Below is the patch that added the Old hunters DLC, it notes what was added to the base game (without purchase of the DLC) everything else from the DLC requires you to purchase the DLC and enter the DLC areas.
Patch v1.07
Patch 1.07 for Bloodborne. It was released on November 20th.
Patch Notes
•New Covenant : The League
This is the confederate covenant of hunters associated with The League. You may meet Valtr (ヴァルトール) and join The League at the Forbidden Woods, in the hut that must be unlocked as a shortcut next to the first lamp. If you co-op while using the covenant rune Impurity and succeed in your task you will receive a Vermin item that will be allow you to participate in the ranking system.
•New Items: The Old Hunter Bell, Madaras Whistle (Hunter tool), One-Eyed Iron Helm and Master's Iron Helm
•New NPC Co-op Partners - please see Old Hunters page for a list of available summons.
Hunters of The League faction will be able to summon new Old Hunters into their game in several areas, including Chalice Dungeons. You must acquire the Old Hunter Bell at the Hunter's Dream and ring it to summon the Old Hunters at their specific markers. The Old Hunter Bell consumes insight on use, and you can only have a maximum of two NPC phantoms with you at a time. If you have another co-op player in your world, you can only summon one NPC helper.
•Chalice Dungeon Changes
Non-root Chalice Dungeons will now have have a default glyph in order to allow easier co-op and pvp: This means you now can find other players in the default dungeons, but if you would like to opt out you may create a unique glyph.
•Non-root Chalice Dungeons now have NPC summons in them.
•New Co-op "signs"
When using a summoning bell, you will now see phantoms of other players who are searching for co-op, and you will be see ripples under the phantoms who are looking for a multiplayer session if they are within your summoning range.
Other Changes:
•Matchmaking and Stability Improvements (unspecified)
•Chikage now has a new blood-trail effect when attacking in the two handed stance.
•All ritual materials are now purchasable at the Hunter's Dream (NG+ only)
•Augur of Ebrietas can now be used to parry/backstab. Its damage has also been increased.
•The Blood Vial used in the healing animation has been made much larger and more noticeable in your characters' hand. The same change has also been made to the "Emergency Quicksilver Bullet replenishment" animation.
•The Blood Moon in Hunter's Dream under a certain condition is now displayed correctly.
•More mist and fog effects are present in some areas. (needs confirmation)