Reduction of serum melatonin levels in HIV-1-infected individuals' parallel disease progression: correlation with serum interleukin-12 levels.

Background: During the natural history of human
immunodeficiency virus type I (HIV-1) infection, an
impairment of interleukin-12 (IL-12) production precedes a
switch from a T-helper 1 (Th1) to a T-helper 2 (Th2) stage of
cellular immunity. Melatonin, the main hormone produced by
the pineal gland, seems to promote a Th1 response by
increasing the production of IL-12 in vitro. The aim of this
study was to measure and correlate serum levels of melatonin
and IL-12 in a cohort of HIV-1-infected individuals.
Patients and Methods: 77 anti-HIV-1-positive subjects were
enrolled: 20 were in CDC stage A, 25 in CDC stage B and 32
in CDC stage C. 30 healthy HIV-1-seronegative subjects were
recruited as controls. IL-12 and melatonin concentrations
were quantitated in serum samples.
Results: Mean levels of serum melatonin were significantly
lower in HIV-1-infected individuals in comparison with
controls (p < 0.001). Within the HIV-1-seropositive group,
mean melatonin and IL-12 concentrations were significantly
lower in patients in CDC stage C, as compared with patients
in CDC stages B and A (p < 0.01).
Conclusion: During the natural history of HIV-1 disease,
serum melatonin levels are progressively reduced. This
reduction may be related to the impairment of Th1
immunoresponses.