The 29-year-old actress shared a photograph of herself wearing nothing but a black bra and a necklace on
Instagram afterwards, with the caption: "The @plannedparenthood event in LA tonight was so crazy inspiring. I also spontaneously auctioned the ovary patterned sweater off my body for a nice 4k to benefit PP... Had to walk home in my skivvies and a men's coat #worthit #onbrand #standwithPP"
While Lena is very active on the picture sharing app, she recently admitted she no longer manages her own Twitter account after being targeted by bullies.
She said: "I don't look at Twitter anymore. I tweet, but I do it through someone else. I don't even know my Twitter password, which may make me seem like I'm no longer a sort of genuine community user. I really appreciate that anybody follows me at all, and so I didn't want to cut off my relationship to it completely, but it really, truly wasn't a safe space for me."