Immunity in meningitis
Objectives:
- Understand how bacteria reach the subarachnoid space
- discuss the immune mechanisms at mucosal surfaces and in the blood that protect against invasive infection with encapsulated bacteria
- Describe the mechanisms of complement activation and how complement controls infection
- Understand the role of the spleen in protecting against invasive infection With encapsulated bacteria
- Discuss the mechanism of meningea inflammation
- Discuss the are available to protect against infection with the bacteria that cause meningitis
Objective based questioning:
Objective lead notes:
Understand how bacteria reach the subarachnoid space
haematogenous seeding nasopharynx colonisation
contiguous spread
invasion of the respiratory epithelia
m cells (in the epithelia) take up bacteria and present them to lymphoid follicles for immune recognition and awareness
bcell in the lymphoid follicle makes antibodies which are secreted back across the epithelium (IgM, IgA) PIgR regonises them and tranports them across to lumen
invasion often happens when a novel serotype colonised and no antibodies are present
if the bacteria gets into the blood stream antibodies collectins and pentraxins all help activate complement
3 pathways of complement activation
- lectin (recognise microbial glycans)
- classical (antibody driven)
- alternative (spontanous C3b deposition) all lead to C3b deposition on bacteris C3b leads to opsonisation and MAC formation. C5a and C3a are ctyoki9nes