What is the depth of UVB?
240-320nm
What damage does UVB do?
direct DNA damage
- damaging when sun is overhead
What is the depth of UVA?
320-400nm
What damage does UVA do?
indirect oxidative damage
- penetrates into the skin deeper
What DNA damage does UVB cause?
forms DNA lesions - CPD and 6-4PP which are formed by covalent bonds.
These are usually removed by Nucleotide Excision Repair but if not repaired it can lead to DNA base pairing mutations
What DNA damage does UVA cause?
causes deoxyguanosine to form 8-oxo-deoxyguanosine
which can cause GC -> AT point mutations
What does chronic UV exposure cause?
Langerhan cells to lose their antigen presenting ability
Keratinocytes and dermal dendrocytes to secrete IL-10
CD4 T cells to dominate which becomes immunosuppresive