyer’s patches that help catch and present antigens to T cells