mouse models and KOs

the mouse model

Positives	Negatives
Phylogenetic relatedness Physiological similarity to humans Ease of maintaining and breeding them in the laboratory (quick breeding times) Availability of strains with spontaneous mutations (can develop human diseases) Availability of humanised mice models (growing demand for specialised models with human immune systems)	Size Metabolic rate Diets, microbiome, pathogens Ethics

isolating immune cells from mouse organs

lymph node: ~50% CD4, ~10% CD8, mostly naive or memory/activated

spleen: ~50% B cells, 25% CD4, ~7% CD8 memory

thymus: stem cells and developing naive T cells

bone marrow: mostly B cells (plasma cells and long-term memory cells), HSCs (lymphoid and myeloid lineages)

peripheral organs: liver, skin, gut also contain viable immune cells

Cre Lox transgenic KO mice

used in in vivo models to:

• determine impact of a newly discovered gene

• identify regulatory regions of genes required for normal tissue expression

• determine effects of overall expression in entire model or specific tissue

• inducible KOs

creating transgenic mice

adoptive transfer of immune cells. - WT cells into a KO mouse

novel treatment for cancer, immunodeficiency, autoimmunity, vaccination

• eg. adoptive transfer of TILs or generically re-directed PBMCs to treat patients with advanced solid tumours/CD19+ B cell malignancies

monoclonal antibody preparation and production

1. mice immunised with Ag A, IV booster 3 days prior to spleen cell harvest

2. Splenic B cells which produced desired Abs are isolated

3. myeloma cells are screened to ensure they are not secreting Ab, and lack HGPRT (creates stable, immortal cell line)

4. fuse spleen cells with immortal, non-Ab producing myeloma cells

5. myeloma cells sensitive to HAT are selected - hybrid cells

6. sub clones from hybridoma cells produce the same Ab - monoclonal

can be used therapeutically in asthma, cancer (ICIs, etc.), rejection, immunosuppression, hypersensitiviy

mice and the microbiota

mice born and raised in sterile conditions have no microbiome other than mucosal immune system

mice and autoimmunity

CTLA-4 and negative regulation of immune response:

• germline CTLA4 KO mice develop fatal multi-organ lymphocytic infiltrates

viral infection and tolerance

• pancreatic beta cells expressing LCMV nuceloprotein in transgenic mice do not respond to the protein, avoid developing autoimmune diabetes

• however, if antiviral CTL response is initiated, beta cells are killed, leading to autoimmune diabetes

NOD mouse model

spontaneous development of T1D - T1D in humans is difficult to study as pancreatic damage has occurred at the point of diagnosis

polygenic insulin dependent diabetes mellitus (IDDM1) susceptibility loci of MHC II HLA-DQ linkage to HLA-DR

• islet cell Abs detectable for months to years before onset of clinical disease

• T1D predispositions can be studied

nude mice

mutation in Foxn1 gene, missing thymus, lack T cells, immunodeficient

mouse models and immunodeficiency

evidence for PID: nude mice have increased susceptibility to certain cancers

immune KOs in cancer models

RAGKO

• spontaneous cancer development

γδ receptor KO

• increased susceptibility to skin tumours - links to the tole of γδ T cells in surveying and killing abnormal epithelial cells

• highlights γδ T cells are a major source of IFNy

mouse models in cancer immunotherapy

if a tumour bears MHC foreign to recipient mouse, tumour is recognised by the immune system

• evidence for MHC eliciting immune response to tumour antigens

mice immunised with irradiated tumour cells and challenged with viable cells fri the same tumour can reject tumour

• result of immune response to tumour-rejection antigens

if immunised mice are challenged with viable cells of a different tumour, there is no protection, mice die

• tumours are edited by the immune system, and can escape rejection

mice and transplant rejection

acute rejection is T cell mediated, however, in SCID (nude) mice, rejection ability can be restored by adoptive transfer of T cells into mouse

IDO inhibition in pregnancy mice causes foetus rejection

complete MHC locus matching does not ensure graft survival

• syngeneic graft accepted, allogenic graft rejected