Human blood consists of leukocytes, thrombocytes and erythrocytes. Only leukocytes contain a cell nucleus. Thrombocytes and erythrocytes do not contain a cell nucleus. Thus, leukocytes are the most important element when estimating the amount of DNA in human blood.
The blood of a healthy individual usually contains 425 – 750 leucocyte cells per milliliter of blood. This means that the DNA content can vary between 30 – 40 µg/mL of blood depending on the donor.
Please note that the number of leukocytes per millilitre of blood can vary considerably from 225 during immunosuppression, to 4,250 during inflammation and up to 55,000 during leukemia.
The standard mass formula for dsDNA is:
mass of dsDNA (g) = moles of dsDNA (mol) x ( (length of dsDNA (bp) x 617.96 g/mol/bp) + 36.04 g/mol)
- mass of dsDNA = moles dsDNA (mol) x molecular weight of dsDNA
- molecular weight of dsDNA = (number of base pairs of dsDNA x average molecular weight of a base pair) + 36.04 g/mol
- average molecular weight of a base pair = 617.96 g/mol, excluding the water molecule removed during polymerization
- the 36.04 g/mol accounts for the 2 -OH and 2 -H added back to the ends
- bases are assumed to be unmodified