Going back to the origins of this thread, here is a list from the Nikon UK site with their list on what they consider professional kit.
http://www.europe-nikon.com/home/en_GB/local_content/broad/25/1.html
Here is a link to the US version of the NPS, but I can't find the equivalent equipment list.
http://www.nikonpro.com/AboutNPS.aspx
Not all the lenses on that list are professional grade meaning sealed from dust and moisture.