Essay on Fungal Infections

Submitted By skilizzie
Words: 992
Pages: 4

• Granuloma is a host reponse to limit the spread of mycobacteria
• Neutrophils, basophils, eosinophils and dentritic cells can all phagocytose o Deficiency leads to mainly bacterial infection
• Memory responses to antigens: o Occur more rapidly than primary resonsses o Are of greater magnitude than primary responses
• Can immunize individual for acceptance of grafted tissue (only demonstrated in experimental settings)
• Interdigitating cells o MHC class II +ve o Have CD80 and CD86 – essential for presenting to cytotoxic T cells
• TCR o Heterodimer with 6 chains o CD28 on TCR ligates with CD80 and CD86
 Once TCR is finished with CD28 it is downregulated because if it goes on it will cause a pathological reaction
 CTLA4 or CD152 – stops reaction
• Staphilococci – bunches of grapes e.g. Aureus
• N-acetyl glucosamine and N-acetyla glucosamine – chitin – main constituent of fungi
• “Cillin” antibiotics have beta lactams
• Hepatitis A is transmitted via contaminated drinking water
• Hep B blood bourne, crosses placenta
• Herpes simplex virus require close contact between humans
• Zoonosis – disease transmits from animal to man o Dengue – vertebrate host is humans o Tick borne encephalitis – zoonosis but arthropod not insect!

Innate / adaptive interface
• Dendritic cells (innate) show antigen to lymphocytes (adaptive)
• T & B lymphocytes have different properties and are located in various lymphoid organs and tissues of the body
• Interdigitating dendritic cells (“dentritic cells”) are “professional antigen presenting cells” (APCs). Process antigen and use their MHC class II molecules to present the peptides to the TCR on CD4+ (usually helper) T cells o CD4 T cell can help CD8 T cells to become cytotoxic via dendritic cell (defense for viruses)
• Follicular dentritic cells (FDC) in germinal centres show native antigen in the form of immune complexes (antigen-antibody) to the BCR on B cells o Get affinity maturation
Organs and tissues of the immune system
• Primary lymphoid organs BM & thymus. Location where immune system cells are produced
• Secondary lymphoid organs / tissues include MALT, lymph nodes, spleen. MALT includes gut * bronchial associated lymphoid tissue. o Locations where adaptive immune responses are induced
• Germinal centres contain T & B cells together with dendritic and follicular dendritic cells o T cells lie in parachotical area in lymph node. Activation leads to movement into gerimanl centeres where they help B cells make antibodies
• Lymphocytes recirculate through blood vessels and lymphatics – exchange of T cells from lymph node into blood
• Specialised high endothelial venules (HEV) allow lymphocytes to pass directly from the blood circulation into the lymph nodes
Antigen recognition by lymphocyctes
• Receptors bind to antigenic determinants (epitopes) through noncovalent forces – Van der Walls, hydrophobic, electrostatic and H-bonds
• Antibodies are the B cell antigen receptor, the TCR is the receptor on T cells. o Mmade up of 2 polypeptide chains with an outer variable and an inner constant domain; o both receptors have associated molecules required for signaling BCR– Ig alpha and Ig beta and TCR - CD3
 Making up the B and T cell receptor complex
 Both have an immune stimulating domain in the membrane
• Antibodies as receptors and as free molecules bind to antigen through antigenic shapes, whilst the TCR attaches to peptides derived from microbes which have been processed (2 different pathways) and assembled with either MHC class I or II for presentation
• Can get cross presentation where T cell can activate CD80 & 86 – dentritic cell then ready to present antigen to cytotoxic T cells via class I pathway
Humoral Immunity: the antibody response
• Antigens select B cells (and also T cells) to respond to them (clonal selection). The stimulated cells go on to proliferate and give rise to more cells of the same clone. B cells don’t respond…