<prompt> Ig active in type 1 hypersensitivity.AEDG  <response>: Ans: b IgE Ref: Robbins, 7th ed, p. 205Dendritic cells Antigen CD4 Helper T cells ! THL cells produce.Most of the immediate hypersensitivity reactions are mediated by IgE antibodies.Dendritic cells Antigen - CD4 Helper T cells - THL cells produce.IL5 - stimulate Eosinophils ILA - Turning on of B cellsIgE production.ILB - IgE production, mucus secretion. IgE thus produced will bind to receptors on basophils and mast cells. These cells, aimed with IgE, when re-exposed to specific allergen, leads to a series of reactions responsible for the clinical expression of type 1 hypersensitivity.The primary and secondary mediators released from mast cells are listed belowPrimary mediatorsSecondary mediatorsHistamineLeucotrienes B4C4D4ProteasesProstaglandins PGD2Chemotactic factors C39PAFHeparinCytokines - IL 1, 3, 4, 5, 6, TNF,GM CSF 