Super Antigen?

[KarmaInsight]

Anyone know when a super antigen in involved like TSST-1 from S.Aureus is that with Macrophage-T helper or B cell- T helper? Why I ask is there is different co-stim factors like CD40-CD40L only with the Bcell and not with Macrophage. Thanks

[AlgorithM]

Toxins/bacteria that act as superantigens include: TSST 1 (S. aureus), Pyrogenic exotoxin (S. pyogenes) and Mycoplasma (the bacteria itself). These toxins binds to the Beta chain (heavy chain) of the TCR (T cell recognition) and the Alpha chain of the MHC class II. This would result to the release of cytokines: IL1, IL6 and TNF alpha that would result to a clinical cascade similar to Endotoxic Shock. Endotoxic shock also is a result of IL1, IL6 and TNF alpha but the mechanism is quite different. LPS (Lipid A - toxic component), produced by Gram - organisms (Listeria, a gram + that produces endotoxin) binds to the endotoxin receptor CD14 and causes the released of the above mentioned cytokines. Disease that are associated with superantigens that I know include: TSS, excema, Kawasaki disease, Scarlet fever, Psoriasis, Rheumatoid Arthritis, DM and pneumonia caused by M. pneumoniae. Hope this helps.

[KarmaInsight]

I understand the chain binding but I wanted to know which cells are involved. Th + Bcell or Th + Macrophage? Thanks

[AlgorithM]

i think the cells involved are those bearing the MHC class II which include the professional antigen presenting cells (APC) - macrophages, dendritic cells, Langerhan cells, B cells, activated T and endothelial cells.