You can import these contacts, they are mainly LIONs’ (Linked In Open Networkers).
1. Log into LinkedIn.com
2. Select Contacts > Add Connections from the menu.
3. Towards the bottom of the page you will see “Import your desktop email contacts” – select this.
4. Upload each CSV.
5. Make sure all contacts are selected, then click “Invite selected contacts”.
You will need to repeat this for each CSV file, and you may run out of invites if your account is new. You will have to come back every week or so and try again until you’ve imported/invited all of the contacts.