POS0782 FOLLICULAR DENDRITIC CELL NETWORKS IN MINOR SALIVARY GLAND BIOPSIES: A MARKER OF DISEASE ACTIVITY AT BASELINE AND DURING THE FOLLOW-UP IN SJÖGREN’S SYNDROME

Background:

Minor salivary gland biopsy (MSGB) has been increasingly recognized as an important tool for the stratification of patients with primary Sjögren’s syndrome (pSS). Recently, the presence of follicular dendritic cell (FDC) networks in the inflammatory infiltrate has been associated with more severe biological and serological abnormalities compared with less organized infiltrates.

Objectives:

To investigate the associations between the presence and number of FDC networks in foci and pSS glandular and extra-glandular disease activity at baseline and during the follow-up.

Methods:

Consecutive MSGBs performed in daily practice for clinically suspected pSS from January 2017 to October 2020 were reviewed. Patients’ demographic, clinical, biological and serological data were obtained from medical records. The ESSDAI was used to measure disease activity at baseline and at the end of the follow-up in pSS patients. For histopathology, 3 µm sections were cut from each formalin-fixed paraffin-embedded block of MSGBs and stained with haematoxylin and eosin (H&E). Immunohistochemical stainings were performed on additional 3 μm sections in order to detect T lymphocytes (CD3), B lymphocytes (CD20) and follicular dendritic cells (CD21). Glandular tissue areas, number of foci, focus score (FS) and the presence and number of FDC networks were assessed.

Results:

We reviewed 330 consecutive MSGBs from patients with suspected pSS: out of them 146/330 (44%) were classified as nonspecific chronic sialadenitis (NSCS) whereas 184/330 (56%) as focal lymphocytic sialadenitis (FLS). According to the ACR/EULAR criteria the diagnosis of pSS was confirmed in 130 patients (117 F:13 M, age 56±13 yrs). The mean (S.D) surface area of the MSGBs was 7.8 (3.9) mm2. The number of foci in the FLS samples ranged from 1 to 12 (mean (S.D)=3.1 (2.6)), whereas the FS ranged from 0.3 to 9.0 (mean (S.D) = 1.4 (1.2)).The presence of FDC networks was documented in 106/330 (32%) of the samples; in 54/106 (51%) of these MSGBs the number of FDC networks ranged from 2 to 8 (mean (S.D)=3.1 (1.4)). The number of FDC networks significantly correlated with the number of foci (r=0.721**) and FS (r=0.707**). Patients with FDC networks in the inflammatory infiltrate presented more serological abnormalities (i.e anti-Ro/SSA, anti-LA/SSB, Rheumatoid factor) and elevated IgG levels (p<0.001). In pSS patients, the number of FDC networks slightly correlated also with C4 levels (r=-0.216*), peripheral lymphocyte count (r=-0.274**) and with glandular (r=0.213*), and biological (r=0.230**) domains of the ESSDAI at baseline. After a mean (S.D) follow-up of 21(13) months, the number of FDC networks still correlated with the final total ESSDAI (r=0.312**).

Conclusion:

The presence and number of FDC networks in foci represent a useful histopathological parameter able to reflect disease activity at baseline and during the follow-up, thus allowing more personalized interventions.

Disclosure of Interests:

None declared

Building Capacity for Evidence-Informed Priority Setting in the Indian Health System: An International Collaborative Experience

India's rapid economic growth has been accompanied by slower improvements in population health. Given the need to reconcile the ambitious goal of achieving Universal Coverage with limited resources, a robust priority-setting mechanism is required to ensure that the right trade-offs are made and the impact on health is maximised. Health Technology Assessment (HTA) is endorsed by the World Health Assembly as the gold standard approach to synthesizing evidence systematically for evidence-informed priority setting (EIPS). India is formally committed to institutionalising HTA as an integral component of the EIPS process. The effective conduct and uptake of HTA depends on a well-functioning ecosystem of stakeholders adept at commissioning and generating policy-relevant HTA research, developing and utilising rigorous technical, transparent, and inclusive methods and processes, and a strong multisectoral and transnational appetite for the use of evidence to inform policy. These all require myriad complex and complementary capacities to be built at each level of the health system . In this paper we describe how a framework for targeted and locally-tailored capacity building for EIPS, and specifically HTA, was collaboratively developed and implemented by an international network of priority-setting expertise, and the Government of India.

Lymphatic endothelial cells derived from metastatic and non-metastatic lymph nodes of human colorectal cancer reveal phenotypic differences in culture

Colorectal cancer is one of the most frequent causes of death in Western countries. Most patients develop metastasis traveling through the lymphatic system, and regional lymph node metastasis is considered a marker for dissemination, increased stage, and worse prognosis. Despite rapid advances in tumor biology, the processes that underpin lymphatic invasion and lymph node metastasis remain poorly understood. The aim of this study was to establish an easy protocol for isolation of pure tumor lymphatic endothelial cells derived from lymph nodes to study differences compared with normal endothelial cells of uninvolved tissue from the same patients. Cells were isolated with very high purity via magnetic cell sorting and express the specific lymphatic markers Prox-1 and Lyve-1. They show differences in expression of adhesion molecules, chemokines, and growth factor secretion, and capability to form capillaries when seeded on basal membrane, thereby, revealing important differences between the two cell type. These cultures may provide a promising platform for the comparative analysis of both cell types at the molecular and biological level and to optimize treatment strategies.

Evaluation of three different manual techniques of sharpening curettes through a scanning electron microscope: a randomized controlled experimental study

OBJECTIVE

The purpose of this study was to compare the effectiveness of three different techniques for manually sharpening of periodontal curettes (PCs) by examining the blades with the aid of scanning electron microscope (SEM).

METHODS

Three groups were considered based on three sharpening methods used: group A (moving a PC over a stationary stone); group B (moving a stone over a stationary PC) and group C (moving a PC over a stone fixed, placed on a 'sharpening horse'). After the sharpening, the blades were examined using SEM. The SEM images were assessed independently by five different independent observers. An evaluation board was used to assign a value to each image. A preliminary pilot study was conducted to establish the number of samples. Pearson's correlation test was used to assess the correlations between measurements. anova test with Bonferroni's post hoc test was used to compare the three groups.

RESULTS

Sixty PCs (20 PCs per group) were used in this study. Statistically significant differences emerged between the three groups (P-value = 0.001). Bonferroni's test showed that the difference between groups A and B was not statistically significant (P-value = 0.80), while it was significant for the comparisons between groups A and C (P-value = 0.005) and between groups B and C (P-value = 0.001).

CONCLUSIONS

The sharpening technique used in group C, which involved the use of the sharpening horse, proved the most effective.

In vitro comparison of the bond strength to the enamel of conventional and self-etching dental fissure sealants

AIM

Dental caries in pits and fissures of molars is still very common in young people, despite a gradual reduction in their incidence and prevalence. Prevention with the aid of dental fissure sealants can help to reduce the onset of decay. In vitro tests were conducted to compare the bond strength to enamel of self-etching sealants versus those applied using the conventional procedure.

METHODS

The lingual surface of 40 extracted, caries-free, mandibular third molars was milled to make them flat. The prepared teeth were randomly divided into two groups of 20 teeth each: those in Group A were treated with Clinpro (3M ESPE, St. Paul, MN, USA); those in Group B with Quick Seal (BJM Laboratories Ltd, Or-Yehuda, Israel). Cylinders of sealant were attached to the enamel of the flat surfaces of the samples using a polymerisation process treating the surfaces involved according to the type of material. All samples underwent load testing by means of a universal test machine.

RESULTS

The results of the load testing, measured in MPa, were analysed using the Student's t-test for independent samples and the differences proved significant, indicating that the traditionally- applied sealant (mean strength 21.06 MPa) assured a significantly stronger bond (p <.05) than the self-etching sealant (mean strength 10.43 MPa) under our experimental conditions. CONCLUSION Conventional sealants generally provide a considerably higher bond strength than self-etching sealants.

Experimental assessment of oral hygiene achieved by children wearing rapid palatal expanders, comparing manual and electric toothbrushes

OBJECTIVES

The aim was to compare the efficacy of the electric versus the manual toothbrush in terms of the oral hygiene achieved by patients wearing rapid palatal expanders (RPEs).

METHODS

Forty patients were randomly divided into two groups; one equipped with a manual toothbrush (Group A), the other with an electric toothbrush (Group B). Each child's plaque index (PI) and gingival index (GI) were calculated at banded molar level at times T0 (before banding), T1 (a month later), T2 (3 months later) and T3 (when the expander was removed). At each appointment, the PI and GI were recorded and the patient was remotivated.

RESULTS

The level of oral hygiene achieved by the group using an electric toothbrush produced a greater improvement in the two indexes than in the group using the manual toothbrush that showed no statistically significant improvement (PI T0-T3: P = 0.309; GI T0-T3: P = 0.141). Both indexes dropped considerably in both groups from T0 to T2, but more so in the group B. From T2 to T3, although the electric toothbrush continued to be substantially more effective, Group B showed a statistically significant deterioration in the oral hygiene (PI +20%; GI +33%). Other assessments conducted on particular areas of the tooth showed improvements in the PI (-33%) for the vestibular region, and for the GI (-57%) in the palatal region among the patients in Group B, while there were no significant changes in these indexes in Group A.

CONCLUSIONS

Our findings show that the electric toothbrush is statistically more efficient in performing an adequate level of oral hygiene in children wearing RPE.

Experimental evaluation of two methodologies for the restoration of crown fracture in permanent anterior teeth

AIM

The purpose of this study is to compare, by means of mechanical tests, the resistance of two types of dental restoration in the uncomplicated crown fracture of human permanent maxillary central incisor: rebonding of the fractured tooth fragment and application of ceramic veneers.

MATERIALS AND METHODS

Thirty human maxillary central incisors were divided into three groups of ten teeth each. The teeth of the first group (Group A) were kept intact and used as controls, while the remaining teeth were sectioned, in order to simulate a crown fracture, and restored respectively with either the rebonding of the fragment (Group B) or with the use of ceramic veneers (Group C). All samples underwent mechanical tests by means of a universal test machine.

RESULTS

The mean resistance to fracture recorded is respectively 425.2N for Group A, 233.3N for Group B, and 347.3N for Group C. One-way ANOVA analysis demonstrates statistical significance for at least one couple of values (Group B compared to Group A). The group of restorations with rebonding of fractured fragments has a mean value of resistance to fracture that is lower than both intact teeth and teeth restored with ceramic veneers. The resistance of teeth with rebonded restorations is 54.9% of that of, intact teeth, and resistance increases for teeth restored with ceramic veneers (81.8% of that of intact teeth).

CONCLUSION

Ceramic veneers showed a higher resistance than rebonding and resulted to be more reliable in case of further trauma.

Treatment of hyperhomocysteinaemia in haemodialysis patients at high cardiovascular risk

OBJECTIVES

Cardiovascular disease (CVD) is the main cause of death among haemodialysis (HD) patients. Emerging cardiovascular risk factors such as oxidative stress and chronic inflammation are involved in these patients together with traditional risk factors. Here we investigate the effects of a short-term folate treatment on some markers of chronic inflammation in two groups of HD patients with and without vascular occlusive disease (VOD).

PATIENTS AND METHODS

Homocysteine (HCy), C-reactive protein (CRP), Folate, fibrinogen and alpha1 acid glycoprotein (alpha1AGP) were dosed before and after a 3-month course of high-dose folate (25 mg intravenous calcium laevofolinate pentahydride once weekly) and again after a one-month washout in 15 HD patients with established VOD (group A) and in 15 comparable HD patients with no diagnosis of VOD (group B).

RESULTS

Baseline HCy and CRP were significantly elevated in patients of both groups A and B compared to normal values. Folate treatment significantly reduced HCy in patients of both groups A and B and alpha1AGP only in patients of group A, while the other markers were not modified. After the one-month washout a significant raise of CRP could be observed in patients of group A; again, the other markers were not modified.

CONCLUSIONS

Our results suggest that significant reduction of serum HCy can be achieved in both patients with or without VOD after administration of high-dose folic acid. Hence, folic acid supply is useful in the treatment of hyperhomocysteinemia in HD patients, although it is not sufficient to modify their chronic inflammatory status.

Comparative evaluation of different techniques of surface preparation for occlusal sealing

AIM

Aim of this experiment is the efficacy evaluation of three different types of surface preparation techniques by microleakage assessment of two different sealing materials.

MATERIALS AND METHODS

Sixty teeth were used for the experiment: half were treated with Admira seal (Voco) and the remaining half with Delton FS+ (Dentsply). Each group was then divided into three subgroups, which underwent three different preparation techniques before sealant placement: mechanical brushing, air abrasion and Intensive bur FG 40D4, respectively. After immersion of the specimens in methylene blue solution, the degree of microleakage was assessed by mean of optic microscope.

RESULTS

Results show no microleakage in samples treated with air abrasion, followed by the samples treated with mechanical brushing. The teeth prepared by bur treatment before sealant application show a significant number and degree of marginal infiltration.

CONCLUSION

It can be concluded that air abrasion technique is able to guarantee a reliable seal of occlusal surfaces.

Immunotherapy with bovine aortic endothelial cells in subcutaneous and intracerebral glioma models in rats: effects on survival time, tumor growth, and tumor neovascularization

High-grade gliomas are aggressive tumors of the central nervous system characterized by endothelial cell proliferation and a high degree of vascularity. Conventional antitumoral treatments (i.e., surgery, radiotherapy, and chemotherapy) do not achieve satisfactory results (median survival in glioblastoma 12-18 months). It has been suggested that immunotherapy with xenogenic endothelial cells could slow tumor growth rate in a number of tumors in a murine model, but the study did not include gliomas. In experiments performed in our laboratory, vaccination with proliferating bovine aortic endothelium increased survival time in Fischer rats inoculated intracerebrally with 9L. Immunotherapy was also able to reduce the growth of subcutaneously injected 9L gliosarcoma cells in Fischer rats and to decrease microvessel density within the tumors, in the absence of major organ toxicity. Immunoglobulins (Ig) in the sera from vaccinated rats stained bovine aortic endothelium as well as human umbilical vein endothelium in active proliferation. Moreover, immune sera from immunized rats stained microvessels of human malignant glioma specimens and vessels of intracerebrally implanted tumors. Two proteins of MW of 11 and 19 kDa were identified by Western blot as targets of Ig elicited by vaccination. A possible future development is to select peptides/proteins suitable for vaccination in humans, avoiding the biohazards connected with xenogenic whole-cell vaccination.

Reversible immobilization of engineered molecules by Ni-NTA chelators

Electrochemical synthesis of nickel-nitrilotriacetic acid (Ni-NTA) chelators, for subsequent immobilization of (His)(6)-tagged proteins (Photosystem II (PSII) as model molecule), on Au or Au-graphite electrodes is compared to chemical synthesis. Results show: (i) higher Ni-NTA surface density, (ii) shorter treatment time (1-12 min vs. 16 h normally needed for self-assembled monolayer (SAM)), (iii) possibility of addressing the chelator to only one Au electrode, in a sensor micro-array.

Six-month and 12-month mental health outcome of medical and surgical patients admitted to general hospital

BACKGROUND

We have recently reported a two-phase study on psychiatric morbidity in a sample of general hospital patients. This paper reports the results of the 6-month and 12-month follow-up of these patients.

METHODS

The screening questionnaire was the GHQ-12. The main diagnostic instrument used in the second phase was the CIDI-PHC. All patients who had been interviewed with CIDI-PHC (N = 363) were followed-up and the baseline assessment was compared with the scoring on questionnaires administered in the 6-month postal enquiry and with the psychopathological status at 12-month, elicited with a telephone structured interview.

RESULTS

Sixty-two and 87% of patients completed the 6- and 12-month follow-up assessment respectively. The first follow-up indicated no significant decrease in the level of symptoms. The 12-month follow-up interview showed that 23% of males and 40% of females had poor/mostly poor mental health. The logistic model showed that females with a definite ICD-10 diagnosis, admitted to a medical department, who had consumed psychotropic drugs in the previous year, had the most unfavourable outcome. The risk of a poor/mostly poor outcome steadily increased with the severity of the psychopathology during hospitalization.

CONCLUSION

In medical and surgical general hospital patients the risk factors associated with a poor mental health outcome are similar to those found in primary care patients. Greater attention should be paid in assessing routinely mental health status of general hospital patients during hospitalization.

Evaluating psychiatric morbidity in a general hospital: a two-phase epidemiological survey

BACKGROUND

This study aimed to assess psychiatric morbidity and to collect information on disability, life events and family support in a representative sample of patients admitted to a general hospital.

METHODS

On the basis of information collected in a pilot study a systematic sample of patients consecutively admitted to seven general medical and seven surgical wards of the Academic General Hospital of Verona was selected and interviewed using a two-phase screening procedure and standardized instruments (GHQ-12, HADS, BDQ and CIDI-PHC). All data were analysed using appropriately weighted logistic regression procedures.

RESULTS

A total of 1039 patients completed the GHQ-12 and 298 (28.7%) were high-scorers: 363 patients were interviewed with CIDI-PHC. The prevalence of ICD-10 cases was 26.1%. The most common psychiatric diagnoses were current depression (12.8%) and generalized anxiety disorder (10.8%), followed by alcohol related disorders (5 %). A higher prevalence of ICD-10 cases was found in medical wards, among females, patients older than 24 years, unemployed and separated/divorced people. Life events were associated with psychopathology, and so was the number of disability days. Although 49.8% of ICD-10 cases were identified by the hospital doctors as having a psychological disorder, 23.1% of ICD-10 cases were referred to the liaison psychiatric service.

CONCLUSION

The results of the present study stress the need to collect epidemiologically-based data on psychological disorders and their recognition not only in general practice, but also in general hospital settings, in order to have a more complete picture of the pathways to specialist care.

Generation of CD28- cells from long-term-stimulated CD8+CD28+ T cells: a possible mechanism accounting for the increased number of CD8+CD28- T cells in HIV-1-infected patients

According to CD28 molecule expression, CD8+ T cells can be classed as CD28bright, CD28dim, and CD28-. The CD28dim T cells were found to derive from mitogenic stimulated CD28-T cells but also from CD28bright T cells through a mechanism of CD28 down-modulation. Moreover, after prolonged in vitro interleukin-2 stimulation, clonal CD28bright, cells showed a CD28dim expression before further evolution to a stable CD28-phenotype. This loss was concomitant with the disappearance of CD28 mRNA. A study of the cytokine production pattern revealed that CD28dim and CD28- T cell clones produced similar levels of type 1 and type 2 cytokines, which differed from those produced by the CD28bright T cell clones. A high percentage of CD28dim and CD28- cells, with similarities in their cytokine production pattern, were found in the blood samples of HIV-infected patients, as compared to healthy donors. The CD28 down-modulation may account for the increased number of CD8+CD28- T cells in HIV-infected patients.

The provision of psychiatric care in southern Italy. Results from the 'Psychiatry in Southern Italy's Services' (De PISIS) survey

OBJECTIVE

To describe structural features, attenders' characteristics and intervention habits in a large sample of Community Mental Health Departments (CMHDs) in Southern Italy.

DESIGN AND SETTING

1) Survey of resources and organization features of collaborating CMHDs; 2) Unreplicated registration of all attenders and of therapeutic interventions during an index week.

RESULTS

A self-selected sample of 47 CMHDs in Southern Italy recruited 3845 patients during the last week of October 1992. Participating CMHDs were serving a socially deprived and severely ill population: 45.8% of attenders had 8 years or less of formal education; only 18.9% were employed, 30.9% of diagnoses were of the schizophrenia spectrum group and 23% of the affective disorders group. Sixty-eight per cent of patients were being treated with psychotropic drugs, while only 19% received rehabilitative interventions. The activity of CMHDs were oriented more towards the control of active symptomatology than towards rehabilitation. A significantly higher proportion of patients receiving a schizophrenia-spectrum disorder diagnosis were found in contact during the index week with those CMHDs providing both residential and semiresidential (day-hospital, community center) facilities.

Persistence of human T cell lymphotropic virus type 1 (HTLV-1) sequences in peripheral blood mononuclear cells from patients with mycosis fungoides

Mycosis fungoides (MF) is a rare form of cutaneous T cell lymphoma suspected of having a viral etiology. As in adult T cell leukemia, the virus involved may be human T lymphotropic virus type 1 (HTLV-1). We cultured the peripheral blood mononuclear cells (PBMC) of 29 patients with MF HTLV-1 seronegative by enzyme-linked immunosorbent assay and Western blot. The presence of reverse transcriptase (RT) and p24 antigen was investigated in the concentrate supernatant of the culture. The DNA of all studied patients was submitted to polymerase chain reaction and Southern blot analysis using primers and probes recognizing the tax region of HTLV-1/2 and the pol region of HTLV-1. 10 of 29 patients were found positive to HTLV-1, whereas they were always negative to RT and p24. The same results were confirmed in double blind after 6 mo. Our findings suggest HTLV-1 may be involved in the etiology of MF, at least in certain cases.

Effect of subinhibitory concentrations of lomefloxacin on bacterial adherence

We studied the effect of subinhibitory concentrations of lomefloxacin on bacterial adherence, assessing the presence of fimbriae in E. coli and the adherence to uroepithelial cells of Staphylococcus saprophyticus. The degree of inhibition of fimbriae in E. coli in the log-phase is directly proportional to subminimal inhibiting concentrations (sub-MIC). On the contrary, there is no effect when the bacteria are in a stationary phase. In the case of Staphylococcus saprophyticus the adherence to epithelial cells was observed at concentrations of 1/2 and 1/4 the MIC.

Development of a flow cytometric assay for the detection and measurement of neutralizing antibodies against human immunodeficiency virus

Cells infected with human immunodeficiency virus type 1 (HIV-1) develop viral antigens which can be detected by immunofluorescence. We developed a flow cytometric immunofluorescence assay (FIFA) which provides a quantitative analysis of HIV-1 p24 using a monoclonal antibody (mAb) as a specific reagent. The reduction of HIV p24 antigen expression in viral infected cells was then used to determine HIV neutralizing antibody titers in human sera. Results obtained by FIFA for detecting neutralizing antibodies against HIV-1, when compared with results obtained by indirect immunofluorescence assay (IFA), showed an overall index of agreement of 94.1%. The correlation between the neutralizing antibody titers obtained with each method was found to be highly significant (ro = 0.8; p < 0.01). The simple methodology and the adaptability of this FIFA to various assay conditions make it suitable for routine purposes and for assessing the efficacy of vaccination strategies.

Purification of natural human IFN-gamma antibodies

Natural antibodies to interferon gamma (IFN-gamma) were found in patients suffering from various viral infections, but also at weak titers in healthy individuals. In the present study we describe a one-step chromatographic procedure for the purification of the anti-IFN-gamma antibodies from human Ig preparations, using a recombinant IFN-gamma-coupled Sepharose CL4B affinity column. The antibodies to IFN-gamma were eluted from the column using 3 different methods without loss of immunological activity. They were found to be Ig, mostly of the IgG1 subclass, and, in the biological assay, to be able to neutralize the de novo expression of Fc receptor sites induced by IFN-gamma on U937 cells.

Natural antibodies to IFN-gamma in man and their increase during viral infection

Natural antibodies to IFN-gamma were found in healthy individuals ranging from newborn babies to adults and, at higher levels, in patients suffering from different viral infections. During a viral infection, the titer of anti-IFN-gamma antibodies was observed to be correlated with the stage of the disease. Antibodies specific to IFN-gamma were affinity purified both from sera taken from healthy individuals and sera from viral-infected patients, by using a rIFN-gamma-coupled CNBr-activated Sepharose 4B column. The antibodies were found to be of the IgG class, and maintained their ability to bind rIFN-gamma. They were then tested for neutralizing activity and none of the IgG preparations we analyzed impaired the antiviral activity of rIFN-gamma. This finding suggests that the antigenic determinants recognized by these antibodies on the IFN-gamma molecule are located outside the site, on the IFN-gamma molecule, responsible for its antiviral activity.

Natural antibodies to IFN-gamma in man and their increase during viral infection

Natural antibodies to IFN-gamma were found in healthy individuals ranging from newborn babies to adults and, at higher levels, in patients suffering from different viral infections. During a viral infection, the titer of anti-IFN-gamma antibodies was observed to be correlated with the stage of the disease. Antibodies specific to IFN-gamma were affinity purified both from sera taken from healthy individuals and sera from viral-infected patients, by using a rIFN-gamma-coupled CNBr-activated Sepharose 4B column. The antibodies were found to be of the IgG class, and maintained their ability to bind rIFN-gamma. They were then tested for neutralizing activity and none of the IgG preparations we analyzed impaired the antiviral activity of rIFN-gamma. This finding suggests that the antigenic determinants recognized by these antibodies on the IFN-gamma molecule are located outside the site, on the IFN-gamma molecule, responsible for its antiviral activity.

Interferon-gamma is associated with the surface of the human immunodeficiency virus and binds to the gag gene product p17

Purified HIV-1 antigen preparations produced in cell culture were found to contain interferon-gamma (IFN-gamma). Electron microscopic examination of HIV-1 released by H9 cells, a cell line found to produce IFN-gamma, showed the presence of this molecule on the surface of the virus particle. The HIV-1 protein p17 was found to bind IFN-gamma by a solid-phase radioimmunoassay. The specificity of the reaction was confirmed by Western blot analysis. This finding opens new questions about the biologic role of IFN-gamma itself and of its interaction with HIV.