An enzyme immunoassay for the measurement of HLA-DR antigen expression

Immunoenzymatic assay that measures the expression of murine histocompatibility antigens in macrophages and lymphocytes

A convenient--simple, sensitive, rapid and reproducible--enzyme immunoassay to measure H-2 particulated and solubilized cellular antigens is described. Cellular antigens were measured by ELISA through the binding of specific biotinylated antibodies and streptoavidin-peroxidase conjugate to cells in suspension. Endogenous peroxidase activity of activated cells was inhibited by addition of sodium azide and H2O2 in acid conditions. The assay proved capable of distinguishing between two cell lines (EL-4/H-2b and P815/H-2d) and even between the cells of three congenic mouse strains (BALB/B, H-2b, BALB/c, H-2d, and BALB/K, H-2k) and was sensitive to as few as 2.5 x 10(4) cells/well. Results were comparable to those obtained with FACS. An inhibition version of this assay was found to be very useful for the detection of H-2 antigens present in whole antigen cells extracts.

Decreased monocyte-mediated angiogenesis in scleroderma

Scleroderma is a disease characterized by proliferative vascular lesions in which monocytes/macrophages may play a key role. Monocytes were isolated from 14 scleroderma patients and 11 normal controls and cultured with or without lipopolysaccharide (LPS) (5 micrograms/ml). Monocyte-conditioned medium was assayed in the rat corneal bioassay for angiogenesis. Conditioned medium from normal monocytes was nonangiogenic, as was conditioned medium from scleroderma monocytes. While conditioned medium from LPS-activated normal monocytes was potently angiogenic in 11/13 corneas, conditioned medium from LPS-activated scleroderma monocytes was angiogenic in only 3/14 corneas. Levels of the angiogenic cytokine tumor necrosis factor-alpha (TNF-alpha) were measured in conditioned medium from scleroderma and normal monocytes. TNF-alpha levels were not significantly different in patient and control groups and thus do not account for the decreased angiogenic activity exhibited by scleroderma monocytes. As monocytes require activation to produce angiogenic activity, we determined the cell surface binding of monoclonal antibodies to activation-related (HLA-DR, 3D8, and 8D7) and other (Leu-M5) markers on monocytes by radioimmunoassay. Monocytes were cultured alone, with LPS (5 micrograms/ml), or with interferon-gamma (IFN) (200 units/ml). The usual increase in binding of anti-HLA-DR on stimulation of scleroderma monocytes with IFN was slightly less than that of controls. IFN-stimulated monocytes bound less anti-8D7 than controls. Anti-3D8 and anti-Leu-M5 binding was comparable in both groups. These results suggest that scleroderma monocytes do not produce normal levels of angiogenic activity with LPS stimulation, have some altered markers of activation on their cell surfaces, and may thus contribute to the aberrant vascular proliferation found in this disease.

High serum levels of CD8 antigen in primary biliary cirrhosis: a possible cause of suppressor cell dysfunction?

Reduced suppressor cell number and function have been described in a number of autoimmune diseases and this may contribute to pathogenesis. Suppressor cell function depends upon the interaction of the CD8 antigen expressed on suppressor cells with other limbs of the immune system. Recently, soluble membrane antigens including CD8 have been identified in serum and it is possible that the loss of such antigens from viable cells could result in functional deficit. In order to examine whether the decreased suppressor cell function reported in autoimmune type of chronic liver disease is associated with soluble serum CD8 levels, sera from 23 patients with primary biliary cirrhosis (PBC), 12 with autoimmune chronic active hepatitis (AI-CAH) and 21 healthy controls were tested using a commercially available enzyme immunoassay. The proportion of cells expressing the CD8 antigen and the intensity of its display were also determined using an immunofluorescent technique and an ELISA, respectively, for 12 PBC and 10 healthy controls. The soluble serum CD8 levels were significantly higher in PBC (mean U/ml +/- s.d., 777 +/- 331), and AI-CAH (575 +/- 291) than controls (322 +/- 115) (P less than 0.001 and P = 0.004, respectively). While the intensity of CD8 antigen expression on suppressor/cytotoxic populations was not significantly different in PBC (347 +/- 125 per 10(4) cells) compared with controls (441 +/- 206), the mean proportion of CD8 positive cells was significantly less in PBC (14.1 +/- 6.8%) than controls (20 +/- 4.7%) (P less than 0.05). These data suggest that the apparent reduction in suppressor cell number found for patients with PBC and AI-CAH may be a consequence of the shedding or secretion of CD8 antigen from cell membrane of CD8 positive lymphocyte. It is also possible that the loss of this antigen is responsible for the reduced suppressor cell function seen in these conditions.

Intrasplenic immunization for the induction of humoral and cell-mediated immunity to nitrocellulose-bound antigen

Intrasplenic immunization of mice has been shown to induce both specific humoral and cell-mediated immunity to minute amounts of nitrocellulose-bound antigen, electroblotted from sodium dodecyl sulfate-polyacrylamide gels. The test antigens used were aberrantly expressed molecules immunoprecipitated from the lysate of highly immunogenic ('xenogenized') murine lymphoma cells, derived by mutagenesis from a parental, nonimmunogenic cell line. The stained bands of nitrocellulose blots corresponding to the appropriate molecular weights were cut out and the resulting strips deposited in the spleens of recipient mice on three occasions at 15 day intervals. 2 weeks later, the antibody response in the serum was analyzed using a standard ELISA procedure. Cell-mediated immunity was investigated in vitro in terms of cytotoxic T lymphocyte (CTL) activity to radiolabeled xenogenized tumor target cells. In vivo, the immunized mice were assayed for their ability to mount a delayed-type hypersensitivity (DTH) response following footpad challenge with the xenogenized tumor. Our results confirm previous data that the intrasplenic deposition of minute amounts of protein immobilized on a solid matrix effectively stimulates production of specific antibodies. In addition, our results demonstrate that this procedure may also result in the development of T cell-dependent responses detectable in in vitro and in vivo assays of cell-mediated immunity.

Effects of recombinant human interferon gamma on human thyroid tissues from patients with Graves' disease and normal subjects transplanted into nude mice

We have attempted to determine whether interferon gamma (IFN gamma) would enhance, sustain or induce autoimmune thyroid disease (AITD) in xenotransplanted thyroid tissue from patients with Graves' disease or normal persons (actually paranodular tissue) in nude athymic mice, in the absence of an intact immune system. A dosage of 4000 U/mouse of human IFN gamma (hIFN gamma) was injected intraperitoneally daily for six consecutive weeks into the xenotransplanted mice. The parameters measured included the free T4 index, thyroid autoantibodies and TSH during the course of hIFN gamma injections. Thyroid epithelial cell (TEC) HLA-DR expression was measured in the thyroid tissue before xenotransplantation and at sacrifice; in addition, light and electron microscopic studies were carried out at those times. There were no significant differences in thyroid function between the control results and those obtained with hIFN gamma in either group of tissues. TEC HLA-DR expression was significantly increased by hIFN gamma in the normal group, but insignificantly in the Graves' group. In both light and electron microscopic observations, Graves' tissue (whether or not treated with hIFN gamma) was indistinguishable at sacrifice from normal thyroid tissue. The appearance had markedly altered from the same Graves' tissue examined at the time of the initial human surgery, which then showed the usual histological appearance of this disorder. We conclude that IFN gamma induced HLA-DR expression alone is not sufficient to sustain the ongoing process of AITD in this model.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of long-term, high-dose bovine thyrotropin administration on human thyroid tissues from patients with graves' disease and normal subjects xenografted into nude mice

We have attempted to determine whether the administration of thyrotropin would have any different functional or histological effects on Graves' tissue as opposed to human normal thyroid tissue in an in vivo situation (i.e., after xenograft into nude athymic mice). A dosage of 0.03 units per mouse of bovine thyroid-stimulating hormone (b-TSH) was injected intraperitoneally daily for 6 consecutive weeks into xenografted mice. The parameters measured included the free T₄ index and thyroid autoantibodies during the course of b-TSH injections. Tritiated (³H)-thymidine incorporation into thyroid epithelial cells (TECs) and TEC HLA-DR expression were measured in the thyroid tissue at the time of human surgery and at sacrifice; in addition, light-microscopical observations were made at those times. Although there was a decline in free T₄ index values during the course of the study, there was light-microscopical evidence suggestive of hyperplasia in both types of xenografted thyroid tissue. The TSH appeared to result in thyrocyte down-regulation, possibly of receptor or postreceptor origin. The administration of the b-TSH seemed to induce TEC HLA-DR expression in this study. Because these results differ from the effects of TSH on TEC in vitro with respect to TEC HLA-DR expression, it may be postulated that there are other factors liberated in vivo in the nude mice that interact with the TEC and TSH and initiate the TEC HLA-DR expression. We conclude that there are no significant differences between the responses of Graves' tissue and the normal human thyroid tissue in these studies.

Effects of supernatants of peripheral blood mononuclear cells stimulated by thyroid microsomal antigen on thyrocyte HLA-dr expression in vitro

Supernatants of 5 day cultures of peripheral blood mononuclear cells (PBMC) stimulated by thyroid microsomal antigens (TMA), and liver microsomal antigens (LMA) have been utilized to induce HLA-DR expression on human thyroid epithelial cells (TEC). The PBMC were obtained from 8 normal control persons and 13 patients with autoimmune thyroid disease (AITD) (7 Graves' disease and 6 Hashimoto's thyroiditis). The TEC HLA-DR expression was measured by an enzyme-linked immunosorbent assay (ELISA) technique. TEC HLA-DR expression was calculated as follows: (experimental optical density-control optical density) x 10(3): TEC HLA-DR index: % HLA-DR expression of IFN gamma 100 U/ml stimulation; and stimulation index (SI): TEC HLA-DR expression index induced by PBMC supernatants with antigen stimulation/TEC HLA-DR expression index induced by PBMC supernatants without antigen stimulation x 100. Supernatants without antigen stimulation from both normal control subjects and patients were able to induce TEC HLA-DR expression only minimally: 36.7 +/- 32.6 (mean +/- SD) TEC HLA-DR index for normal controls and 21.3 +/- 15.5 TEC HLA-DR index for AITD (not significant). The SI curves of both TMA and LMA were significantly different between control and AITD using two-way ANOVA test (p less than 0.01). TMA-stimulated PBMC supernatants from the patients increased TEC HLA-DR expression when compared to basal level using paired t-test; TMA 1 ng/ml, SI 179 +/- 99, less than 0.05.(ABSTRACT TRUNCATED AT 250 WORDS)

Enzyme-linked bio-immunoassay for IFN-gamma by HLA-DR induction

A novel enzyme-linked bio-immunoassay (bio-ELISA) has been developed to detect interferon-gamma (IFN-gamma) induced HLA-DR antigen on the surface of human tumor cells. Cells are cultured at 37 degrees C in 96-well microtiter plates in the presence of IFN-gamma for 2 days. After fixation with reagent alcohol the HLA-DR antigen is detected using a monoclonal antibody, followed by goat anti-mouse IgG-HRP conjugate. Four human cell lines were evaluated and all expressed HLA-DR in response to IFN-gamma in a dose-related fashion. Based on sensitivity, reproducibility and absence of antiproliferative effect by IFN-gamma, the COLO 205 cells (colon adenocarcinoma) were determined to be optimal. The bioassay is sensitive to 0.3 ng/ml IFN-gamma with a range to 10 ng/ml. The specificity of HLA-DR induction by IFN-gamma was demonstrated using an isotype specific monoclonal antibody as well as IFN-gamma neutralizing monoclonal and polyclonal antibodies. The effect of other cytokines on HLA-DR induction with COLO 205 cells was also investigated in this bioassay and only IFN-beta and interleukin-1 (IL-1) showed slight induction of HLA-DR. IFN-alpha had no effect at the concentration tested. Evaluation of assay parameters including reproducibility, sensitivity, simplicity, speed, cost and ability to standardize support the conclusion that this bioassay is a substantial improvement over the routinely used viral inhibition assay as a measure of IFN-gamma biological activity. The bio-ELISA technique also has potential applications for the quantitation of other cellular surface antigens induced by cytokines.