Search PubMed⌕ Search

Biomedical subjects

R K Gupta

Publications and source records attributed to R K Gupta.

At least 649 records · Page 36Linked to original sources
PubMed1983

Humoral response of melanoma patients to two different tumor-associated antigens.

Sera of 8 stage II melanoma patients undergoing surgical adjunctive immunotherapy with bacille Calmette Guérin (BCG) plus melanoma cell vaccine (MCV) were assayed for humoral response by the complement-dependent antibody cytotoxicity (CDAC) assay and by the microcomplement fixation (MCF) test. The patients developed high levels of cytotoxic (CTX) and complement-fixing (CF) antibodies to the UCLA-SO-M14 (M14) cells, one of the three melanoma cell lines in the MCV. Significant rises in CTX and CF antibodies occurred one month post-immunotherapy. While the level of CTX antibodies was maintained for 11 months thereafter, the titer of CF antibodies was sustained for seven months, then gradually declined. When the sera were absorbed with lymphoblastoid (ML14) cells which are autologous to the M14 cells, two residual peaks of CTX antibodies, one and four months postimmunotherapy and two peaks of CF antibodies, one and seven months postimmunotherapy, emerged. Two sera that exhibited high levels of CTX and CF antibodies one month postimmunotherapy were absorbed with ML14 cells and human fetal brain tissue. The reactivity of one serum in both the CDAC and MCF assays were abolished, whereas the reactivity of the other serum was not significantly diminished in either assay. These data indicate that the stage II post-surgical melanoma patients developed a humoral immune response to at least two distinct tumor antigens on the membrane of the M14 cells. One of these antigens appeared to be of fetal origin (OFA), the other M14-associated (TAA). Both antigens, OFA and TAA, were involved in complement-dependent antibody cytotoxic and complement fixation reactions in vitro.

Animals↗
PubMed1983

Nature of antigens and antibodies in immune complexes isolated by staphylococcal protein A from plasma of melanoma patients.

Immune complexes (IC) were isolated from plasma of melanoma patients by absorption to staphylococcal protein A and subsequent elution with MgCl2. The isolated ICs were purified by precipitation with polyethylene glycol and sucrose density gradient ultracentrifugation after radioiodination with 125I. The purified ICs were dissociated and radiolabeled antigen/antibody components were separated by ultracentrifugation at low pH (2.6). Under these conditions, about 72% radioactivity of the purified IC remained in the light-density region as a wide band. After neutralization, 26%-60% radioactivity in the region of 5S sedimentation bound to immobilized autologous immunoglobulins, as opposed to a maximum of 23% to immobilized immunoglobulins from human normal serum. Significant levels (73%-77%) of radioactivity in 7S region bound to rabbit anti-human IgG immunobeads. Immunoprecipitation of the antigen fraction by allogeneic anti-melanoma and rabbit anti-melanoma antibodies followed by SDS-polyacrylamide gel electrophoresis revealed the presence of a fetal antigen (FA) and a melanoma tumor-associated antigen (TAA). In addition, the presence of auto-antigen(s) was indicated by using autologous antibody in immunoprecipitation. Immunoglobulins (IgG) isolated from purified IC bound to cultured melanoma, sarcoma, and normal fibroblasts, although the binding to sarcoma and normal fibroblasts could be inhibited by preincubation of isolated IgG with soluble FA but not with soluble melanoma TAA. Thus, results of this investigation provide evidence that circulating IC in melanoma patients are composed of at least IgG and different antigens, and some of these antigens are produced by their tumor.

Antibodies, Neoplasm↗
PubMed1983

Immunochemical characterization of fetal antigen isolated from spent medium of a human melanoma cell line.

A fetal antigen (FA) was isolated from spent culture medium of a melanoma (M14) cell line. Allogeneic serum samples from melanoma patients, previously characterized with respect to anti-FA activity, were used as the source of anti-FA antibody. The FA activity was partially purified by membrane ultrafiltration, gel filtration, and chloroform:methanol extraction. The partially purified FA was then used to develop an enzyme-linked immunosorbent assay (ELISA). By indirect ELISA both the IgG and IgM classes of anti-FA antibodies were detected in the sera of cancer patients and normal volunteers. The incidences of anti-FA antibodies in the sera of cancer patients and normal volunteers were not significantly different. As detected by competitive inhibition in ELISA, FA activity was widely distributed among melanoma, sarcoma, and carcinoma tumor tissues and cultured tumor cells, as well as among fetal brain, skin, and muscle tissues. FA activity was destroyed by treatment with beta-galactosidase and hyaluronidase, but it was not destroyed by proteolytic and lipolytic enzymes. The antigen bound to immobilized ricin, peanut, and soybean lectins. FA activity in material purified by ricin-affinity chromatography was associated with molecules in the 60,000- to 70,000-dalton region as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. These results suggest a glycoprotein nature for the FA isolated from the spent culture medium of melanoma (M14) cells; this FA apparently elicits formation of natural antibodies in the cancer patients and normal donors.

Antigens↗
PubMed1983

Detection of tumour associated antigen in eluates from protein A columns used for ex vivo immunoadsorption of plasma from melanoma patients by radioimmunoassay.

Tumour associated antigen (TAA) of defined specificity and anti-TAA antibodies were isolated by elution with 0.1 M glycine-HCl buffer (pH 3.5) and 2.5 M MgCl2 from non-viable Staphylococcus aureus used in ex vivo immunoadsorption of plasma from four melanoma patients. The anti-TAA antibody activity in the MgCl2 eluate was determined by its ability to bind a melanoma 125I-TAA. The melanoma 125I-TAA was isolated and purified from the spent culture medium of a human melanoma cell line. The activity and specificity of TAA in the glycine-HCl eluates were determined by competitive inhibition in a radioimmunoassay in which melanoma 125I-TAA and an allogeneic antiserum obtained from a melanoma patient were used as the reagents. Results indicated that 0.04-0.81% of the total protein contained in the glycine-HCl eluates was TAA. The proportion of TAA to total protein in these eluates varied from patient to patient and treatment to treatment. Inhibition by the glycine-HCl eluates in the competitive radioimmunoassay was dose-dependent. Similarly, binding of melanoma 125I-TAA in a direct radioimmunoassay decreased with decreasing amounts of the anti-TAA antibody fraction. Quantitative analysis revealed that the MgCl2 eluates contained anti-TAA protein at levels ranging from 0.15 to 5.78% of total protein. Because both TAA and anti-TAA activities were found in eluates from S. aureus (protein A positive) used for immunoadsorption of plasma from melanoma patients, and because melanoma 125I-TAA isolated and purified from a human melanoma cell line did not bind to protein A directly, the results indicated that TAAs immunologically similar to the melanoma TAA were circulating in the form of immune complexes in plasma of four patients with melanoma and that these complexes could be removed from plasma by ex vivo immunoadsorption.

Antibodies, Neoplasm↗
PubMed1983

Prognostic significance of urinary antigen analysis by enzyme-linked immunosorbent assay in melanoma patients.

Urine samples collected from normal donors and melanoma patients were analyzed for the presence of tumor-associated antigen by competitive inhibition in the enzyme-linked immunosorbent assay (ELISA) using an allogeneic melanoma serum as the source of antibody and partially purified urine from the same donor as the target antigen. The results were expressed as antigen units (ng antigen protein/mg creatinine). The antigen levels in urine of melanoma patients (median = 56.5, N = 56) were significantly higher (P less than 0.05) than those of normal donors (median = 1.9, N = 56). The 90th percentile for the normal group was 34.3 antigen units. Using this value as the criterion for positivity, 36 of 56 (64%) urine samples of melanoma group were positive for the antigen as opposed to only 6 of 56 (11%) of normal donors. Subsequently, a retrospective analysis of 58 melanoma patients paired on the basis of disease recurrence and no recurrence after lymphadenectomy revealed a median antigen level of 68 units for the recurrent group and 18.9 for the nonrecurrent group. Eighteen of 29 (62%) melanoma patients who had recurrence of their disease and 9 of 29 (31%) patients who remained disease free were urinary antigen positive. These incidences were significantly different (P less than 0.005). The results of this investigation suggest that assessment of urinary antigen in stage I and II melanoma patients may prognosticate recurrence of the disease.

Antigens, Neoplasm↗
PubMed1983

On the noninvasive measurement of intracellular free magnesium by 31P NMR spectroscopy.

We previously introduced a noninvasive measurement of the concentration of free Mg2+ in intact cells and tissues using 31P NMR. To resolve a controversy in the literature concerning the affinity of Mg2+ for ATP used in our procedure, the apparent dissociation constant of MgATP under simulated intracellular conditions has been determined by three independent magnetic resonance methods, including a newly developed combination procedure for determining this value at intracellular ATP levels. The new combination method, which utilizes 31P NMR to determine the degree of Mg2+ chelation of ATP and the dye antipyrylazo III for optical determination of free Mg2+, yielded a value of (50 +/- 10) microM for this apparent dissociation constant at pH 7.2 in the presence of 0.15 M K+ and 25 degrees C. We further show that hydroxyquinolines are not satisfactory indicators for optical determination of the Mg2+-nucleotide dissociation constant. From our determinations a low value of free Mg2+ (less than 1 mM) is established for all of the tissues studied, including perfused heart muscle, contrary to a recent report in the literature. Saturating human erythrocytes with Mg2+ results in an alpha- and beta-phosphorus resonance separation for intracellular ATP that is indistinguishable from that observed in a noncellular MgATP control under similar conditions, showing that MgATP resonances in this cell are unaffected by the cellular environment.

Adenosine Triphosphate↗
PubMed1983

Occurrence and pathology of intracutaneous cornifying epitheliomas in Mastomys natalensis, the multimammate mouse.

Twelve mastomys (Mastomys natalensis) about two years old developed several raised, varying sized, multiple scurfy growths on most of the external parts of the body over a period of two months. No metastatic lesions were observed in the internal organs at necropsy. Histological examination of the cutaneous lesions revealed that the growths were comprised of intracutaneous cornifying epitheliomas.

Animals↗
PubMed1982

Relationship between circulating immune complexes and urinary antigens in human malignancy.

Urine samples obtained from patients with histologically proved melanoma and sarcoma were analyzed for the presence of tumor-associated antigens by complement fixation and enzyme immunoassay. Also, serum samples obtained during 24-hour urine collection from these patients were analyzed for circulating immune complexes by the complement consumption method and by the K562 radiometric assay. Of 36 cancer patients who were positive for urinary antigen (UA) by both assays, 28 (78%) were also positive for CIC in the two assays, six (17%) were positive in one of the two CIC-detection assays, and two (5%) were negative in both assays. Of 24 patients that were negative for CIC in both assays, ten (42%) were also negative for UA in both assays, i.e., complement fixation and enzyme immunoassay; 12 (50%) were negative by one of the two assays; and only two (8%) exhibited UA by both assays. This relationship was more striking for melanoma than sarcoma patients. In a melanoma patient whose samples were studied sequentially during his thermochemotherapy, the fluctuations in CIC and UA were parallel. These results suggest that excretion of tumor-associated antigen into urine is not an isolated phenomenon; rather, immune complex deposition in kidneys appears to cause glomerular damage which may allow the passage of the antigens into the urine.

Antigen-Antibody Complex↗
PubMed1982

Comparison of the techniques used for monitoring humoral immunity in cancer patients.

The humoral immune response to tumor-associated antigens (TAA) in cancer patients undergoing immunotherapy can vary considerably. This variability is inherent from patient to patient and is also dependent on the type of assay used to measure patient antibody response to tumors. In this investigation four serological techniques, complement-dependent antibody-mediated cytotoxicity, immune adherence, complement fixation, and indirect membrane immunofluorescence, were used to assess the humoral immune response in melanoma patients receiving specific immunization with cultured allogeneic melanoma cell vaccine. Two different patterns of antibody response were elicited. One was directed against TAA and oncofetal antigens (OFA) and the other was against HLA antigens. The sensitivity and reactivity varied among the different techniques suggesting that one test or technique may not be sufficient to evaluate critically a patient's response to immunotherapy.

Antibody Formation↗