<prompt> Which among the following hypersensitivity cannot be detected by skin testType 1type 2Type 3Type 4  <response>: Ans b: Ref: ROBBINS 7th edition-210Type 1: Immediate hypersensitivity- Involves Ig E mediated release of histamine other mediators from mast cells basophilsEg: Skin tests-Casonis testType 2: Antibody mediated - Involves IgG or IgM with subsequent complement fixationType 3: Immune compex mediated- Involve circulating Ag-Ab complex that deposit in venules with subsequent complement fixation systemic- serum sickness -skin, joint, lungs, kidney, blood vessels localized - arthus reaction - skinType 4: Delayed hypersensitivity-mediated by T cells Eg: Tuberculin tests, Lepromin testsExamples of types of reationare given in previous, please go through it 