Chromosome analysis from blood

For the cell culture, either peripheral blood is
used directly or lymphocytes are isolated from
peripheral blood (T lymphocytes). A sample of
about 2ml of peripheral blood is needed. The
blood is prevented from clotting by use of a heparinized
syringe, since clumping of the blood
cells precludes culturing (the proportion of heparin
to blood is about 1: 20). Peripheral blood
or isolated lymphocytes are placed in a vessel
with culture medium. The cells are generally
stimulated with phytohemagglutinin, a protein
from plants that unspecifically stimulates
lymphocytes to divide. The culture requires
about 72 hours at 37!C for cells to divide.
Lymphocyte cultures are suspension cultures;
i. e., the cells divide in culture medium without
attaching to the culture vessel. Cell division is
arrested and the culture is terminated by
adding a suitable concentration of a colchicine
derivative (colcemid) two hours prior to
harvest. Colcemid interrupts mitosis during
metaphase, so that a relative enrichment of
cells in metaphase results.