I have isolated B cells from mouse spleen. Briefly, you rub the dissected spleen on a wire mesh to liberate the cells, hypotonically lyse the red blood cells and then purify B cells using magnetic beads. I can dig up a more detailed protocol if you are interested.
In our experiment we are using pickup spleen and crush betwwen two rough surface slides by adding incomplete media and keep foe some time depbrss settle down then transfer supernatent in other 15 falcon tube and spun its.
Now you get a pellets of white and red cells now you needed RBCs lysis which done by using 10X PBS in 100ul in disspersed pellets and after 10sec. add 900ul of triple disstiled water now againg added 5ml media and spun its this steps repeat till you get pellets of white cells now finally cells dispersed in RPMI complete media with 10% FBS or FCS and 1X antimycotic and antibiotic in complete media and plate its according to their experiment in culture plate.
I thinks this way you able to minimising cells death.