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Biomedical subjects

R A Robins

Publications and source records attributed to R A Robins.

At least 109 records · Page 6Linked to original sources
PubMed1982

Phenotype of rat natural killer cells defined by monoclonal antibodies marking rat lymphocyte subsets.

The fluorescence-activated cell sorter and a rosette-depletion technique were used to separate rat spleen lymphocytes and BCG-activated lymphocytes into subpopulations with and without the antigens defined by W3/13, W3/23 and OX8 monoclonal antibodies. The resultant populations were then tested for natural killer (NK) activity in a quantifiable 6 hr 51Cr release assay. The data establish that rat natural killer cells are heterogeneous with respect to their surface antigen expression and that subpopulations of rat NK cells express the OX8 and W3/13 defined antigens. However, rat NK cells do not express the antigen defined by W3/24 monoclonal antibody.

Animals↗
PubMed1981

Report on international comparative evaluation of possible value of assays for immune complexes for diagnosis of human breast cancer.

There have been several reports on the possible value of measurements of circulating immune complexes for the diagnosis of human breast cancer. To begin to evaluate this possibility and the comparability of results among laboratories, a cooperative study was organized under the auspices of the International Agency for Research on Cancer and the National Cancer Institute (NCI) of the United States. Investigators from four laboratories performing assays for immune complexes were sent coded aliquots of serum specimens from the NCI-Mayo Clinic Serum Bank. The serum panel consisted of specimens from 30 patients with breast cancer (including 20 from untreated patients with resectable tumors), 30 preoperative patients with benign breast disease, and 30 normal women. Although some significant differences in levels of immune complexes between cancer patients and controls were seen, none of the assays had sufficient discriminatory capacity to support optimism about the diagnostic value of this approach. To relate the results with immune complexes to those with a widely used cancer marker, the same sera were also tested for levels of carcinoembryonic antigen (CEA). The CEA assay provided significant discrimination between cancer patients and normal donors but did not significantly discriminate between malignant and benign breast diseases.

Antigen-Antibody Complex↗
PubMed1981

Procoagulant activity of human mononuclear leukocytes: dissociation of the effect of mitogens on procoagulant activity and mitogen-stimulated lymphocyte proliferation.

The role of mononuclear cells in generating procoagulant activity was examined by incubating Ficoll-Hypaque-separated mononuclear leukocytes with or without mitogens (phytohemagglutinin, pokeweed mitogen, and concanavalin A). The procoagulant activity was assayed by a modification of a one-stage plasma recalcification time. Significant procoagulant activity developed after 24 hr incubation and was dose dependent; mitogens alone had no effect on the clotting time. The increase in activity was paralleled by the increase in tritiated thymidine incorporation into replication DNA. However, mitomycin C had little inhibitory effect on the development of procoagulant activity, whereas thymidine incorporation was inhibited. The major procoagulant activity was associated with intact cells and not the conditioned supernatant. The removal of adherent mononuclear cells (mostly monocytes) by polystyrene bead columns abolished the procoagulant activity, whereas purification of mononuclear leukocyte populations for monocytes markedly increased the activity as compared to purified lymphocytes. The procoagulant activity was shown to act by the extrinsic limb of the coagulation sequence because of substitution factor VII-deficient plasma for normal plasma resulted in marked depression of procoagulant activity, whereas factor VIII-deficient plasma resulted in a clotting time only minimally longer then normal plasma. Thus, although procoagulant activity in cultures of mononuclear cells is stimulated by the mitogen reagent, these studies suggest that the activity may not be the result of the mitogenic effect on lymphocytes per se. Whether it is a direct effect of the mitogen on the adherent cell or is an effect of a contaminant of the mitogen reagent, such as endotoxin, remains to be determined.

Adult↗
PubMed1980

Circulating immune complexes in patients with bone tumours.

Sera from 62 patients with osteogenic sarcoma and 12 with malignant giant-cell tumour were tested for the presence of immune complexes by the 125I-Clq binding assay. Elevated serum Clq binding activity was found in 67.7% of the osteogenic sarcoma patients and in 75% of the giant-cell tumour patients. These results were compared with those obtained with five sera from patients with benign bone tumours and 20 sera from normal young donors. In the last two groups, the incidence of elevated Clq-binding activity was 0% and 5%, respectively. In some patients with giant-cell tumours, pre- and post-operative serum samples were studied, showing a decrease in test values after tumour resection. Preliminary sequential studies of individual patients indicate that the 125I-Clq binding assay may be useful for monitoring patients with bone tumours.

Adolescent↗
PubMed1980

Tumour markers with unknown functions in gynaecological neoplasia.

Pre- and post-operative ovarian cancer patients' sera were examined for the presence or circulating immune complexes using a variety of assay procedures. In contrast to findings with breast cancer patients' sera, sera from patients with other gynaecological tumours or with preclinical disease diagnosed by cytology, no evidence was obtained to indicate that circulating immune complexes were associated with ovarian cancer.

Antigen-Antibody Complex↗
PubMed1979

Modification of the immunogenicity and antigenicity of rat hepatoma cells. I. Cell-surface stabilization with glutaraldehyde.

gamma-Irradiated rat hepatoma cells are immunogenic in syngeneic WAB/Not rats, so that immunized animals are protected against tumour-cell challenge and circulating tumour-specific antibody is produced. Treatment of the immunizing cells with glutaraldehyde at concentrations of 0.001% or greater for 30 min rendered these cells non-protective in tumour-rejection tests and no longer able to induce significant formation of specific antibody. However, tumour-specific antigens were shown to be expressed upon treated cells; they specifically bound tumour-specific antibody from syngeneic immune sera assessed in indirect membrane-immunofluorescence tests. Also, these cells specifically absorbed antibody from immune or tumour-bearer sera, as demonstrated in the indirect membrane-immunofluorescence test or a complement-dependent 51Cr-release test. Alloantigen expression was not influenced by glutaraldehyde treatment, although glutaraldehyde-treated hepatoma cells failed to induce alloantibody formation in KX/Not rats. Polyacrylamide-gel electrophoresis of treated cells, surface-labelled with 125I, indicated that extensive cross-linking of the surface protein occurred as a result of glutaraldehyde treatment. The present findings establish that although the expression of a tumour-specific antigen is necessary for the induction of immuno-protection against tumour-cell challenge, this alone is not a sufficient condition for eliciting tumour immunity.

Animals↗
PubMed1979

Spontaneous development of cytotoxic activity in cultured lymphnode cells from tumour-bearing rats.

Incubation in vitro of lymphnode cells (LNC) from rats bearing a transplanted syngeneic methylcholanthrene-induced sarcoma (Mc7) resulted in the generation of a potent cytotoxic activity. Four to seven days' culture was required for development of cytotoxic activity, which was shown to be mediated by a heat-stable soluble factor. The cytotoxicity was not detectable in a 3 h or 15 h 51Cr-release assay, but was demonstrated in a 48 h microcytotoxicity assay, where post-labeling with isotopically labelled cell precursors was used to quantitate cell survival. The cytotoxicity of the cultured tumour-bearer LNC and their supernatant factor was shown to be cross-reactive for tumour cell lines other than sarcoma Mc7, and was also expressed against adult or embryonic fibroblasts.

Animals↗
PubMed1978

Studies on the microcytotoxicity test. II. The uptake of amino acids ([3H]leucine or [75Se]methionine) but not nucleosides ([3H]thymidine or [125I]IUdR) or 51CrO24-provides a direct and quantitative measure of target cell survival in the presence of lymphoid cells.

We have studied the suitability of various commonly used radioactive materials for the direct post-labeling of adherent rat target cells in long-term cytotoxicity tests. The use of nucleosides at high concentration avoids the necessity of adding fluorodeoxyuridine to enhance nucleoside uptake by target cells, and reduces the degree of non-specific inhibition of nucleoside uptake caused by products released from effector lymphoid cells. However, when [125I]iododeoxyuridine was used for labelling, such inhibition was not completely avoided even at very high nucleoside concentration, necessitating the washing of target cells prior to labelling. Similarly, without prewashing, the uptake of 51CrO24-ions frequently failed to correlate well with the numbers of surviving target cells as assessed by cell counting. On the other hand, radiolabelled amino acids, when present at semi-saturating concentrations, were taken up quantitatively by target cells under all conditions tested. Furthermore, in comparison to [125I]iododeoxyuridine, radioactive amino acids showed little if any toxicity to target cells. The use of the gamma-emitting amino acid analogue, [75Se]selenomethionine, is particularly recommended.

Animals↗
PubMed1977

Circulating immune complexes in patients with breast cancer.

In a retrospective study in women with breast cancer circulating immune complex levels were measured by radioimmunoprecipitation with 125I-Clq. Before operation all the patients showed plasma immune complex levels significantly higher than those in controls. Twelve months after mastectomy patients identified clinicopathologically as having a good prognosis had almost normal levels of immune complexes. By contrast, patients with detectable dissemination on diagnosis or those who died within 22 months after mastectomy had significantly raised plasma levels. The tumour-specific nature of the immune complexes detected remains to be shown and suggestions about the applicability of this test not only for prognosis but also for monitoring the course of malignant diseases need to be confirmed by further investigations.

Antibody Specificity↗
PubMed1976

Single step separation of human T and B cells using AET treated srbc rosettes.

A technique for the single step separation of human thymus derived (T) and Bursa equivalent (B) lymphocytes was developed. Density separation of B lymphocytes and T lymphocyte-sheep red blood cell (SRBC) rosettes on Ficoll-Hypaque was modified by pretreatment of the SRBC with 2 aminoethylisothiouronium bromide hydrobromide. This modification yielded significantly purer populations of T and B cells. Up to 15 X 10(7) were separated without increasing contamination allowing for the recovery of B lymphocytes as well as T lymphocytes in sufficient numbers to use in functional assays.

B-Lymphocytes↗