platelet contamination - (Feb/12/2002 )

dear all,
trying to look at PBMC proliferation microscopically (after separation using ficoll) i seem to fine very miniature cells though not bacteria in origin thus thinking it might be platelets. Can this be very true or is they a possible explanation to this occurence.
Thanks.

Dear Boris, I was trying to purify rat peripheral blood monocytes and get rid of RBC and granulocytes by centifugation over Nycoprep density medium. I saw exactly same thing and my boss said that the density step did not get rid of platelets although I had thought they would be removed as they are small and dense- but apparently not. I was using an adherence step to stick down monocytes and with thorough washing lymphocytes and most platelets were removed but as you are looking at total PBMC you may have to find other ways of removing them, if it is possible.

I usually remove platelets during the last wash of the PBMC by centrifuging at 200 g for 7 mins.  This pellets the leukocytes while leaving most of the platelets in suspension.  You can repeat this step if necessary.