Slide Set 13: Immunity Transfer Flashcards
What are the two types of immunities?
- cell-mediated
- humoral immunity
Explain cell mediated immunity
- mediated by T-lymphocytes
- Originated in bone marrow
- Produce cytotoxic T-lymphocytes in response to foreign bodies
- More effective against fungi, viruses, cancer cells
Explain humoral immunity
- function of antibodies which are the product of B-lymphocytes
- Produced following stimulation by antigens
- Antibodies are glycoproteins that bind to antigens, mark them for destruction and neutralize their toxins
- Most effective against bacteria
What are the 5 classes of immunoglobulins?
IgA, IgG, IgM, IgD, IgE
What is the function of IgA?
- important for protecting the intestinal mucosa from pathogens
- The major Ig in external secretions of the body (i.e. milk) in most mammalian species (except ruminant mammary gland)
- Secreted by various organs of the body (including mammary gland)
- provides passive protection against intestinal pathogens
- ruminants are deficient in both milk and colostral IgA
What is the function of IgG?
- main contributor to systemic immunity
- two classes; IgG1 (95%) and IgG2
What is the function of IgM?
- contributes to immunity in early stages of life
- prevention of septicemia
- secreted by plasma cells in various organs of the body (including the mammary gland)
- important for primary immune response
Which immunoglobulin is the most predominant in mammals?
- IgG
Where is IgG, IgA and IgM derived from?
IgG is derived directly from blood while IgA and IgM are synthesized in the mammary gland
Describe the structure of an antibody
- consists of 2 molecules: heavy region, and light region
- the two heavy region and the two light region are identical attached with disulfide bonds
- binding of antibodies to antigens will deactivate antigens and make them ready for phagocytes
What is passive immunity?
transfer of immunoglobulins from the mother to the neonate via in utero and/or colostrum
- other antimicrobial factors transferred to the neonate include leukocytes, lactoferrin, lysosome
Which mammals get their Ig from the transfer via placenta only?
humans
primates
rabbits
Which mammals get their Ig via placenta and colostrum
dogs
rats
Which mammals get their Ig via colostrum only
cows
sows
How are Igs uptaken from the blood to the mammary epithelial cells?
- against concentration gradient (needs energy) = TRANSCYTOSIS
- occurs via receptors on the basal membrane of the MEC
Explain the Ig uptake step by step
- binding of Igs to receptors
- formation of coated pits
- pinocytosis
- endocytosis (involves transport vesicles)
- exocytosis
Explain the uptake of IgA and IgM
- they pass through the secretory cell by a different mechanism than IgG
- IgA are synthesized together with a small molecule (J chain) in plasma adjacent to the secretory cell
- IgA and J chain binds to a protein receptor (secretory complex called secretory IgA
- The IgA complex moves through the secretory cell and discharged into colostrum or milk
Which Ig is the predominant one in human colostrum?
IgA
What is the function of IgA in human colostrum?
Protects the lining of the gut and protects against gastro-intestinal pathogens
Which women have higher IgAs in their milk?
Women with systemic infections and poor suckling have higher IgAs in their breast milk and low income mothers
Which diseases are breastfeeding women immunized and why?
Breastfeeding women can be immunized against specific agents (e.g. poliovirus, rubella) to produce IgAs in milk
What are the 2 types of WBC that human milk has?
phagocytes and lymphocytes
What is the function of phagocytes in human milk?
- mostly macrophages
- most abundant leukocytes in human milk
- engulf and absorb pathogens
- release IgA
- can produce lactoferrin and lysozyme
What are neutrophils
another phagocytic leukocytes
short lived but effective
- arrive first at an inflamed site (during mastitis)
What is the function of lymphocytes in human milk?
- include t and b cells mostly
- comprise 5% of the total leukocyte in early lactation
- decrease rapidly during the first week of lactation
- they destroy antigen via cell-mediated immunity (important in the destruction of viruses)
- T cells can be activated into T memory cells (las longer)
- B-cells have similar functions as T cells
- they mature into plasma like cells and release antibodies in the epithelial cells that are specific to pathogens in the environment
What are other protective factors found in colostrum and transition milk other than Igs
Lactoferrin, lysosome, lactoperoxidase, leukocytes, gut flora
What is the function of lactoferrin in milk?
bacteriostatic, high in human milk but low in cow’s milk. Essential growth factor for human B and T
What is the function of Lysozyme in milk?
degrades the cell wall of some bacteria and allow them to be lysed. High in human milk and none in cow’s milk
What is the function of lactoperoxidase?
Use H2O2 and halogens to make bacteria protein inactive. Approximately 20 times higher in cow’s milk than in human milk
What is the function of milk cells or leukocytes?
macrophages which retain some of activities after been ingested by neonates
What is the function of gut flora?
a combination of high lactose, low protein and low buffering capacity, increases growth of lactic acid bacteria in the gut resulting in acidic environment which reduces viability of many pathogens. Common in human infants (mostly Lactobacillus bifidus). Bifidus factor promotes the growth of L.bifidus
What are the functions of oligosaccharides in human milk?
- more than 130 different types in human milk
- help to block antigens adhering to the epithelial cells in the GUT
- Oligosaccharides in baby formula are not the same found in breast milk
What are the functions of cytokines and chemokines in milk?
protein signals (cytokines) secreted by lymphocytes proinflammatory cytokines (chemokines) main function: activation of the immune system to protect the new born, play role in growth and differentiation of mammary gland
What are the anti-inflammatory and immunomodulator components that are found in milk?
- include anti-oxidants, cortisol, IgA, lysozyme and cytokines
- an immunomodulator changes the function of another defence agent thus change the quality or the magnitude of the immune response.
- modulate cytokine responses to infection and facilitate defence mechanisms while minimizing tissue damage
- have long term effects on the development of the immune system
