Immune complex-dissociated p24 antigen in congenital or perinatal HIV infection: role in the diagnosis and assessment of risk of infection in infants.

Immune complex-dissociated (ICD) HIV-1 p24 antigen assay is a rapid technique for assessing the presence of HIV gag or core protein in plasma or serum. In this study, ICD p24 antigen detection in HIV-1 infected mothers and their infants enrolled in the Women and Infants Transmission Study (WITS) was evaluated primarily as a diagnostic assay for HIV-1 detection in young infants and for its association with perinatal transmission. Plasma from 47 infected infants and 160 uninfected infants was examined, along with plasma from 197 of their mothers who had a delivery or close-to-delivery specimen. ICD p24 antigen was detected in plasma of 27.3% of infected infants at birth and in 70% to 81% at 1 to 6 months. The diagnostic specificity at birth was 90% and 98% to 100.0% at 1 to 6 months. The ICD p24 antigen concentration correlated with concurrent quantitative HIV culture results. The risk of transmission from mother to infant was higher if the mother had detectable ICD p24 antigen at or near the time of delivery (p = 0.002), but its presence did not accurately predict transmission (positive predictive value of 36%, negative predictive values of 85%). The relative ease of performing the ICD p24 antigen assay and the low cost compared with that of HIV culture or DNA PCR makes this test a useful adjunct for the diagnosis of perinatal HIV infection and for enhancing understanding of its pathogenesis, particularly where cost and availability limit access to more sensitive assays.

Diagnosis of human immunodeficiency virus type 1 infection in infants by immune complex dissociation p24 assay.

Using immune complex dissociation (ICD), we retrospectively examined serum and plasma of 206 infants aged 0 to 4 months who were perinatally exposed to human immunodeficiency virus (HIV). All samples were analyzed in a blinded manner. Infection status was determined based on the results of HIV culture and Centers for Disease Control and Prevention classification. The overall diagnostic sensitivity of the assay was 59% (93 samples, 73 infants), and specificity was 100% (160 samples, 133 infants). When the samples were analyzed according to age, sensitivity was highest at age 1 to 2 months (17 of 21 infants, 81%). Sensitivities at other ages were 53% at < 1 month, 55% at 2 to 3 months, and 48% at 3 to 4 months (9 of 17, 11 of 20, and 12 of 25 cases, respectively). In 11 evaluable cases there was a possible correlation of p24 antigen quantitation (in picograms per milliliter) with disease progression. We conclude that, as determined in this study, the ICD p24 is a rapid diagnostic assay for HIV infection with a sensitivity of >80% at 1 to 2 months of age and 100% specificity, as evaluated, up to 4 months of age.

Quantitative relationship of circulating p24 antigen with human immunodeficiency virus (HIV) RNA and specific antibody in HIV-infected subjects receiving antiretroviral therapy. The RV43 Study Group.

To better understand the biologic meaning and potential clinical utility of p24 antigen measurements in human immunodeficiency virus (HIV) infection, p24 antigen and antibody and HIV RNA were quantitated in parallel. Specimens (n = 311) were analyzed from 74 participants in a zidovudine treatment study. Parallel antigen and RNA measurements revealed the frequent occurrence of two types of discordant results. First, p24 antigen was often not detected in samples with high antibody levels even when > 10(6) RNA copies/mL were present. Second, in specimens in which p24 antigen was detected, the concentration was greater than expected on the basis of HIV RNA values. These results suggest that optimal use of serum p24 antigen values will require consideration of both specific antibody levels and non-virion associated antigen.

Detection of simian immunodeficiency virus and human immunodeficiency virus type 2 capsid antigens by a monoclonal antibody-based antigen capture assay.

We have tested the ability of a monoclonal antibody-based simian immunodeficiency virus (SIV) p27 capsid antigen assay to detect SIV antigen in supernatants from a variety of infected cell cultures. The antigen capture assay has a sensitivity of approximately 30 pg of SIV p27 capsid antigen/ml. The assay detected SIV p27 capsid antigen in cell culture supernatants from all six strains tested, detected the replication of SIV following the inoculation of the virus in peripheral blood mononuclear cell cultures earlier compared to reverse transcriptase assay, and was more sensitive in detection of the SIV antigen compared to human immunodeficiency virus type 1 (HIV-1) antigen capture assays. The SIV antigen capture assay was used to detect SIV antigen from serum samples and tissue cultures from eight of eight SIVB670-infected rhesus macaques (Macaca mulatta). Similar samples from four control rhesus macaques were negative when tested by the assay. The SIV antigen was detected in virus-infected monkeys during early time periods following inoculation (1 to 3 weeks) or during episodes of CD4+ lymphocytopenia and clinically evident disease. In addition, the SIV antigen capture assay positively identified each of three different HIV-2 strains in cell culture supernatants. The SIV antigen capture assay provides a sensitive and specific method to monitor SIV and HIV-2 capsid antigen in cell cultures and from infected animals. The assay will be an important tool in the utilization of SIV and HIV-2 primate models for HIV-induced acquired immunodeficiency disease syndrome.

Rapid serologic testing with immune-complex-dissociated HIV p24 antigen for early detection of HIV infection in neonates. Southern California Pediatric AIDS Consortium.

BACKGROUND: Serologic detection of human immunodeficiency virus (HIV) infection in neonates is complicated by the presence of immune complexes, consisting of passively transferred maternal antibodies and HIV antigens. A new, rapid assay has been designed to disrupt these immune complexes in order to permit the detection of a specific HIV antigen. We evaluated the efficacy of this assay in detecting HIV infection in neonates. METHODS: We measured p24 antigen in blood samples from both infected and uninfected children of HIV-infected mothers. The samples were treated with glycine hydrochloride to dissociate the immune complexes, followed by neutralization with TRIS-hydrochloric acid. A commercial HIV p24 antigen assay was then used, with an optical density greater than 0.120 at a wavelength of 450 nm defined as indicating a positive result. RESULTS: Of eight cord-blood samples from neonates with proved HIV infection, five were positive for immune-complex-dissociated p24 antigen. For two other neonates the first postnatal sample, obtained on days 12 and 18, was positive. There was no follow-up sample for the eighth neonate. Of 22 uninfected neonates, 20 were negative on the cord-blood assay. Two neonates had positive cord-blood samples, but the first postnatal sample was negative. Thus, the tests with early postnatal samples identified the HIV-infection status correctly for all 29 children who could be evaluated. In a separate group of 78 children (median age, 188 weeks), the specificity of the test was 100 percent and the sensitivity 81 percent. CONCLUSIONS: The immune-complex-dissociated HIV p24 antigen assay is a rapid, simple serologic test that may be of value in diagnosing HIV infection in neonates born to HIV-infected women.

Development of a monoclonal antibody-based p24 capsid antigen detection assay for HTLV-I, HTLV-II, and STLV-I infection.

A monoclonal antibody-based antigen capture enzyme-linked immunosorbent assay (ELISA) was developed and employed to detect p24 capsid antigen from human T-cell lymphotropic viruses type I and II (HTLV-I, HTLV-II), simian T-cell lymphotropic virus type I (STLV-I)-infected cell lines, and from mononuclear cell cocultures of HTLV-infected humans and STLV-I infected monkeys. A monoclonal antibody specific for HTLV p24 and p53 capsid antigens was coated onto 96-well microtiter plates to capture HTLV/STLV antigen. Captured antigen was then detected by the addition of a polyclonal, biotinylated human anti-HTLV-I antibody, and color developed with tetramethyl benzidine/H2O2 substrate. As little as 15 pg/ml of HTLV-I p24 antigen could be detected in this assay. Culture supernatants from HTLV-I-infected cell lines (HUT-102, MT-2, C5/MJ, HTLV-II-infected cell lines (Mo-T, Mo-B, PanG 12.1, NRA) and STLV-I-infected cell lines (Matsu, NEPC M39) were all positive in the assay. In addition, p24 was detected from peripheral blood mononuclear cell (PBMC) cocultures of 8 of 8 (100%) HTLV-I diseased patients, 14 of 20 (70%) HTLV-I and HTLV-II-infected, asymptomatic persons, and 8 of 8 (100%) STLV-I-infected, asymptomatic monkeys. Culture supernatants of cells infected with human immunodeficiency virus type (HIV-1), simian immunodeficiency virus (SIV), Chlamydia trachomatis, cytomegalovirus (CMV), herpes simplex I and II (HSV), feline leukemia virus (FELV), bovine leukemia virus (BLV), and bovine immunodeficiency virus (BIV) were all negative. Similarly, normal human peripheral blood mononuclear cells and uninfected, transformed human T cells, were also negative in the assay.(ABSTRACT TRUNCATED AT 250 WORDS)

Cervical carcinoma antigen: distribution in neoplastic lesions of the uterine cervix and comparison to other tumor markers.

Four antibodies (anti-CCA, anti-CEA, Ca-l, and anti-EMA) were used to study the distribution of antibody-binding sites in normal endocervical mucosa, metaplastic squamous epithelium, squamous epithelium exhibiting varying grades of intraepithelial neoplasia, and invasive squamous cell carcinoma. Anti-CCA, a novel monoclonal antibody raised against an extract of squamous cell carcinoma of the cervix, recognizes dysplastic, neoplastic, and metaplastic cervical epithelial cells. While anti-CCA and Ca-l rarely stained normal glandular epithelium, 31.4 and 45.7% of the samples stained positively for CEA and EMA, respectively. There did not appear to be significant differences between anti-CCA and the other antibodies in the frequency with which neoplastic conditions were stained. Based upon these observations, it appears that none of the antibodies tested can be regarded as a specific tumor marker.

Cervical carcinoma antigens in the diagnosis of human squamous cell carcinoma of the cervix.

The use of tumor-associated antigens (TAA) in the diagnosis of human squamous cell carcinoma of the cervix was evaluated by immunofluorescence staining of second cervical scrapes and touch preparations of normal and carcinomatous tissue. Rabbit antisera, prepared against human cervical squamous cell carcinoma homogenates and absorbed with normal human cervix and plasma, were used to stain 103 second cervical scrapes by indirect immunofluorescence. Of these specimens, 59 were positive by immunofluorescence, whereas the remaining 44 were negative. Compared with conventional cytologic diagnosis, positive immunofluorescence was detected in 100% (49/49) of the second scrapes from patients with cervical dysplasia or carcinoma (for a false-negative rate of zero). Of the second cervical scrapes from 57 patients negative by cytology, 13 were positive by immunofluorescence (for a false-positive rate of 22.8%). Indirect immunofluorescence tests on tumor touch preparations also revealed cervical TAA in other types of gynecologic tumors.

Tumor-bound immunoglobulin in human gynecologic cancers.

By the use of immunofluorescence techniques, immunoglobulin of the IgG class was consistently found in touch preparations and in frozen sections of squamous cell carcinomas of the uterine cervix (both keratinizing and nonkeratinizing) and in an adenosquamous cell carcinoma of the cervix, an adenocarcinoma of the cervix, a mixed mesodermal-uterine tumor, and a uterine adenocarcinoma metastasized to the ovaries. Trace amountsof IgM were found in 1 squamous cell carcinoma and in 1 adenocarcinoma of the cervix. Except for 1 tumor specimen consisting primarily of infiltrating lymphocytes that stained positive for human IgG, IgM, IgA, and C3, the tumors were consistently negative for IgA and C3. Specimens made from normal cervical tissue were uniformly negative for all immunoglobulins and complement. Positive staining for human IgG could be eliminated by incubation of the tumor preparations with unconjugated goat antihuman IgG before the preparations were stained with fluorescein isothiocyanate-conjugated goat antihuman IgG. Attempts to elute the tumor-bound IgG with glycine-HCl buffer (pH 2.2) were most successful with the use of unfixed tissue, although the positive staining for IgG could not be entirely eliminated. The elution effects of the low-pH buffer on tissue fixed over 2 hours in 10% Formalin were minimal.