Effects of long-term, low-dose growth hormone therapy on immune function and life expectancy of mice.

We have studied effects of long-term, low-dose growth hormone therapy on the immune function and life expectancy of Balb/c mice. Sixty male Balb/c mice were aged up to the time when they started showing signs of senescence and causal death (deaths started when they became 17 months old). The aged mice were divided into two groups of 26 mice each. One group received growth hormone (30 micrograms/mouse) subcutaneously twice a week for 13 weeks. The control group received an equal volume of saline for the same period. During this treatment period, 16 control mice died (61%) whereas only 2 of the hormone-treated mice died (7%). Four mice from each group were killed and immunological functions of splenocytes were evaluated. Hormone-treated mice had higher stimulation indices for pokeweed mitogen but not for Concanavalin-A. Total IgG production was decreased but IL-1, IL-2 and TNF production was increased. After a lag period of 4 weeks, growth hormone therapy was continued for another 6 weeks. One of the growth hormone treated mice died while the control group no longer existed. Splenocyte functions of the growth hormone treated mice were compared to those of young mice. The results showed no significant difference between cytokine production (IL-1, IL-2, TNF and IgG) in the young and the hormone treated groups. Stimulation induced by concanavalin-A and pokeweed mitogen however, was higher in the young group than the old group. The mortality curve obtained suggests that long-term low-dose growth hormone treatment prolongs life expectancy.

Detection of somatotropin receptors on human monocytes.

The expression of somatotropin receptors on human peripheral blood monocytes was investigated. Binding of [125I]somatotropin to human monocytes was found to be specific and saturable. The binding was rapid and time-dependent, and was abolished by pretreatment of monocytes with trypsin. Scatchard plot analysis revealed that each cell bore more than 8 x 10(3) binding sites with an affinity constant of 1 x 10(8) M-1.

Effects of stress on the immune system.

Stress, distress and a variety of psychiatric illnesses, notably the affective disorders, are increasingly reported to be associated with immunosuppression. The concept that psychic distress may predispose to medical illness is centuries old but has only recently attracted the attention of the scientific community at large. Interdisciplinary collaboration has established psychoneuroimmunology, or neuroimmunomodulation, as a new field of investigation with the goal of rigorous scientific research into the elusive mind-body connection. This has resulted in the rapid accumulation of information which falls across the boundary lines of psychiatry, immunology, neurosciences and endocrinology. Here David Khansari, Anthony Murgo and Robert Faith review the effects of stress on the endocrine and central nervous systems and the interactions between these systems and the immune response after exposure to stress signals.

Protection of mice against Brucella abortus by immunization with polyclonal anti-idiotype antibodies.

Polyclonal goat anti-idiotypic antibodies containing internal images which mimic Brucella abortus antigens were generated from rabbit polyclonal idiotypes specific for partially purified extract of B. abortus (PX III). The anti-idiotypic antibodies were purified using two-step immunoaffinity column chromatography. The presence of internal images was demonstrated by competitive inhibition analysis using an enzyme-linked immunosorbent assay. Several groups of BALB/c mice were vaccinated with the anti-idiotypic antibodies. The vaccinated mice showed a high serum titer of antibodies specific for B. abortus. When the vaccinated mice were challenged with a virulent B. abortus strain 2308, greater than 90% reduction of bacteria in the spleen as compared to the unvaccinated control groups was seen. Immunoblotting experiments using antiserum from vaccinated mice demonstrate the ability to distinguish vaccinated mice from B. abortus infected mice. Our data indicate that the anti-idiotypic antibody containing internal images of B. abortus may be used as a vaccine and the induced antibody can be distinguished by immunoblotting from antibodies generated by natural infection with B. abortus.