Beta-endorphin effects on membrane transduction in human lymphocytes

Involvement of granzyme B expression in the enhancement of natural killer activity by beta-endorphin

Beta-Endorphin has been reported to enhance natural killer (NK) activity in vitro. However, few studies have examined the precise regulation of the cytolytic stage of NK cells. We therefore investigated the regulation by beta-endorphin of cytotoxicity-associated molecules such as granzyme B, perforin, and Fas ligand (FasL) in human CD16(+) NK cells. On semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) assay, the granzyme B mRNA level apparently increased in CD16(+) NK cells from high responding subjects having ratios >1.5 for the LU(30) ratio. An increase in intracellular granzyme B molecules was also detected in CD16(+) NK cells by flow cytometry. On the other hand, perforin and FasL appeared not to be involved in regulation by beta-endorphin. These findings suggest that up-regulation of granzyme B expression may be involved in the enhancement of NK activity by beta-endorphin.

Influence of beta-endorphin on the production of reactive oxygen and nitrogen intermediates by rabbit alveolar macrophages

1. Alveolar rabbit macrophages were studied for superoxide and nitric oxide production at basal levels and upon stimulation with phorbol myristate acetate (PMA), zymosan, cytokines (two types of interferon), and lipopolysaccharide in the presence (or absence) of beta-endorphin or hydroxylamine or both. 2. Beta-endorphin diminished (statistically significant at concentration of 10(-8) M) superoxide production by PMA-stimulated macrophages but augmented reactive oxygen generation (10(-12) M beta-endorphin) by zymosan-activated cells. 3. In the presence of hydroxylamine, beta-endorphin had a visible (albeit not statistically significant) suppressive effect on nitrite production by PMA-activated cells. 4. Cytokine-stimulated macrophages enhanced nitric oxide production in the presence of hydroxylamine and beta-endorphin in culture supernatants. 5. Beta-endorphin exerted different modulatory effects on the production of reactive oxygen and nitrite intermediates by rabbit alveolar macrophages (suppression or enhancement) that was strictly dependent on the method of cell activation.

beta-Endorphin enhances polyamine transport in human lymphocytes

Opioid peptides, such as beta-endorphin (beta-end), are capable of modulating in vitro proliferative response of lymphocytes. We attempted to determine the role of extracellular polyamines in the regulation of immune responses to opioid peptides by measuring the extent of polyamine uptake as adaptional response to cell activation. beta-end dose-dependently enhanced the incorporation of radioactive spermidine and spermine. When the cells were depleted of spermidine, with addition of specific inhibitors of both biosynthesis and interconversion pathway, a large increase in the incorporation of radioactive spermidine was observed. This effect appeares to be specific for beta-end, although a non-opiate-specific receptor could be involved, since beta-end-enhanced incorporation of radioactive spermidine is not blocked by naloxone. We conclude that the enhancement of polyamine incorporation may be considered as an integral component of lymphocyte activation by beta-end.

Cocaine blunts human CD4+ cell activation

Cocaine is reported to be immunotoxic. The biochemical mechanisms responsible for the immunopharmacological outcomes of cocaine in vivo and in vitro remain, however, to be fully elucidated. Our experimental data confirm that exposure of normal human T cells to micromolar concentrations of cocaine modulates T-cell responses to stimulation by a variety of stimuli, and indicate that cocaine impairs early activation events during CD4+ but not CD4- T-cell stimulation. Pre-incubation of enriched CD4+ T-cell subpopulations that express the homing receptor CD62L with nanomolar concentrations of the endogenous opioid peptide beta-endorphin leads to a more severe impairment of activation than that noted following pre-incubation with micromolar concentrations of cocaine alone. These findings begin to elucidate the molecular and cellular mechanisms of the immunopathology of cocaine. Our data support the proposition that cocaine abuse may place cocaine-abuser HIV-seropositive individuals at increased risk of opportunistic infections.

Immunology of the testicular excurrent ducts

The sperm autoantigen concentration in the epididymis equals or exceeds that in the testis. This makes the epididymis a probable site of initiation of an antisperm autoimmune response. The mechanisms regulating antisperm antibody formation in the testicular excurrent ducts and some related aspects with clinical interest are reviewed.