to make someone sensitive to something

It seems very likely that air pollutants are sensitizing people so that they become allergic to pollen. 空气污染似乎很有可能使人们变得敏感，从而对花粉产生过敏反应。

to make someone familiar with something such as a problem or bad situation

The association aims to sensitize employers to the problems faced by left-handed people in the workplace. 协会意在使雇主们意识到惯用左手的员工在工作上所面临的问题。