Dear Anissa,

The presence of fetal lymphocytes in the maternal circulation was first described in 1969 by Walknowska and his colleagues.  These investigators demonstrated the presence of a Y chromosome in mitogen-stimulated lymphocytes obtained from pregnant women carrying a male fetus.

Another breakthrough was the isolation of fetal lymphocytes by Fluorescence-activated cell sorting (FACS) using a monoclonal antibody against the human leukocyte antigen HLA-A2, which normally is only expressed on fetal lymphocytes and not on maternal cells. Therefore for Isolation strategy, Fluorescence activated cell sorting (FACS) is the best methods or you can use Density gradient centrifugation.

Also, In identifying the fetal cell, yield is very important because the number of fetal cells in maternal blood is very low and loss of fetal cells should be avoided. Purity will be determined by the relative number of fetal and maternal cells remaining after enrichment. A relative increase in the absolute number of fetal cells after enrichment allows the reduction of the amount of maternal background cells, and thereby, fetal cell identification by Fluorescence in situ hybridization (FISH) or polymerase chain reaction (PCR) analysis.

Dear Anissa,

Perhaps the following links will help to you:

http://www.mdpi.com/2077-0383/3/3/972/htm

http://neoreviews.aappublications.org/content/9/8/e332

http://www.clinchem.org/content/61/1/32.full

Thank you Emilija and Abdulkarim