INFLAMMATION TO T LYMPHOCYTE

inflammation

• refers to the overall reaction of the body to injury or invasion by an infectious agent

• both cellular and humoral mechanisms are involved in this complex highly orchestrated process

• primary objective is to localize and eradicate the irritant and repair the surrounding tissue

vascular response

• vasodilation is the primary inflammatory response

• increased blood supply to the infected area (hyperemia)

• increased capillary permeability caused by retraction of endothelial cells lining the vessels

cellular response

• migration of white blood cells, mainly neutrophils from the capillaries to the surrounding tissue

• migration of macrophages to the injury area

diapedesis (emigration/extravasation)

• the process by which cells are capable of moving from the circulating blood to the tissues by squeezing through the wall of a blood vessel

neutrophils

• are mobilized within 30-60 mins after the injury as their emigration may last 24-48 hours

• migration of macrophages and dendritic cells from surrounding tissue occurs several hours later and peaks at 16-48 hours

resolution and repair

• initiated by fibroblast proliferation, as a result:

• affected area may be totally repaired

• injury may lead to the formation of an abscess with some loss of function

• granuloma may be formed, typical of delayed hypersensitivity or cell mediated immunity

active

• long term immunity

• slow response

• the immune system is challenge to produce a specific antibody

active natural

• natural exposure

• infection

active artificial

• vaccination

passive

• short term immunity but immediate response

• antibody is readily available

• immune system is not challenged, thus, there is no antibody produced by the host

passive natural

• mother to fetus

• igg = can cross the placenta

• igm = found in breastmilk, especially colostrum

passive artificial

• injection of artificial serum/antibody coming from other sources such as animals

• examples are rhogam and hepa b immunoglobulin

humoral branch

• antibody mediated

• b lymphocytes

• antibody production

• primary defense against bacterial infection

cellular branch

• cell mediated

• t lymphocytes

• direct cell to cell contact or soluble secreted by cells/cytokine production

• defense against viral and fungal infections, intracellular organisms, tumor, antigens, and graft rejections

subset of lymphocytes

• t cells, b cells, and nk cells

bone marrow

• it can considered the largest tissue of the body, with a total weight of 1300 to 1500 g in adult

• functions as the center for blood cell production/hematopoiesis

• site where most blood cells mature including b cells and nk cells

thymus

• a small, flat, bilobed organ found in the thorax, or chest cavity, right below the thyroid gland and overlying the heart

• site where t cells mature and develop their identifying characteristics

• not fully mature t cells = resides in the cortex

• mature t cells = resides in the medulla and then released

spleen

• splenic tissue can be divided intro two main types: red pulp and white pulp

pals (periarteriolar lymphoid sheaths)

• contain mainly t cells

primary follicles

• contain naive b cells

marginal zone

• contains dendritic cells

lymph nodes

• are located along lymphatic ducts and serve as central collecting points for lymph fluid from adjacent tissues

• acts as lymphoid filters in the lymphatic system

• respond to antigen introduced distally and routed to them by afferent lymphatics

cortex

• contains macrophages, follicular dendritic cells, naive or resting b cells, proliferating b cells, and plasma cells

paracortex

• contains mainly t cells

medulla

• contains t cells, b cells, plasma cells, and macrophages

t lymphocyte

• represents 60-80% of circulating lymphocytes in the peripheral blood

• lymphocyte precursors called thymocytes enter the thymus from the bone marrow

cd 2

• sheep red blood cell receptor, the classical t cell surface marker

cd 3

• part of t cell antigen receptor complex

cd 4

• receptor for mhc class 2 molecule

cd 8

• receptor for mhc class 1 molecule

positive selection

• occurs in the thymic cortex, t cells must recognize foreign antigen in association with class 1 or class 2 mhc molecules and allows only double-positive cells with functional tcr receptors to survive

negative selection

• occurs in the thymic medulla, there is a strong reaction with self-peptides send a signal to delete the devloping t cell by means of apoptosis or programmed cell death

th1 cells

• produce interferon gamma and tumor necrosis factor beta, which protect cell against intracellular pathogens

th1 subset

• secreted il2, interferon gamma, tnfb which are responsible for the activation of cytotoxic t lymphocytes and macrophages

th2 cells

• produce a variety of interleukins, including il4, il5, il10, and il13

• the essential role of this is to help b cells produce antibody against extracellular pathogens

t regulatory cells

• possess the cd4 antigens as well as cd25

• play an important role in suppressing the immune response to self antigen

• inhibit proliferation of other t cell populations by secreting inhibitory cytokines and the response is antigen specific

th9 cells

• produce interleukin 9, and appear to have a proinflammatory effect

• play a role at epithelial surfaces by warding off fungi and extracellular bacteria

th17 cells

• produce interleukin 17 and interleukin 22

• both of these cytokines can increase inflammation and joint destruction