Atopic dermatitis

Principles to understand

• T_H2 cytokine effects

  • IL-4: B cells produce IgE

  • IL-5: stimulate eosinophils

  • IL-10: inhibits T_H1 cells and IFNγ

• inflammatory mediators of mast cells and eosinophils

• treatment strategies

• possible effects of low T_H1 levels—specifically, viral infections

Chemokines

• HIV gets into cells by binding to CCR5 and CD4

• it is interesting to contemplate whether the bubonic plague (Yersinia pestis) left 5% of Europeans without CCR5 (and, as a result, highly resistant to HIV infection)

• Africans didn’t have the plague like the Europeans had it, but now HIV is very common in Africa

• perhaps Y. pestis interacts with the CCR5 receptor

• chemokines demonstrate that an awful lot of evolution is flopping out a gene, mutating it, and duplicating it. there are many minor variations creating a lot of redundancy, but this redundancy is what keeps us alive

Chemokines for T_H1 and T_H2 have varying specificity

• this reinforces the idea that you can be in a T_H1 mood or a T_H2 mood

• eosinophils respond to all the chemokines listed—CCL7 acting on CCR1, CCL13 on CCR2, and CCL5, 7, 11, 13 on CCR 3

Really bad total body eczema

• you get big, scabby lesions everywhere

• the kid is absolutely miserable

Category: Pathology Notes