In vertebrates the development of host protection against pathogens requires a selective host immune response that involves the mobilization of the humoral and/or cellular mediated immune responses. Several factors adversely affect the body's protective response capability by causing prolonged immuno-suppression or "down-regulation" of the immune system. It is, in reality, more appropriate to speak of "mal-regulation" or "deregulation" of the immune system than of "down-regulation" since the result is a failure to protect the body from assault. Immuno-suppression provides an opportunity for pathogens to grow in the host. It does not matter what causes the primary insult to immunity. The resulting inability to muster the appropriate immune response has the same effect. Among the many different causes of immuno-suppression are viral, bacterial, fungal, yeast and parasitic infections, chemotherapy, irradiation, severe stress, chronic fatigue syndrome, diabetes mellitus and some forms of steroid therapy.
It has long been known that patients receiving steroid hormones of adrenocortical origin at pharmacologically appropriate doses show increased incidence of infectious disease. A. S. Fauci, immunolo.rev. 65, 133-155 (1982); and J. E. Parillo and A. S. Fauci, Annual Review of Pharmacology and Toxicology 19, 179-201 (1979). Dehydroepiandrosterone, also known as 3-.beta.-hydroxyandrost-5-en-17-one or dehydroiso-androsterone (referred to hereinafter as DHEA), is a 17-ketosteroid which is quantitatively one of the major adrenocortical steroid hormones found in mammals. M. E. Windholz, The Merck Index, Ninth Edition (1976); K. Diem and C. Lentner, Geigy Scientific Tables (1975). (Although DHEA appears to serve as an intermediary in gonadal steroid synthesis, the primary physiological function of DHEA has not been fully understood. It has been known, however, that levels of this hormone begin to decline in the second decade of life, reaching 5% of the original level in the elderly.)
Clinically, DHEA has been used systemically and/or topically for treating patients suffering from psoriasis, gout, hyperlipemia, and in has been administered to post-coronary patients. W. Regelson et al., New York Academy of Sciences 518, 260-273 (1988). In mammals DHEA has been shown to have weight optimizing and anticarcinogenic effects.
DHEA has been used clinically in Europe in conjunction with estrogen as an agent to reverse menopausal symptoms and also has been used in the treatment of manic depression, schizophrenia, and Alzheimer's disease. DHEA has also been used clinically at 40 mg/kg/day in the treatment of advanced cancer and multiple sclerosis. (Regelson, supra) Mild androgenic effects, hirsutism, and increased libido were the side effects observed. These side effects can be overcome by monitoring the dose and/or by using analogues.
U.S. Pat. No. 5,077,284 entitled "Use of Dehydroepiandrosterone to Improve Immune Response" describes the subcutaneous or oral administration of DHEA to improve the host's response to infections. U.S. Pat. No. 4,978,532 describes use of patch technology to deliver DHEA.
It is now disclosed that DHEA is a precursor in a metabolic pathway which ultimately leads to more powerful agents that increase immune response in mammals. That is, DHEA acts as a biphasic compound: it acts as an immuno-modulator when converted to androstenediol (5-androstene, 3.beta.,17.beta. diol hereinafter referred to as .beta.AED) or androstenetriol (5 androstene 3.beta.,7.beta.,17.beta. triol hereinafter referred to as .beta.AET), but in vitro has a certain lymphotoxic and suppressive effect on cell proliferation prior to its conversion to .beta.AED and/or .beta.AET. It is, therefore, now understood that administration of DHEA shows superior immunity enhancing properties as a result of its partial conversion to a more active metabolite.
An agent that would advance the protective regulation of the immune system without giving rise to undesirable side effects seen with DHEA administration would provide particularly advantageous improvement of host resistance against infection. Protective regulation of the immune system could then be effected using lower doses of the chemotherapeutic agent, and would provide more immediate response with a wider range of protection.