In immediate hypersensitivity, the initial exposure to an allergen usually does not produce any symptoms. the symptoms, such as those involved in anaphylaxis, usually appear in the second exposure. what events are occurring during this initial exposure that sensitizes a person to an allergen? in your description include the role of b cells, t cells, ige, mast cells, basophils and the allergen.

During the initial exposure to the allergen, contact is made with B cells, these B cells differentiate and produce IgE antibody. The IgE antibodies which works against the allergens are released into the blood stream where they binds to Fc receptors which are located on mast cells and basophils. Now, the mast cells has become sensitized and they will wait patiently for the second exposure. When contact with the allergen is made the second time, the allergen becomes attached to the IgE present on the mast cells and this result in degranulation which trigger a lot of allergic responses.