<prompt> Type IV hypersensitivity reaction is mediated by which of following?B cellsActive T cellsNK cellsPlasma cells  <response>: Ans. b Active T cells. Ref. Textbook of Microbiology by Anantanarayan, 6thl 55HYPERSENSITIVITY REACTIONSHypersensitivity Reaction typePrototypeImmune MechanismsImmediate type IAllergiesAnaphylaxisBronchial asthmaCasonis test JK09Production of IgE antibodyAntibody mediated CYTOTOXIC type IIAutoimmune hemolytic anemia; GBSProduction of IgG, IgM absImmune complex mediated type IIIAutoimmune diseases SLE, RA, etc,Some bacterial, viral and parasitic infections e.g. PSGN, Hepatitis B, malaria, etc, Disseminated malignancies,Serum sickness, Arthus reactionNecrotizing vasculitis.Deposition of ag-ab complexes and complement activationCell-mediated type IVContact dermatitisMultiple sclerosisType-1 DM,TB,Transplant rejectionActivated T-Lymphocytes Macrophage activation T-cell mediated cytotoxicity.Type VGraves diseaseLATS 