Engraftment of DLA-haploidentical marrow with ex vivo expanded, retrovirally transduced cytotoxic T lymphocytes.

Genetically modified donor T cells with an inducible "suicide" gene have the potential to improve the safety and availability of allogeneic hematopoietic stem cell transplantation by enhancing engraftment and permitting control of graft-versus-host disease (GVHD). However, several clinical studies of gene-modified T cells have shown limited to no in vivo function of the ex vivo expanded T cells. Using the well-established dog model of allogeneic marrow transplantation, the question was asked if retrovirally transduced, donor derived, ex vivo expanded cytotoxic T lymphocytes (CTLs) that are recipient specific could enhance engraftment of dog leukocyte antigen (DLA)-haploidentical marrow following a single dose of 9.2 Gy total body irradiation and no postgrafting immunosuppression. In this setting, only 4 of 11 control recipients of DLA-haploidentical marrow without added CTLs engrafted. CTLs did not enhance engraftment of CD34(+) selected peripheral blood stem cells. However, recipient-specific CTLs enhanced engraftment of DLA-haploidentical marrow in 9 of 11 evaluable recipients (P =.049). All dogs that engrafted developed multiorgan GVHD. To facilitate in vivo tracking, 8 dogs received CTLs transduced with a retroviral vector encoding green fluorescent protein (GFP) and neomycin phosphotransferase (neo). Recipients that engrafted had sharp increases in the numbers of circulating GFP(+) CTLs on days +5 to +6 after transplantation. GFP(+) CTLs isolated from blood were capable of recipient-specific lysis. At necropsy, up to 7.1% of CD3(+) cells in tissues were GFP(+) and polymerase chain reaction in situ hybridization for neo showed infiltration of transduced CTLs in GVHD-affected organs. These results show that ex vivo expanded, transduced T cells maintained in vivo function and enhanced marrow engraftment.

Treatment of primary human immunodeficiency virus type 1 infection with potent antiretroviral therapy reduces frequency of rapid progression to AIDS.

Immunologic data supporting immediate antiretroviral therapy in primary human immunodeficiency virus type 1 (HIV-1) infection are emerging; however, clinical benefit has not been demonstrated. The clinical and virologic course of 47 patients who were enrolled from September 1993 through June 1996 and who were not initially treated with potent therapy was compared with the course of 20 patients who immediately began therapy with zidovudine, lamivudine, and indinavir. Demographic and baseline laboratory data were comparable. During 78 weeks of follow-up, the early-treatment cohort showed a reduced frequency of opportunistic infections (5% vs. 21.3%; relative risk, 0.11; P=.02), less frequent progression to AIDS (13% vs. 0%), and significantly less frequent nonopportunistic mucocutaneous disorders and respiratory infections (P<.01). Plasma HIV-1 RNA levels were <50 copies/mL in all patients who continued therapy; however, after 9--12 months, HIV-1 remained detectable in latently infected CD4(+) T cells and in lymph node mononuclear cells. Combination antiretroviral therapy during primary HIV-1 infection demonstrated a decreased frequency of minor opportunistic infections, mucocutaneous disorders, and respiratory infections and reduced progression to AIDS.

Ovine lentivirus is aetiologically associated with chronic respiratory disease of sheep on the Laikipia Plateau in Kenya.

A study was undertaken to investigate the occurrence of ovine lentivirus (OvLV) infection in sheep with chronic respiratory disease on the Laikipia Plateau, Kenya. All seven Merino crossbred sheep with chronic dyspnoea and emaciation examined for gross and microscopic lesions had lymphoid interstitial pneumonia (LIP), and one also had pulmonary abscesses. Two of the sheep with LIP also had lesions of ovine pulmonary carcinoma (OPC, jaagsiekte). Using in situ hybridization, OvLV DNA localized to a high proportion of pulmonary macrophages in lungs with lesions of LIP. Lung tissue samples from six of these sheep were positive for a syncytium-inducing virus in cultures of lamb testis cells. Thin-section electron microscopy of infected cells showed virions with morphogenesis typical of lentiviruses. In a western blotting assay, monoclonal antibodies to the OvLV capsid (CA, p27) and matrix (MA, p15) proteins of a North American OvLV isolate reacted with similar-sized bands of the virus, and serum from six of the sheep were reactive with CA from the Kenyan viral isolate. Using an OvLV agar gel immunodiffusion (AGID) test, all seven sheep were positive for serum antiviral antibody, as were 29% of 63 clinically normal sheep from Laikipia District. However, when sera from the healthy sheep were tested in a western blot assay, only 52% had IgG reactive to the OvLV CA, indicating a high rate of false negative reactions with the AGID test. Serum samples from 87 Red Maasai or Dorper crossbred sheep from two farms in other parts of Kenya were OvLV seronegative by both the AGID test and the western blot assay. These results document the first identification of OvLV as a cause of chronic respiratory disease in sheep in Kenya and show a high rate of infection in sheep flocks, with a high prevalence of chronic respiratory disease.

Mucosal shedding of human herpesvirus 8 in men.

BACKGROUND: Epidemiologic studies suggest that human herpesvirus 8 (HHV-8) is sexually transmitted among men who have sex with men; however, the mode of transmission is unclear. METHODS: To evaluate the patterns of shedding of HHV-8, we obtained mucosal-secretion samples from a cohort of HHV-8-seropositive men who had sex with men and had no clinical evidence of Kaposi's sarcoma. Quantitative polymerase-chain-reaction (PCR) assays, in situ PCR assays, and in situ RNA hybridization were used to identify potential sources of infectious HHV-8. RESULTS: We detected HHV-8 in at least one mucosal sample from 30 of 50 men who were seropositive for HHV-8 (60 percent). Overall, HHV-8 was detected in 30 percent of oropharyngeal samples, as compared with 1 percent of anal and genital samples (P<0.001). In 39 percent of the HHV-8-seropositive men, HHV-8 was detected in saliva on more than 35 percent of the consecutive days on which samples were obtained. The median log titer of HHV-8 from the oral cavity was approximately 2.5 times as high as the titer at all other sites. In situ hybridization studies indicated that HHV-8 DNA and messenger RNA were present in oral epithelial cells. Among 92 men who had sex with men and who were seronegative for the human immunodeficiency virus (HIV), a history of sex with a partner who had Kaposi's sarcoma, deep kissing with an HIV-positive partner, and the use of amyl nitrite capsules ("poppers") or inhaled nitrites were independent risk factors for infection with HHV-8. CONCLUSIONS: Oral exposure to infectious saliva is a potential risk factor for the acquisition of HHV-8 among men who have sex with men. Hence, currently recommended safer sex practices may not protect against HHV-8 infection.

Nonlymphoid reservoirs of HIV replication in children with chronic-progressive disease.

Autopsy tissues from 2 cohorts of age-matched HIV-infected children with similar plasma viral load (>10(5) HIV RNA copies/ml), but with distinct AIDS-associated disease manifestations, were examined for sites of persistent HIV replication. One group consisted of 3 children with severe lymphoid atrophy and peripheral blood CD4+ T cell counts of < 10/mm . Another group was composed of 6 children with extensive hyperplasia of mucosal-associated lymphoid tissues and blood CD4+ T cell counts >500/mm3. Hyperplastic bronchiole- and gut-associated lymphoid tissues were characterized by extensive networks of germinal center follicular dendritic cells (FDC) containing large amounts of immune-complexed virion RNA. Conversely, pulmonary and gastrointestinal tissues from children with severe CD4+ T cell depletion were devoid of any secondary lymphoid structures, yet these tissues also harbored high concentrations of HIV RNA. Dual in situ procedures showed that only macrophage (Mphi) within these sites contained tat fusion transcripts, a product of post-transcriptional splicing and a correlate of productive infection. When examining explant cultures of Mphi and FDC, only Mphi harbored HIV tat mRNA and only Mphi demonstrated budding retroviral particles. Hence, germinal center FDC in secondary lymphoid tissues are key reservoirs of immune-complexed HIV RNA and are likely to contribute to AIDS-associated lymphoproliferations; however, these cells do not support HIV replication, and failure to do so results from a post-transcriptional block in the virus life cycle. Moreover, gut and pulmonary Mphi represent a lineage of cells that are permissive to HIV replication and contribute significantly to the high viral load in children with severe CD4+ T cell depletion. It will be important to identify the molecular mechanisms that allow for these highly productive infections of Mphi.

HIV-specific cytotoxic T lymphocytes traffic to lymph nodes and localize at sites of HIV replication and cell death.

We have tracked the in vivo migration and have identified in vivo correlates of cytotoxic T-lymphocyte (CTL) activity in HIV-seropositive subjects infused with autologous gene-marked CD8(+) HIV-specific CTL. The number of circulating gene-marked CTL ranged from 1.6 to 3.5% shortly after infusion to less than 0.5% 2 weeks later. Gene-marked CTL were present in the lymph node at 4.5- to 11-fold excess and colocalized within parafollicular regions of the lymph node adjacent to cells expressing HIV tat fusion transcripts, a correlate of virus replication. The CTL clones expressed the CCR5 receptor and localized among HIV-infected cells expressing the ligands MIP-1alpha and MIP-1beta, CC-chemokines produced at sites of virus replication. Aggregates of apoptotic cells and cells expressing granzyme-B localized within these same sites. In contrast, lymph node sections from untreated HIV-seropositive subjects, all with significant viral burden (> 50,000 HIV RNA copies/mL plasma), showed no CC-chemokine expression and exhibited only sporadic and randomly distributed cells expressing granzymes and/or apoptotic cells. These studies show that the infused CTL specifically migrate to sites of HIV replication and retain their antigen-specific cytolytic potential. Moreover, these studies provide a methodology that will facilitate studies of both the magnitude and functional phenotype of Ag-specific CD8(+) T cells in vivo.

Pediatric AIDS-associated lymphocytic interstitial pneumonia and pulmonary arterio-occlusive disease: role of VCAM-1/VLA-4 adhesion pathway and human herpesviruses.

Because the mechanisms of lymphocyte accumulation in the lungs of children with AIDS-associated lymphocytic interstitial pneumonia (LIP) are unknown, we studied the relative contributions of known adhesion pathways in mediating lymphocyte adherence to endothelium and the potential role of human herpesviruses in the expansion of these lesions. LIP was characterized by lymphoid hyperplasia of the bronchus-associated lymphoid tissue (BALT) and infiltration of the pulmonary interstitium with CD8(+) T lymphocytes. In some individuals there was expansion of the alveolar septae with dense aggregates of B lymphocytes, many containing the Epstein-Barr viral (EBV) genome. Patients with concurrent EBV infection also demonstrated large-vessel arteriopathy characterized by thickening of the intimae with collagen and smooth muscle. Venular endothelium from the lung of children with LIP, but not uninflamed lung from other children with AIDS or lung from children with nonspecific pneumonitis, expressed high levels of vascular cell adhesion molecule-1 (VCAM-1) protein. In turn, inflammatory cells expressing very late activation antigen-4 (VLA-4), the leukocyte ligand for VCAM-1, were the predominant perivascular infiltrate associated with vessels expressing VCAM-1. Expression of other endothelial adhesion molecules, including intracellular adhesion molecule-1 and E-selectin, was not uniformly associated with LIP. Using a tissue adhesion assay combined with immunohistochemistry for VCAM-1, we show that CD8(+) T cell clones that express VLA-4 bind preferentially to pulmonary vessels in sites of LIP: vessels that expressed high levels of VCAM-1. When tissues and cells were pretreated with antibodies to VCAM-1 or VLA-4, respectively, adhesion was inhibited by >/=80%. Thus, infiltration of alveolar septae with CD8(+) T cells was highly correlative with VCAM-1/VLA-4 adhesive interactions, and focal expansion of B cells was coincidental to co-infection with EBV.

In vivo migration and function of transferred HIV-1-specific cytotoxic T cells.

The persistence of HIV replication in infected individuals may reflect an inadequate host HIV-specific CD8+ cytotoxic T lymphocyte (CTL) response. The functional activity of HIV-specific CTLs and the ability of these effector cells to migrate in vivo to sites of infection was directly assessed by expanding autologous HIV-1 Gag-specific CD8+ CTL clones in vitro and adoptively transferring these CTLs to HIV-infected individuals. The transferred CTLs retained lytic function in vivo, accumulated adjacent to HIV-infected cells in lymph nodes and transiently reduced the levels of circulating productively infected CD4+ T cells. These results provide direct evidence that HIV-specific CTLs target sites of HIV replication and mediate antiviral activity, and indicate that the development of immunotherapeutic approaches to sustain a strong CTL response to HIV may be a useful adjunct to treatment of HIV infection.

An exploration of the potential benefits of pet-facilitated therapy.

There is mounting evidence to suggest that those who keep pets are likely to benefit from various improvements in health. Despite founders of nursing such as Florence Nightingale advocating the importance of animals within the care environment, their integration into hospitals and other health care settings has been slow. The literature on animal-induced health benefits is reviewed and the conclusion is drawn that the potential benefits of pet therapy are considerable. It is suggested that nurses can assume an active role in advocating ward pet or pet-visiting schemes.

The effects of pharmacological and lentivirus-induced immune suppression on orbivirus pathogenesis: assessment of virus burden in blood monocytes and tissues by reverse transcription-in situ PCR.

We investigated the effects of pharmacological and lentivirus-induced immunosuppression on bluetongue virus (BTV) pathogenesis as a mechanism for virus persistence and induction of clinical disease. Immunologically normal and immunosuppressed sheep were infected subcutaneously with BTV serotype 3 (BTV-3), a foreign isolate with unknown pathogenicity in North American livestock, and with North American serotype 11 (BTV-11). Erythrocyte-associated BTV RNA was detected earlier and at greater concentrations in sheep treated with immunosuppressive drugs. Similarly, viral RNA and infectious virus were detected in blood monocytes earlier and at higher frequency in immunosuppressed animals: as many as 1 in 970 monocytes revealed BTV RNA at peak viremia, compared to <1 in 10(5) monocytes from immunocompetent sheep. Animals infected with BTV-3 had a higher virus burden in monocytes and lesions of greater severity than those infected with BTV-11. BTV RNA was detected by in situ hybridization in vascular endothelial cells and cells of monocyte lineage, but only in tissues from immunocompromised animals, and was most abundant in animals infected with BTV-3. In contrast, reverse transcription-in situ PCR showed BTV RNA from both viral serotypes in high numbers of tissue leukocytes and vascular endothelial cells from both immunosuppressed and, to a lesser extent, immunocompetent animals. Collectively, these findings show that BTV infection is widely distributed during acute infection but replication is highly restricted in animals with normal immunity. These findings also suggest that in addition to virulence factors that define viral serotypes, immunosuppression could play a role in the natural history of orbivirus infection, allowing for higher virus burden, increased virus persistence, and greater potential for acquisition of virus by the arthropod vector.

Human herpesvirus 8 in the prostate glands of men with Kaposi's sarcoma.

The epidemiology of human immunodeficiency virus (HIV)-associated Kaposi's sarcoma (KS) resembles that of a sexually transmitted pathogen. However, human herpesvirus 8 (HHV-8), the proposed cause of KS, is found in semen only infrequently and at low titers. To determine whether HHV-8 was present in the urogenital tract, transrectal ultrasound-guided prostate biopsies were obtained from six men with KS (five with concurrent HIV infection) and four without KS (three with concurrent HIV) and assayed for HHV-8 by PCR. Nine of the 10 men were seropositive for HHV-8. Five of nine HHV-8-seropositive men had HHV-8 DNA detected in prostate tissue by solution-based PCR. All five currently had KS or had it previously. In two subjects, prostate tissue was the only identified source of HHV-8. In situ PCR on serial sections of prostate indicated that HHV-8 infection was localized to discrete areas of the prostate. When detected, HHV-8 DNA was present in the nuclei of >90% of the glandular epithelial cells. In situ hybridization for HHV-8 mRNA revealed that between 1 and 5% of cells harboring HHV-8 DNA expressed viral transcripts associated with HHV-8 replication (T1.1 transcript), while >90% expressed gene products associated with viral latency (T0.7 transcript). Intermittent replication of HHV-8 in the prostate and subsequent shedding of virus in semen may be crucial factors for determining whether HHV-8 can be transmitted through sexual activity.

Epizootic hemorrhagic disease: analysis of tissues by amplification and in situ hybridization reveals widespread orbivirus infection at low copy numbers.

A recent outbreak of hemorrhagic fever in wild ruminants in the northwest United States was characterized by rapid onset of fever, followed shortly thereafter by hemorrhage and death. As a result, a confirmed 1,000 white-tailed deer and pronghorn antelope died over the course of 3 months. Lesions were multisystemic and included severe edema, congestion, acute vascular necrosis, and hemorrhage. Animals that died with clinical signs and/or lesions consistent with hemorrhagic fever had antibody to epizootic hemorrhagic disease virus serotype 2 (EHDV-2) by radioimmune precipitation but the antibody was limited exclusively to class immunoglobulin M. These findings, indicative of acute infection, were corroborated by the observation that numerous deer were found dead; however, clinically affected deer were rarely seen during the outbreak. Furthermore, only in animals with hemorrhagic lesions was EHDV-2 isolated and/or erythrocyte-associated EHDV-2 RNA detected by serotype-specific reverse transcription (RT)-PCR. By using a novel RT in situ PCR assay, viral nucleic acid was localized to the cytoplasm of large numbers of tissue leukocytes and vascular endothelium in tissues with hemorrhage and to vessels, demonstrating acute intimal and medial necrosis. Because PCR amplification prior to in situ hybridization was essential for detecting EHDV, the virus copy number within individual cells was low, <20 virus copies. These findings suggest that massive covert infection characterized by rapid dissemination of virus facilitates the severe and lethal nature of this disease.

Peripheral blood eosinophilia in owl monkeys is associated with increased eosinophilopoiesis yet depressed recruitment kinetics to the Chemokine RANTES.

New world nonhuman primates of the genus Aotus (owl monkeys) can be categorized by 11 distinct karyotypes (K). It has been demonstrated that monkeys of K-VI persistently have one order of magnitude more eosinophils (EOS) in the peripheral blood than K-I monkeys. The purpose of this study was to investigate the basis for this difference and examine EOS recruitment using two cutaneous models of inflammation. Peripheral blood EOS were isolated on metrizamide gradients to > or = 95% purity and then used for phenotypic studies. There were no significant differences when comparing karyotypes in the ratio of normodense (K-I, 6.4% +/- 3.8%; K-VI, 21.1% +/- 8.8%) EOS or their survival in culture (K-I, 5.3% +/- 2.9% at 72 hours; K-VI, 2.8% +/- 0.7% at 72 hours) (P > .05). Examination of bone marrow revealed that K-VI monkeys had greater than fivefold more EOS and EOS precursors than K-I animals. To examine EOS function in recruitment, monkeys of each karyotype were given a single intradermal injection of Escherichia coli lipopolysaccharide (LPS) or human recombinant (PMN) and mononuclear cells occurred in response to LPS as early as 4 hours after injection; the severity of infiltration was similar in both karyotypes and at all time points up to 24 hours. In contrast, by 8 hours after intradermal injection of RANTES, leukocyte infiltration in K-I monkeys consisted mostly of PMN (94.8% +/- 0.7%) that were predominantly EOS. In comparison, there was essentially no infiltrate in K-VI animals at all time points. There was no difference in VCAM-1 expression in response to intradermal LPS or RANTES between the two karyotypes. These results suggest that the genetic basis of peripheralblood eosinophilia in K-VI owl monkeys is likely a function of heightened eosinophilopoiesis and depressed recruitment kinetics from the peripheral circulatory pool in response to RANTES.

Venereal shedding of ovine lentivirus in infected rams.

OBJECTIVE: To assess shedding of ovine lentivirus (OvLV) in semen of infected rams with or without epididymitis. DESIGN: Rams 1 and 2 were naturally infected with OvLV. Rams 3-6 were inoculated with OvLV strain 85/ 34. Ram 7 was inoculated with uninfected cell culture supernatant (OvLV-negative control). 14 weeks after OvLV inoculation, rams 1-3, 6, and 7 were inoculated with Brucella ovis into the epididymis. Ram 4 was a natural case of B ovis epididymitis, and ram 5 was left noninoculated (B ovis-negative control). Blood mononuclear cells (BMNC) and semen were collected between 0 and 44 weeks after OvLV inoculation. ANIMALS: Seven 2- to 3-year-old rams. PROCEDURE: Infective OvLV in BMNC and semen was determined by virus isolation and subsequent OvLV-DNA amplification by polymerase chain reaction (PCR). Bronchoalveolar lavage cells collected after death were used for DNA extraction and PCR amplification. RESULTS: OvLV was detected in the semen of rams 3 and 6, but only after B ovis inoculation. OvLV was isolated consistently from BMNC of rams 3 and 6, but only occasionally from rams 1, 2, 4, and 5. Leukocytospermia was evident in every ejaculate of all B ovis-infected rams after infection. Semiquantitative PCR determination of OvLV DNA from bronchoalveolar lavage cells revealed the highest OvLV DNA load in rams 3 and 6. CONCLUSIONS: Leukocytospermia and a high virus load in infected animals are important factors that determine shedding of OvLV in semen. CLINICAL RELEVANCE: Dissemination of OvLV through contaminated semen could have important implications in the epidemiology and control of this infection.

Virological markers in cerebrospinal fluid are predictive of ovine lentivirus-associated subclinical encephalomyelitis.

Encephalomyelitis is a sequela to ovine lentivirus (OvLV) and human immunodeficiency virus infections. Examination of autopsy tissue from 38 naturally infected asymptomatic sheep showed that 7 (18%) had subclinical neurological lesions characterized by perivascular and periventricular infiltrates of lymphocytes and histiocytes in the leptomeninges, cerebral white matter, choroid plexus, and/or cervical spinal cord. Intralesional histiocytes were shown to contain lentiviral capsid proteins or RNA. Infectious virus (2/7), viral proteins (4/7), and antiviral antibody (5/7) were only detected in cerebrospinal fluid (CSF) from animals with central nervous system (CNS) lesions associated with OvLV infection, suggesting that such virologic markers in CSF, when used concurrently, are predictive of pathologic changes specific to the CNS.

Pathologic and serologic responses of isogeneic twin lambs to phenotypically distinct lentiviruses.

Viral strain differences in the degree of lymphoid interstitial pneumonia (LIP) and in antibody responses to ovine lentivirus (OvLV) infection have been described in experimentally inoculated neonatal lambs. To rule out the possibility that these differences were due to differences in host genetic factors, one lamb from each of three sets of artificially produced identical twins was inoculated with a lytic strain of OvLV (85/34), and the corresponding twin was inoculated with a persistent strain (84/28). One lamb of a fourth set of twins was inoculated with the lytic strain of OvLV, and the corresponding twin was inoculated with a cell culture supernatant. The degree of LIP, as determined by histologic analysis of the lung sections collected at necropsy, was independent of the virus strain used for inoculation. The amount of OvLV proviral DNA in alveolar macrophages correlated with the degree of LIP. However, differences in the antibody response of genetically identical lambs to OvLV structural proteins indicated that the two strains have different in vivo immunogenic properties. The lack of difference in the degree of LIP between lambs with identical genetic backgrounds suggests that host genetic factors may be important in determining the degree of inflammatory response by the lung.

Ovine lentivirus expression and disease. Virus replication, but not entry, is restricted to macrophages of specific tissues.

To better define the relationship between lentivirus infection and lymphoproliferative or inflammatory disease, we studied postmortem specimens of 38 sheep naturally infected with ovine lentivirus (OvLV) and with different clinical manifestations of OvLV-associated disease. Immunohistochemistry, in situ hybridization, and virus isolation were used to localize viral protein, viral RNA, and infectious virus to specific cells and tissues. Viral protein or infectious virus was found in cells morphologically and histochemically compatible with macrophages (M phi s), but only in lung, bone marrow, mammary gland, lymph node, spleen, synovium, brain, and spinal cord, frequently in association with lymphocyte infiltrates. In contrast, viral RNA was found in a variety of cell types, including epithelium, M phi s, and M phi-like cells, and in a wider range of tissues, with or without OvLV-associated lesions. In summary, these findings suggest that in vivo: 1), OvLV can enter a variety of cell types, 2), productive infection is restricted to cells of M phi lineage, and 3), cells expressing viral proteins are limited to specific tissues, those associated with OvLV-induced diseases.

Macrophage function in simian AIDS. Killing defects in vivo are independent of macrophage infection, associated with alterations in Th phenotype, and reversible with IFN-gamma.

Infection of macrophages (M phi) in vitro with M phi-tropic isolates of simian immunodeficiency virus (SIV) did not affect killing of Cryptococcus neoformans up to 16 days after inoculation (p < 0.05). Conversely, alveolar M phi from animals with SIV-induced AIDS killed C. neoformans less efficiently (10.4 +/- 2.8% killing) and, when stimulated with phorbol myristate, produced less superoxide anion (O2-; 0.15 +/- 0.02 O2-/h/mg M phi protein) than M phi from uninfected monkeys (21.8 +/- 1.6% killing and 0.29 +/- 0.02 O2-/h/mg M phi protein). In contrast, killing and O2- release were accentuated in SIV+ asymptomatic animals (25.8 +/- 2.3% killing and 0.40 +/- 0.04 O2-/h/mg M phi protein; p < 0.05). M phi-mediated killing and O2- production could be restored by culturing the affected cells in supernatants derived from Con A-stimulated PBMC of uninfected or SIV+ asymptomatic monkeys. Supernatants with restorative properties had high IFN-gamma bioactivity (63.4 +/- 11.0 U/ml) and elevated IL-10 concentrations (75.3 +/- 10.4 pg/ml) as compared with PBMC supernatants derived from animals with AIDS (IFN-gamma, 9.7 +/- 4.9 U/ml; IL-10, 24.0 +/- 10.1 pg/ml). Functional restoration was found to be dependent, in part, on the presence of IFN-gamma, as neutralizing Abs to IFN-gamma significantly inhibited functional restoration in active supernatants. Moreover, the inactivity of supernatants from mitogen-stimulated PBMC cultures derived from animals with AIDS was not solely dependent upon the loss of CD4+ lymphocytes, inasmuch as purified pulmonary alveolar and peripheral blood CD4+ T cells from only uninfected and SIV+ asymptomatic animals, and not those from animals with AIDS, produced IFN-gamma upon mitogen stimulation. Collectively, these findings suggest that functional aberrations in alveolar M phi from animals with AIDS are not directly due to virus infection but likely result from changes in the pulmonary microenvironment in association with the multisystemic loss and dysfunction of CD4+ T cells.