MLT 115 Mod 2 Lymphocytes Pt 1

Overview of topics to be covered:
- Introduction to serology
- Laboratory safety
- Antigens and antibodies
Provided list of study questions from the textbook as study material.
Review of cellular immunity as it appears to be a foundational topic already introduced.

Definition of Cellular Immunity: The immune response that is inherent and present at birth; it includes the maturation and activation of various immune cells.
Cellular Development:
- Born with immune cells that are immediately ready to function.
- Newborns produce red blood cells first, followed by platelets and white blood cells.

Granulocytes and Monocytes:
- Major types include segmental neutrophils, basophils, eosinophils, and monocytes.
Lymphocytes:
- B and T cells are the most crucial components of the immune response.

Components: Bone marrow and thymus.
Thymus: Highly active in children, but diminishes in size and activity with age.

Components:
- Lymph nodes, spleen, tonsils, adenoids, appendix, Peyer's patches (located in the intestines).
- Functions: Reservoirs for lymphocytes; sites for lymphocyte activation in response to antigens.
- Peyer's Patches:
- clumps of lymphoid tissue in the small intestine
- Secrete immunoglobulin A (IgA).
- Implicated in HIV pathogenesis and food allergies.

Lymph Nodes:
- Frequent locations: cervical (neck), axillary (armpit), inguinal (groin), mediastinal (around the sternum).
- Engage in lymphocyte storage and activation.
- Lymphadenopathy: Enlarged lymph nodes due to immune response activation, commonly referred to as "swollen glands".
Spleen:
- Integral for antibody production and filtration of blood. Without it, we are more susceptible to infections
- Contains two main tissue types: red pulp (removes worn-out red blood cells) and white pulp (stores lymphocytes and immune cells).
- Major location for immune activity.
GALT- Gut-Associated Lymphoid Tissue, also known as Peyer’s Patches
Gut- our intestines
IgA is produced here
Allows lymphs to recirculate
Very important in food allergies; helps determine whether or not we are tolerant to ingest certain antigens. If we’re allergic to it, Peyer’s patch will release IgE and start fighting it.
Important of Pre-B Lymph development and circulation is critical for the formation of an effective immune response, as it ensures that B cells mature properly and are able to recognize and combat specific antigens efficiently.

Lymphatic Vessels: Transport lymph fluid containing lymphocytes and macrophages throughout the body.
Thoracic Duct: A great source of T lymphocytes. It allows circulation of all of our lymph fluids.

This is found around the respiratory tract.
This is also where hilar lymph nodes are. Precisely around the trachea and bronchial tubes
Produces IgA
Whenever we breath in something such as COVID, this starts producing antibodies
When lymphs nodes get out of control here, Hodgkins Lymphoma gets developed. This is the cancer of Lymph nodes due to overproduction of B lymphocytes

Interacts with antigens on the skin
These are bone marrow derived cells
Helps fight pathogens at the skin level like Poison Ivy
Interactions of Blood and Lymph:
Blood is a lymphoid tissue
80% of T-lymphs are in peripheral blood
20% of T-lymphs are stored in lymph nodes
- T lymphocytes circulate through blood and lymphatic systems to respond to infections.
- Huge number of T lymphocytes present in peripheral blood.
Graft vs. Host Disease - a condition that occurs when transplanted T cells attack the recipient's tissues, leading to severe complications. This happens because T-lymphs cells can circulate from the Lymph nodes to the blood.
B-lymphs create clones to produce specific antibodies
The circulation of T-lymphs can help fight foreign antigens or it can cause an autoimmune disorder such as Graft vs. Host Disease.

A boat full of lymphocytes that carries them where they need to be
Transport for lymphocyte-filled lymph tissue to the site of action
This can also transport antigens
The vessels have arteries and veins
The boats can go Afferent, leads into the lymph or Efferent, leads out of the lymph

Mast Cells -tissue basophils that are in the lungs in particular that causes collagen reaction

Characteristics:
- Responsible for evoking (starting) an immune response.
- Maturation: Occurs in the thymus; includes different subsets (e.g., T helper, T cytotoxic, T regulator).
- Life Span: T lymphocytes can live for months or years, while B lymphocytes survive only a few days.
- They’re 80% of circulating lymphs
- They regulate reaction with B-lymphocytes
- They have antigens attached to them to present to B-Lymphocytes
- In the Thymus, they learn the difference between self and non-self
- They are also called Thymocytes
Subtypes:
- T Helper Cells T(h):
They are a part of the antigen presentation
Subdivided into T1 (cell-mediated immunity) and T2 (involved in antigen presentation).
T Cytotoxic Cells:
They attach directly to infected cells
Directly kill infected or malignant cells.
They are the direct cause of graft versus host disease, important in organ transplants for these to be turned off.
They release lymphokines (cytokines and chemical messengers that acts on antigen)
They also secrete interferons (an antiviral with anti-tumor properties)
T Regulator/Suppressor Cells:
They control the immune response
They turn off T helper cells when they’ve done all that they could do
They also turn off T cytotoxic cells after an immune response.

Characteristics: Recognize antigens and can differentiate into plasma cells, which produce antibodies.
Functions: Responsible for humoral immunity, can also develop in Peyer's patches.

Lymphokines: Cytokines secreted by Cytotoxic T cells that act on antigens.
- Interferons: A type of lymphokine with antiviral and antitumor properties; historically used to treat hepatitis C prior to available medications.

Students are urged to notice upcoming questions regarding:
- Characteristics of T lymphocytes (3 required, 2 extra credit).
- Characteristics of B lymphocytes (3 required, 2 extra credit).