For immune cells like T and B cells that means having the right ligand or surface molecule to get through the blood brain barrier, this is kind of like having the a VIP pass to get into an exclusive club.
The next piece of advice that I have for you is instead of engaging in small talk with a bunch of people, find someone that you connect with or that you vibe with and start a deep talk with them.
Venus, still retrograde, makes a conjunction with the Moon's north node on April 1st at 1.39 a.m. Pacific Time, and retrograde Mercury also makes a conjunction with the north node on April 3rd at 11.53 p.m. Pacific Time.
So this, coming the day after that conjunction of the Sun and Venus, is reinforcing a message, which has to do with accepting yourself exactly the way you are.