Allergies are the result of a hypersensitive immune system. The allergic immune system misidentifies an otherwise innocuous substance as harmful, and then attacks the substance with a ferocity far greater than required.
Laying off an employee is different from firing an employee. Firing means letting a worker go for any reason, whereas a layoff refers to an employment termination based on economics, usually involving more than one worker.
A layoff is similar to a discharge, except that layoffs are not performed due to the negative behavior or poor performance of employees. Companies lay off workers when they cannot afford to pay them anymore due to financial hardship.