The Twitter maximum Follow limits are:

1,000 follows/day
2,000 follows total as long you are under the first 2000 – You can follow 2,000 people without any restriction other than the 1,000/day.

After that, your followers have to equal at least 90% of the number of people you want to follow. So if you’re following people without being followed back you’ll hit the limits.

1,000 Tweet updates/day – That’s a amazing amount  of tweeting!

100 API calls/hours – you’ll see this clients like tweetdeck or socialise — every time they refresh they’re using Api calls

If you account is spamy Twitter disable the account even when you follow no one. As long you interact all is fine. Additional Twitter watch for automated follower and massive unfollows that will caunt as spam and could disable your account