Interleukin-16 (IL-16), produced by activated CD8+ T lymphocytes, is inhibitory to human immunodeficiency virus-1 (HIV-1) replication. In an attempt to determine whether human B cells express and secrete IL-16, a wide panel of B-cell lines derived from patients with acquired immune deficiency syndrome (AIDS)-associated B-cell lymphomas (AABCL) (n = 5) and from non-AABCLs (n = 8) were studied. Using reverse transcription-polymerase chain reaction (RT-PCR) analysis, we were able to observe ubiquitous expression of IL-16 mRNA. Kinetic studies on constitutive mRNA turnover and secretion for IL-16 suggests that the optimum expression is at 24 hr. Interestingly, we report, for the first time, IL-16 secretion by human B-cell lines.