Chronic immune stimulation by sperm alloantigens. Support for the hypothesis that spermatozoa induce immune dysregulation in homosexual males

The Biology and Evolution of HIV

▪ Abstract  This review examines the current state of knowledge about HIV/AIDS in terms of its origins, pathogenesis, genetic variation, and evolutionary biology. The HIV virus damages the host's immune system, resulting in AIDS, which is characterized by immunodeficiency, opportunistic infections, neoplasms, and neurological problems. HIV is a complex retrovirus with a high mutation rate. This mutation rate allows the virus to evade host immune responses, and evidence indicates that selection favors more virulent strains with rapid replication. While a number of controversial theories attempt to explain the origin of HIV/AIDS, phylogenetic evidence suggests a zoonotic transmission of HIV to humans and implicates the chimpanzee (Pan troglodytes troglodytes) as the source of HIV-1 infection and the sooty mangabey as the source of HIV-2 infection in human populations. New therapies provide hope for increased longevity among people living with AIDS, but the biology of HIV presents significant obstacles to finding a cure and/or vaccine. HIV continues to be a threat to the global population because of its fast mutation rate, recombinogenic effect, and its use of human defenses to replicate itself.

Anorectal diseases

A proper understanding of the disease of the anorectum in the HIV-positive population mandates a familiarity with the ongoing advances in antiviral chemotherapy, mechanisms of oncogenesis, and effect of HIV infection on wound dynamics. As the prognosis for HIV-infected patients improves, therapies must reflect the expected increased survival of these patients.

Complicated anorectal sepsis

These complex anorectal conditions are difficult to diagnose because clinical features overlap. In general, an aggressive approach is reserved for hidradenitis suppurativa and necrotizing infections. Patients with Crohn's disease, hematologic disorders, or AIDS are often treated more conservatively, but the correct timing and degree of aggressiveness of surgical intervention may considerably improve the overall outcome. The increasing incidence of AIDS and the frequency with which infected patients present to surgical clinics make it imperative that all surgeons have a working knowledge of the conditions associated with this syndrome. Expertise is required not only to diagnose and treat these conditions but also to protect oneself and others from being inadvertently infected with the HIV. A high index of suspicion and constant vigilance permit the successful resolution of many of these challenging problems.

Semen alloantigens and lymphocytotoxic antibodies in AIDS and ICL

More than 90% of people with AIDS develop circulating immune complexes (CICs) and lymphocytotoxic antibodies (LCTAs). Animals infected with HIV, however, never display CICs or LCTAs, and remain healthy. Similarly, HIV-infected people who do not develop CICs or LCTAs also do not progress to AIDS. The appearance of CICs and LCTAs is, however, highly prognostic for AIDS and death. Since HIV infection does not, per se, lead to the development of CICs and LCTAs, other causes are likely. One such cause, for which both epidemiologic and experimental evidence exists, is semen. Semen components include sperm, seminal fluid, lymphocytes, and sometimes infectious agents, including HIV, mycoplasmas, and herpes and hepatitis viruses, all of which independently cause immune suppression. Extensive evidence demonstrates sperm (and various viruses) contains many proteins mimicking the CD4 protein of T-helper cells, while HIV, mycoplasmas, and seminal fluid mimic class II MHC proteins of other lymphocytes. We identify a large number of protein sequences that display such mimicry using computer homology searching, and demonstrate experimentally that sperm antibodies specifically precipitate antibodies against class II MHC mimics such as mycoplasmas, which in turn precipitate antibodies to lymphocyte antigens. These data prove that immunologic exposure to sperm and lymphocytes (as may occur in receptive anal intercourse, needle sharing, or blood transfusions) is theoretically capable of initiating lymphocytotoxic autoimmunity. Such autoimmunity may play a significant role in the pathogenesis of AIDS, and will need to be addressed clinically in high risk individuals regardless of HIV status and regardless of the success of anti-HIV prophylaxis and treatment.

The epidemiology and transmission of AIDS: a hypothesis linking behavioural and biological determinants to time, person and place

Epidemiologically, the Acquired Immune Deficiency Syndrome, AIDS, is transmitted and distributed in the USA and Europe almost entirely in well-defined subsets of populations engaging in, or subjected to, the effects of behaviours which carry high risks of genital and systemic infections. The persons predominantly affected are those engaging in promiscuous homosexual and bisexual activity, regular use of addictive drugs, and their sexual and recreational partners. In such persons and in subsets of populations with corresponding life-styles, the risk of AIDS increases by orders of magnitude. Because of continuity of risk behaviour and of associated indicator infections, the incidence of AIDS over 3-5 year periods is predictable to within 10% of actual totals of registered cases in the USA and UK. Secondary transmission of AIDS beyond these groups is minimal or, in many locations, absent. There is no indication of appreciable spread by heterosexual transmission to the general population. The Human Immunodeficiency Virus, HIV, is transmissible to some extent in general populations, and more so among promiscuous persons. It may cause viraemia, lymphadenopathy and latent infection (HIV disease) in anyone. In persons engaging in risk behaviours which themselves alter or suppress immune responses, it can interact with MHC, antibodies to other organisms and to semen, and other allogenic antigens to initiate a programmed death of CD4 lymphocytes and other defensive cells, as in graft-host rejections. This occurs also in haemophiliacs receiving transfusions of blood products, and is more pronounced in persons with reactive HLA haplotypes. The susceptibility of particular subsets of populations to AIDS is thereby largely explained. But these changes occur in the absence of HIV, and so do Kaposi's sarcoma, lymphadenopathies and opportunistic infections which are regarded as main indicators of AIDS. The hypothesis that HIV-1 can do all this by itself and thereby cause AIDS is falsifiable on biological as well as epidemiological grounds. An alternative hypothesis is proposed, linking the incidence of AIDS to the evolution of contemporary risk behaviour in particular communities and locations in the USA, UK and probably in most of Europe. It does not pretend to explain the reported incidence of AIDS in Africa and other developing regions where data are insufficient to provide validation of the pattern of disease and contributory variables. The immediate, practical implication of this alternative hypothesis is that existing programmes for the control of AIDS are wrongly orientated, extremely wasteful of effort and expenditure, and in some respects harmful.

Lysis of CD4+ lymphocytes by non-HLA-restricted cytotoxic T lymphocytes from HIV-infected individuals

Individuals infected with HIV have elevated numbers of total and activated CD8+ lymphocytes in peripheral blood. CD8+ lymphocytes from HIV-infected individuals have been shown to mediate non-human histocompatibility-linked antigen (HLA)-restricted suppression of viral replication, HLA-restricted killing of cells expressing HIV antigens, and killing of uninfected lymphocytes. We studied CD8+ T lymphocytes that lysed autologous CD4+ lymphocytes. heterologous CD4+ lymphocytes from HIV-infected individuals and uninfected CD4+ lymphocytes. Killing in all cases required T cell receptor (TCR)-mediated recognition or triggering. However, these CD8+ cytotoxic T lymphocytes (CTL) killed HLA class I mismatched CD4+ lymphocytes and CD4+ lymphocytes treated with a MoAb against HLA-A, B and C antigens (PA2.6) which blocks HLA class I-restricted killing. HLA class II-negative CD4+ T lymphoma cells (CEM.NKR) were also killed by anti-CD3 inhibited CTL. Stimulation of peripheral blood lymphocytes (PBL) from HIV-infected individuals, but not uninfected controls, with concanavalin A (Con A) and IL-2, induced non-HLA-restricted TCR alpha beta+, CD8+ CTL which lysed CD4+ lymphocytes. Activation of CD4+ lymphocytes increased their susceptibility to CD8+ CTL-mediated lysis. In HIV infection, a population of non-HLA-restricted CTL which lyse activated CD4+ lymphocytes is expanded. The expansion of CTL with unusual characteristics is interesting, because the stimulus for this expansion is unknown. CTL which recognize activated CD4+ cells could play a role in immune regulation and the pathogenesis of AIDS.

Anti-sperm antibodies in homosexual men: prevalence and correlation with sexual behaviour

The sera of 60 homosexual males were examined for the presence of antibodies to sperm using an indirect immunobead test (IBT). Six of 60 (10%) had antibodies of IgG isotype; in addition two of the six had antibodies of IgA isotype. The presence of antibodies was associated with the practice of unprotected receptive anal intercourse in the previous six months. Antibodies were not found in homosexual men who were celibate, or who practised only oral intercourse during the same period. There was no correlation between the presence of anti-sperm antibodies and antibodies to human immunodeficiency virus (HIV), or numbers of T lymphocytes. These preliminary results lend support to the hypothesis that antigen presentation in the lower gut may be a source of sensitisation against sperm. The possibility that anti-sperm antibodies may be a marker of receptive anal intercourse merits further investigation.

Testicular atrophy in homosexual AIDS patients: an immune-mediated phenomenon?

An immunopathologic analysis of the testes of 20 homosexual acquired immune deficiency syndrome (AIDS) patients was performed to investigate the hypothesis that the testicular atrophy of these patients represents an immune-mediated process. The findings were compared to those in a control group of heterosexual men without AIDS. The testes of the homosexual AIDS patients showed an overall lower degree of spermatogenesis with more prominent interstitial inflammation and thickening of the tubular basement membrane. However, direct immunofluorescence and immunoperoxidase studies failed to demonstrate significant differences in the prevalence of immune complex deposits along the tubular basement membrane in the two study groups. No electron-dense deposits were demonstrated in cases examined ultrastructurally. Therefore, this study does not support the hypothesis that the testicular atrophy of homosexual AIDS patients is a manifestation of autoimmune orchitis. Further studies are needed to elucidate the pathogenesis of the testicular atrophy in AIDS, as this appears to be a specific manifestation of the disease.

Does exposure to HLA alloantigens trigger immunoregulatory mechanisms operative in both pregnancy and AIDS?

The complex biological processes responsible for regulating the immune system are presently the subject of considerable interest and study. New insight into this process comes from a variety of observations and it is the purpose of this communication to develop the hypothesis that two seemingly quite disparate observations point to a common biological mechanism bearing on immunoregulation. The observations concern the unique immunologic relationship between mother and fetus and the immunoregulatory abnormalities encountered in HIV-induced acquired immunodeficiency syndrome (AIDS). Exposure to foreign (allo) major histocompatibility complex (MHC) antigens can potentially occur during pregnancy, the transfusion of blood or blood products, or anal insemination. The hypothesis, in its simplest form, states that such MHC alloantigenic exposure triggers a sequence of immunoregulatory mechanisms resulting in immunosuppression and that this response has evolved in placental mammals as a means of protecting the fetus from maternal immune rejection and promoting optimal fetal development.

Idiopathic production of interleukin-1 in acquired immune deficiency syndrome

We determined the capacity of peripheral blood monocytes from 19 patients with acquired immune deficiency syndrome (AIDS) or related conditions (1 with lymphadenopathy, 8 with AIDS-related complex, and 10 with AIDS) to produce intracellular and extracellular interleukin-1 (IL-1) spontaneously and upon stimulation with bacterial endotoxin. All patients were anti-human T-cell lymphotropic virus type III antibody positive. Results were compared with those obtained with 10 normal controls of similar age. A subset of patients who spontaneously produced high amounts of intracellular and extracellular IL-1 was identified. Total production of IL-1 in this subset was an average of 2.9 times that of controls. It is suggested that spontaneous production of IL-1 in this group represents an in vivo phenomenon since it was associated with more than 3 g of globulins per deciliter of serum, more than 2,300 mg of immunoglobulins per deciliter of serum, higher IgA values, higher titers of anti-Epstein-Barr virus antibodies, and lower neutrophil counts in peripheral blood. The role of Epstein-Barr virus, human immunodeficiency virus itself, or other infectious agents in spontaneous IL-1 production by these patients remains to be determined. Stimulation with endotoxin induced intracellular and extracellular IL-1 production to similar levels in patients and controls. These results show that AIDS patients are able to produce and release IL-1. High idiopathic production of IL-1 identified in some patients can help to explain the hypergammaglobulinemia seen in AIDS patients and might also be related to progression and severity of the disease.

Histopathology of testis in acquired immune deficiency syndrome

Histologic sections from the testes of 32 autopsied patients with acquired immune deficiency syndrome (AIDS) were examined. Almost invariably the testes displayed decreased spermatogenesis, and 20 of the 32 cases showed marked hypospermatogenesis with Sertoli cells predominantly lining the tubules. Although the seminiferous tubules were generally of normal size, the tunica propria at the periphery of the tubules was mildly to moderately thickened in 19 cases and markedly thickened in 10. The interstitial cells of Leydig were unaltered in most patients, with only 4 testes showing Leydig cell hyperplasia. The testicular blood vessels were slightly thickened in many patients, but 5 exhibited moderate to marked intimal proliferation with narrowing of the lumen. Mononuclear inflammatory infiltration of the testicular interstitium was slight in 11 cases, moderate in 6. Only 7 of the 28 AIDS patients with opportunistic infections had evidence of direct involvement of the testes by the infectious organisms. We concluded that the extragonadal endocrine balance of AIDS patients may be deranged due to the infectious process and so deserves clinical evaluation.

Sexual lifestyle and clinical findings related to HTLV-III/LAV status in homosexual men

A study of 304 sexually active homosexual men, most of whom had multiple casual partners, showed that receptive anogenital intercourse, independent of anal bleeding, was the only risk factor for HTLV-III/LAV transmission. There was no evidence that HTLV-III/LAV infection, measured by seropositivity, was transmitted by oroanal or orogenital routes, or that insertive penile intercourse constituted a risk. The strongest predictor of seropositivity proved to be homosexual activity for more than five years, which may lead to enhanced susceptibility to infection. Sexual exposure to European men seemed to be even more hazardous than sexual exposure to men from the United States of America, and emphasised the epidemiological importance of the promiscuous homosexual abroad. Skin complaints were the most common presenting symptoms in men with antibody to HTLV-III/LAV. Extrainguinal lymphadenopathy was the commonest sign, which was present in just under half of those who were seropositive. More than one quarter of seropositive patients had had sexual intercourse with a woman in the five years before being tested.

Prostaglandin E2 administered via anus causes immunosuppression in male but not female rats: a possible pathogenesis of acquired immune deficiency syndrome in homosexual males

To explain a possible pathogenesis of acquired immune deficiency syndrome (AIDS) in homosexual males, we propose the following hypothesis. Prostaglandin E2 in human semen given via anus during anal intercourse may cause an immune dysregulation in the male semen recipients; this immunosuppressive effect of prostaglandin E2 may be one of the underlying factors that stimulate AIDS-associated virus infection or that trigger the latent AIDS-associated virus. This hypothesis is supported by the following experimental results. Anal infusion of prostaglandin E2 or D2 into male rats reduced in vitro responses of T lymphocytes to phytohemagglutinin. However, the T-cell response of female rats was not reduced significantly by the anal infusion of seminal prostaglandins.

Long term follow up of chronic hepatitis B virus infection in intravenous drug abusers and homosexual men

Long term follow up of 16 homosexual men and 78 intravenous drug abusers who were chronic carriers of hepatitis B surface antigen (HBsAg) showed fundamental differences between the two groups. Viral replication, expressed by the presence of hepatitis B e antigen, lasted for four years or more in 10 out of 14 (71%) of the homosexual men whereas it was not present in 43 out of 73 (59%) of the drug addicts within one year. This shows a difference in the immunological response between homosexual HBsAg carriers and addicts that is not related to infection with human T cell lymphotropic virus type III. Severe histological damage such as chronic aggressive hepatitis, cirrhosis, or primary liver cancer was found in more than half of the homosexual men who underwent biopsy examinations. In drug addicts chronic persistent hepatitis was a regular finding in the absence of markers of delta infection, but in those addicts infected with the delta agent the degree of liver damage was comparable with that found in homosexual men.

Unregulated production of virus and/or sperm specific anti-idiotypic antibodies as a cause of AIDS

A network of idiotypic and anti-idiotypic antibodies is often suggested as the basis for cellular interactions that maintain a steady-state immunological equilibrium. This hypothesis proposes that repeated exposure to certain external antigens--ie, both viral and sperm--stimulates an unregulated production of a uniquely potent immunomodulating idiotypic antibody(ies). In a genetically predisposed individual, this particular antibody(ies), which is also an autoantibody(ies), results in a cellular immune deficiency. This disruption in the immune system permits opportunistic infection and thus the acquired immune deficiency syndrome. This hypothesis, which is readily testable and which does not involve a primary pathogen, can explain both the active induction of this disease in, as well as its passive transfer to, all at-risk populations.

Depression of murine natural killer cell cytotoxicity by isobutyl nitrite

We have investigated the effect of isobutyl nitrite on murine NK-cell antitumor-directed cytotoxicity. This agent has been suggested as one of the factors underlying immunodeficiency syndrome (AIDS) in man. We demonstrated that two injections, each of 0.25 ml isobutyl nitrite, resulted in significant depression of endogenous splenic and peripheral blood natural killer (NK) cell cytotoxicity against T-cell lymphoma, YAC-1. In addition to endogenous NK cells, activity of pyrimidinol-activated NK cells was also substantially depressed by this agent. The latter observation is of the utmost importance, since it suggests that the attempt to augment NK-cell activity (to promote resistance to infections and malignancies) could fail in patients with AIDS who are isobutyl nitrite users. Isobutyl nitrite was NK-cell-suppressive not only after in vivo administration but, most importantly, also after inhalation. This indicates that isobutyl nitrite, via its NK-cell suppressive effect, could contribute to immunodeficiency in AIDS. Studies on the mechanism of NK-cell depression by isobutyl nitrite demonstrated that the NK-cell tumor-binding properties as well as NK-cell cytotoxic potential were substantially depressed. Mixing experiments failed to reveal any regulation by suppressor cell activities. The results of these studies clearly indicate that isobutyl nitrite is an immunosuppressive agent and that its use should be avoided.