I have for years called time of plating T0 and changed media at T4. I also do not like to draw of all of the media but rather draw off and renew 2/3 or 3/5 of total volume to avoid overwhelming cytokine shock, from the serum in the media. I also adjust any cytokines or drugs based on the final combined volume.
Thanks. You meant plating PBMCs on day 0 then change the medium on day4, correct? If so, I assume that day 5 will be Ok. Due to I work on 96-well plate, prefer no change until day 5. Thank you very much for the timely response.