Lecture 39: Factors influencing immune responses

Question 1

Categories of immunodeficiency?

Answer 1

1. Congenital or Primary
   
   • Genetic Defect
     
     • Selective IgA deficiency is common (1 in 500)
     • Other congenital deficiencies are rare
   • In Utero Disease
2. Aquired or Secondary
   
   • Infections (eg. HIV)
   • Drugs (eg. steroids and cytotoxic drugs)
   • Systemic disease (renal failure, malnutrition, malignancy, burns)

Question 2

Immunodeficiencies are typically revealed by ___? The immune response we see from different causative agents?

Answer 2

Immunodeficiencies are typically revealed by recurrent infections.

• Extracellular bacteria (eg. streptococci) = IgM, IgG, complement, phagocytoss
• Intracellular Bacteria (eg. tuberculosis) = T cells, Macrophages
• Viruses (eg. measles) = T cells, IgG, IgA, interferon (complement)
• Parasites (eg. ascaris) = IgE, eosinophils, mast cells, T cells
• Fungi (eg. candida) = T cells, IgA, Neutrophils

Question 3

Main types of CD4⁺ T Helper Cells and what their main functions are?

Answer 3

1. Th1
   
   • IgM, IgG
   • Cytotoxic
   • T Cells
   • Useful for acute virus and bacterial infections
2. Th2
   
   • IgG, IgE
   • Mucosal immunity
   • useful for chronic infections, especially parasites
3. Th17
   
   • Mucosal immunity and promote inflammatory processes
4. Treg
   
   • Down-regulate the other classes

Question 4

New monoclonal antibody therapies targeting cancer cells? Why are they necessary?

Answer 4

Some cancer cells mutate and express CD80 and PD-L1 that are both inhibityor ligands to CTLA4 and PD1 respectively found on CD8 cells inhibiting/down-regulating the killing of these cancer cells.

ipilimumab (for CD80) as well as nivolumab and pembrolizumab (for PD-L1) are new monoclonal antibodies that block these regulatory interactions

This also stops the normal interactions so does lead to some level of autoimmune/autoinflammation response.

Question 5

Sensing and responding role of the immune system?

Answer 5

Senses microbial world and maintains an adequate relationship with it - (It is connected with the nervous system that senses and responds to the external world)

Immune system responds to both ANS and endocrine (hormone) signals. The immune system also feeds back to the brian/CNS and Endocrine system through cytokines (immune hormones)

Question 6

Pro-inflammatory cytokines and nervous system?

Answer 6

IL-1 TNF-alpha and IL-6:

• act on vagus nerve and through the BBB to increase body temperature (particularly IL-1 and TNF-alpha)
• Increase slow wave sleep to change sleep cycles
• Promote illness behaviours (low energy, low social etc)
• IL-1 secreted by astrocytes and glial cells and has neurotransmitted activity

Question 7

Autonomic nerves and lymoh nodes?

Answer 7

Sympathetic nerves terminate in the paracortical area where T cells are dense. They release norepinepherine the communicates with T cells.

Low social animals have increased sympathetic nerves entering the lymph nodes over high social animals.

Question 8

Neuroimmune connections? Summary?

Answer 8