Abstract: A nucleic acid with which expression of a polypeptide having interleukin-16 activity can be achieved or regulated in a prokaryotic or eukaryotic host cell, wherein in the region coding for the polypeptide, the nucleic acid (1) corresponds to the DNA sequence SEQ ID NOS:1 and 5-7 or its complementary strand; (b) hybridizes under stringent conditions with the DNA of sequence SEQ ID NOS:1 and 5-7; (c) or is a nucleic acid sequence which, if there was no degeneracy of the genetic code, would hybridize under stringent conditions with the nucleic acid sequences defined by (a) and (b); (d) and, if it codes for a polypeptide having interleukin-16 activity, is suitable as genomic DNA for the recombinant production of IL-16 in eukaryotic host cells and processes for producing the same and pharmaceutical compositions containing the same.