Interleukin-16 is a natural chemical, or cytokine. In test-tube studies it suppresses the replication of HIV and SIV. Researchers in Germany are investigating the theory that IL-16 is found at high levels in the blood of African green monkeys which are naturally infected with SIV in the wild but have low levels of SIV in their blood and never develop simian AIDS. IL-16 is known to bind to the CD4 receptor, so one possible mode of action is that it competes with HIV, blocking the CD4 receptors and preventing the virus gp120 molecule from binding.

References

Baier M et al. HIV suppression by interleukin-16. Nature 378(6557):563, 1995.