The current invention is directed to a method for obtaining a nucleic acid encoding an immunoglobulin variable domain from a single cell comprising the following steps: —performing a first polymerase chain reaction with three to six 5′-primer and one 3′-primer, performing with the product of the first polymerase chain reaction a second polymerase chain reaction with thirteen to sixteen 5′-primer and one 3′-primer, whereby the distance of the binding locations of the primer employed in the second polymerase chain reaction is reduced compared to the first polymerase chain reaction.