Expression Of HLA Antigens Research Articles

BIOLOGICAL SIGNIFICANCE OF BETA hCG, HLA AND OTHER MEMBRANE ANTIGEN EXPRESSION ON BLADDER TUMOURS AND THEIR RELATIONSHIP TO TUMOUR INFILTRATING LYMPHOCYTES (TIL)

Expression of beta human chorionic gonadotropin (beta hCG) by bladder tumours has been shown to be associated with increased metastases and resistance to treatment with radiotherapy and chemotherapy. Preliminary results from typing frozen tumours using monoclonal antibodies against HLA determinants show reduced or lost expression of one or more antigens in two thirds of patients studied with a trend for more malignant behaviour and inability to generate tumour infiltrating lymphocyte expression using Interleukin-2 in those patients whose tumours demonstrate loss. In this series beta hCG expression was only seen in a subgroup of those demonstrating loss of HLA antigen expression. Studies of beta hCG secreting bladder cancer cell lines showed that it was possible to induce class II HLA antigen expression with gamma Interferon, and that this treatment but not alpha Interferon reduced beta hCG production by the cell line.

Induction of cell surface expression of HLA antigens by human IFN-gamma encoded by recombinant vaccinia virus.

A recombinant vaccinia virus (VV) encoding human IFN-gamma (VV-huIFN-gamma) was constructed and its effects on MHC Ag expression in human and murine cells in vitro analyzed by flow cytometry. At high multiplicities of infection (5 pfu/cell) the IFN-gamma expressed by vaccinia was not able to overcome the profound decrease of MHC concentration, normally associated with VV infection, in any of the cells tested. However, at successively decreasing multiplicities of infection, a gradual increase in MHC class I concentration above control levels was observed in human 143B cells but not in murine L929 cells, thus indicating that the species specificity of IFN-gamma is preserved in VV-huIFN-gamma-infected cells. We infer from these data that the IFN-gamma secreted by infected 143B cells is able to exert an MHC upregulating effect on uninfected cells in the vicinity. Antiviral activity of the IFN-gamma expressed by the virus was also assessed. Pretreatment for 24 to 48 h of human 143B cells with IFN-gamma containing supernatants had a significant antiviral effect comparable to rhuIFN-gamma. However, when added 1 h after virus infection, antiviral activity was much less evident. Also, the IFN-gamma secreted by infected 143B cells in monolayers infected at low multiplicity did not efficiently inhibit spread of infection to other cells in the vicinity.

Expression von Histokompatibilitäts-Antigenen an menschlichen Präimplantations-Embryonen

The expression of HLA antigens on polyploid human preimplantation embryos, obtained in an in vitro fertilization program, was investigated by indirect immunofluorescence test using a panel of well-defined monoclonal antibodies. Neither HLA class I antigens and beta 2-microglobulin, nor HLA class II molecules could be detected on blastomeres and the zona pellucida. It is supposed that the absence of HLA antigens on human preimplantation embryos may be one of the mechanisms important for the acceptance of the embryo by the immunocompetent mother.

HLA expression and function in single and double HLA-B27-transgenic mice.

The expression and function of HLA antigens in mice single transgenic for HLA-B27.2 (sTGM-B27.2) or double transgenic (dTGM) for HLA-B27.2 and human beta 2-microglobulin (h beta 2m) were compared. B27.2 could be well detected on the cell membrane of lymphocytes of sTGM. However, the expression in sTGM was much lower than in dTGM mice. Nevertheless, also in sTGM mice, the B27-transgene product possessed all functional properties of a class I HLA molecule. This was shown by the recognition and induction of antibodies and cytotoxic T cells, by the induction of "allo"-immunity, including skin graft rejection, and by the ability to present viral antigens. In dTGM, the expression of B27 on peripheral blood lymphocytes, spleen and lymphnode cells was comparable to H-2. However, on thymocytes, a relatively lower expression of HLA than H-2 was observed. This low expression of B27 on thymocytes is in concert with the observation that B27 is expressed only in the medulla of the thymus and not detectable in the cortex.

Interferon α and γ positive mononuclear cells and HLA antigen expression on hepatocyte membrane in the liver in chronic type B and non-A, non-B hepatitis

To evaluate the role of local interferon on pathogenesis in chronic type B and non-A, non-B chronic hepatitis, we examined the cellular localization of interferon alpha and gamma, and the expression of HLA antigens in cryostat liver sections from 33 chronic carriers of HBs antigen and 10 patients with non-A, non-B chronic hepatitis, using an immunoperoxidase procedure with monoclonal antibodies. Infiltrating mononuclear cells were the main cell element staining positive for interferon alpha or gamma. Among type B chronic liver disease, the percentages of both interferon alpha- and gamma-positive mononuclear cells were highest in patients with chronic active hepatitis, and their levels were higher in patients who had serum HBe antigen, indicating that local expression of interferon closely correlates with activity of disease and virus replication. On the other hand, both the frequency of interferon alpha or gamma positive cells, and the intensity of HLA class I antigens on hepatocytes were much lower in patients with non-A, non-B, chronic active hepatitis in comparison with those with type B chronic active hepatitis. These findings suggested that locally produced interferons have role of varying degrees on the host defence mechanism in chronic hepatitis, reflecting disease activity and the etiology of the disease.

Suitability of liquid-stored donor platelets in platelet compatibility testing.

Current platelet crossmatch procedures to select compatible donors for alloimmunized thrombocytopenic patients are hampered by the lack of a convenient platelet storage method. This study examined the feasibility of using washed apheresis donor platelets stored for up to 1 year in a modified Hank's buffer solution at 4 degrees C as crossmatch reagents in an indirect IgG-enzyme immunoassay. Pooled and monospecific HLA and PlA1 antisera were used to determine the antigenic reactivity of donor platelets in relation to duration of storage. There were no significant differences between mean HLA and PlA1 antigen expression in fresh and stored platelets. HLA reactivity was detected on 12 of 13 donor platelet samples stored for 3 to 9 months and on 14 of 17 platelets stored for 12 to 14 months. PlA1 reactivity was maintained at 12 to 14 months for all 12 donor platelet samples tested. In addition, incompatibility remained in 23 of 24 paired fresh and stored platelet crossmatches using individual alloimmunized patient plasmas. These data indicate that both HLA and platelet-specific PlA1 antigen reactivity can be maintained adequately in liquid storage at 4 degrees C for up to 1 year. The availability of a convenient platelet storage method should facilitate the general application of platelet crossmatching procedures for alloimmunized patients.

Class I and Class II HLA Antigen Expression by Transitional Cell Carcinoma of the Bladder: Correlation with T-Cell Infiltration and BCG Treatment

HLA class I and II glycoproteins from transitional cell carcinoma (TCC) and from perineoplastic and healthy vesical mucosa were characterized together with infiltrating cells by means of immunochemistry using specific monoclonal antibodies on frozen sections obtained during resection or radical cystectomy. Specimens were taken from 11 patients with TCC and five with healthy bladder mucosa. Four patients with TCC and four with healthy mucosa had been previously treated with a course of intravesical bacillus Calmette-Guerin (BCG). Ten out of 11 TCC samples expressed class I glycoproteins with a membrane pattern (diffuse in seven, focal in three) as normal epithelial cells from either controls or perineoplastic bladder. Interestingly, eight out of 11 TCC samples expressed class II antigens on their membrane that were also present in six cases in the perineoplastic tissue while the epithelial cells from four out of five normal bladders were completely negative. The epithelial display of class II antigens in the non-neoplastic areas and in the normal bladder correlates (p < 0.001) with the degree of cellular infiltrate while such a relationship was not found between the HLA II expression of neoplastic cells and the infiltrate. BCG treatment was associated with a higher amount of inflammatory cells, prevalently T “activated” cells (CD5+,DR+), with a CD4/CD8 ratio always >1. In the light of the role played by HLA glycoproteins in immune mechanisms, these results could help explain the positive action of BCG and the relative immunosensitivity of TCC.

HLA antigen expression and induction by gamma-interferon in cultured human trophoblast

HLA antigen expression and induction by gamma-interferon in cultured human trophoblast

HLA antigen expression on cultured human arterial endothelial cells.

Flow cytometric analysis and cellular assays were used to determine constitutive and induced expression of class I HLA antigens and class II antigens encoded by the HLA-DR, -DQ and -DP subregions on cultured human arterial endothelial cells (HAEC) derived from transplant donors. Class I but no or minimal quantities of class II HLA antigens were found on HAEC. Prior incubation of HAEC with gamma-IFN increased class I HLA antigen expression and induced class II HLA antigen expression on HAEC. The induced expression of HLA-DQ was lower than that of HLA-DR, but both were significantly reduced in comparison to the frequency of these antigens on EBV transformed lymphoblastoid cell lines derived from the same donor. In addition, supernatants from class I and class II alloreactive clones were shown to induce class II antigen expression on HAEC. By PLT analysis, it was shown that these antigens are functionally capable of generating a lymphocyte response. In this regard, HAEC have proved to be a helpful tool in designing in vitro lymphocyte-endothelial cell studies.

Differential lysis of melanoma clones by autologous recombinant interleukin 2-activated lymphocytes. Relationship with spontaneous resistance to doxorubicin (Dx).

To investigate whether human melanoma cells intrinsically resistant to autologous LAKs do exist, and whether a relationship between the level of lysis of LAKs and spontaneous drug resistance can be identified at the clonal level, we studied 44 clones obtained from a metastatic melanoma lesion. The antigenic phenotype of clones revealed a marked heterogeneity in the expression of HLA antigens of classes I and II. The clones were subsequently tested for sensitivity to autologous LAK and for spontaneous resistance to Dx. No clone resistant to autologous LAK was found, although a considerable range of lysis was noted with a normal frequency distribution. Growth in agar of the 2 clones in which lysis was least pronounced (6 and 26) was completely inhibited after co-culture with LAKs, indicating a lack of absolute resistance to these effectors. Spontaneous resistance to Dx, evaluated as ID50, revealed instead that the majority of clones had a low ID50. The frequency distribution of clones showed a left-skewed curve. The percentage of specific 51Cr-release and the ID50 for Dx could be correlated in 25 clones by linear regression. Sensitivity to LAK did not correlate with HLA classes I or II or melanoma-associated antigen expression. These results support the contention that increased LAK sensitivity of tumor cells is associated with drug resistance.

Expression of HLA Antigens on the Human Uvea

We examined the expression of HLA antigens on post-mortem human uveal tissues and on cultured uveal cells. There was no in vivo expression of class I or class II antigens in these tissues, except for the blood vessel endothelium which expressed class I but not class II antigens. Tissue cultured uveal cells were found to express class I antigens. The effect of interferon-alpha and interferon-gamma on the in vitro expression of these antigens was examined. Class I HLA antigen expression was enhanced by both interferon-alpha and interferon-gamma, while class II HLA antigens were induced on up to 100% of cultured cells, but only by interferon-gamma. These findings are discussed in their relation to immune mechanisms occurring in ocular inflammatory disorders.

Enhancement of class I HLA antigen expression by cytomegalovirus: role in amplification of virus infection.

We have investigated the effect of cytomegalovirus (CMV) infection on the expression of class I HLA antigens on fibroblasts in vitro. Scanning and integrating microdensitometry was used to quantitate the level of cytoplasmic class I antigen expression, and an antibody binding assay was used to quantitate cell surface expression of class I HLA molecules. CMV infection resulted in a significant increase in the level of cytoplasmic and cell surface class I HLA antigen expression of fibroblast monolayers. The maximal effect was seen at 72 hours postinfection and was observed with both the laboratory strain of CMV, strain AD169, and with CMV purified directly from clinical specimens. Part of the increased HLA expression was mediated by interferon released from infected cells; however, an additional direct effect of the virus itself has not been ruled out. Interferon-induced increased expression of class I HLA antigens was accompanied by increased binding of CMV to the cells, consistent with our recent demonstration that class I HLA molecules can function as a cellular receptor for CMV.

CYTOMEGALOVIRUS INFECTION AND DONOR/RECIPIENT HLA ANTIGENS: INTERDEPENDENT CO-FACTORS IN PATHOGENESIS OF VANISHING BILEDUCT SYNDROME AFTER LIVER TRANSPLANTATION

The contribution of cytomegalovirus (CMV) infection and its interrelation with HLA antigens in the development of chronic rejection (vanishing bile-duct syndrome—VBDS) was investigated in 101 patients surviving for at least 3 months after liver transplantation. A 1-2 antigen match for HLA DR antigens (30·9% vs 4·5% for zero DR match; p<0·002), a zero match for HLA A/B antigens (27·5% vs 10·9% for 1 or more A/B match; p <0·05), and active CMV infection (26·3% vs 4·4% for no CMV infection; p<0·005) were independently associated with an increased risk of VBDS. The coexistence of a 1-2 HLA DR match and CMV infection carried the highest relative risk (10·1) of VBDS; these two variables were probably interdependent since either alone was associated with a low relative risk (0·45 and 0·5). The association between VBDS and active CMV infection was not a consequence of alterations in immunosuppressive therapy. The findings would be consistent with precipitation of chronic rejection by CMV-induced HLA antigen expression in patients rendered susceptible by the donor/recipient HLA antigen match.

Expression of HLA antigens on renal tubular cells in culture. II. Effect of increased HLA antigen expression on tubular cell stimulation of lymphocyte activation and on their vulnerability to cell-mediated lysis.

Episodes of renal allograft rejection are characterized by an infiltrate of mononuclear leukocytes into the graft and increased HLA antigen expression by graft tubular cells. As HLA antigens are important immune-recognition molecules, we examined whether their increased expression during rejection might contribute to the rejection process. Interferon gamma (IFN-gamma)-treatment of cultured human kidney (HK) cells induced them to increase HLA antigen expression and caused a slight, but nonsignificant increase in their capacity to stimulate proliferation of allogeneic lymphocytes in primary mixed lymphocyte kidney culture (MLKC) (maximum of 8110 +/- 5015 vs. 3966 +/- 4050 counts/min on day 8), which was further increased by addition of IL-1. This proliferation never approached that induced by peripheral blood mononuclear stimulator cells (maximum of 40,325 +/- 10,694 counts/min on day 5), and addition of HK cells to mixed lymphocyte culture inhibited proliferation. There was no difference in lysis of IFN-gamma-treated or untreated HK-cell targets by "specific" cytotoxic effector cells produced in mixed lymphocyte culture using stimulator lymphocytes from the kidney cell donor (49.4 +/- 20% vs. 50.4 +/- 26% specific release in CML). Lysis by 3rd-party cytotoxic effectors produced in MLC using stimulator lymphocytes unrelated to the kidney-cell donor was greater for untreated HK cells (27.4 +/- 20%) than for IFN-gamma-treated HK targets (7.6 +/- 6%, P less than 0.001). IFN-gamma-activated naive mononuclear leukocytes lysed untreated HK targets but not IFN-gamma-pretreated targets, and this nonspecific cytotoxicity was mediated by lymphocyte- but not monocyte-enriched cell populations. HK cells are therefore poor stimulators of alloproliferation even when they express increased HLA antigen. They are lysed by both specific and nonspecific effector cells, and exposure to IFN-gamma makes them less vulnerable to nonspecific cytotoxicity and by inference, more vulnerable to specific cytotoxicity.

Methods for quantitating HLA gene product expression in the liver during hepatitis B virus infection.

HLA antigens play an important role in the immunological responses to transplanted organs and in tumor surveillance and antiviral immunity. In several liver diseases qualitative and quantitative changes in the HLA gene product expression can be found on hepatocytes, bile duct epithelium and sinusoidal lining cells and these changes may affect the efficacy of the immune system in recognizing an exogenous antigen. In this paper we describe methods for quantitating the changes in HLA antigen expression occurring in the liver during various phases of hepatitis B virus infection and the way in which we have attempted to identify possible mechanisms leading to chronicity.

HLA antigens in ocular tissues. I. In vivo expression in human eyes.

The eye is a common site for autoimmune inflammatory diseases, many of which are linked to HLA antigens. The role of these HLA phenotypes in the disease process is presently unknown. In view of the importance of HLA antigens to immune responses, a knowledge of the distribution of HLA antigens in ocular tissues may aid in our understanding of the role of these antigens in disease production or susceptibility. Apart from the cornea, the expression of HLA antigens in human ocular tissues has not been thoroughly investigated. In this study we examined the in vivo expression of HLA antigens in postmortem human eyes using immunohistochemical techniques. The majority of ocular cells were found not to express class I or class II HLA antigens, with the exception of the blood vessel endothelium, which was uniformly class I-positive. The significance of these results is discussed in relation to ocular immunity.

Variation of Class I HLA Antigen Expression Among Platelet Density Cohorts: A Possible Index of Platelet Age?

Platelet alloantigens and other surface markers were studied in platelet cohorts of different mean density, using monoclonal and polyclonal probes. High density (HD) platelets expressed 12% more P1A1 molecules (46,942) than low density (LD) platelets (41,892). However, LD platelets carried 42% more HLA-A2 molecules (6,267 +/- 184) than HD platelets (4,406 +/- 232) (P less than .01) and 55% more class I HLA antigens (17,034 +/- 2,062 v 11,007 +/- 2,190) (P = .05). The platelet subpopulations did not differ in their content of glycoprotein (GP)IIb/IIIa complex or Baka antigen. The difference in expression of class I HLA antigens on HD and LD platelets is consistent with two possibilities: either class I HLA molecules are acquired from plasma or they are released into plasma as platelets age in circulation. Accordingly, class I HLA molecules may provide a useful marker of platelet age.

Variation of class I HLA antigen expression among platelet density cohorts: a possible index of platelet age?

Platelet alloantigens and other surface markers were studied in platelet cohorts of different mean density, using monoclonal and polyclonal probes. High density (HD) platelets expressed 12% more P1A1 molecules (46,942) than low density (LD) platelets (41,892). However, LD platelets carried 42% more HLA-A2 molecules (6,267 +/- 184) than HD platelets (4,406 +/- 232) (P less than .01) and 55% more class I HLA antigens (17,034 +/- 2,062 v 11,007 +/- 2,190) (P = .05). The platelet subpopulations did not differ in their content of glycoprotein (GP)IIb/IIIa complex or Baka antigen. The difference in expression of class I HLA antigens on HD and LD platelets is consistent with two possibilities: either class I HLA molecules are acquired from plasma or they are released into plasma as platelets age in circulation. Accordingly, class I HLA molecules may provide a useful marker of platelet age.

HLA antigen expression and cellular infiltrate analysis in rejected human liver grafts

HLA antigen expression and cellular infiltrate analysis in rejected human liver grafts

HLA antigen expression and induction by γ-interferon in cultured human trophoblasts

The expression and regulation of HLA antigens were examined in isolated human trophoblasts. Immunocytochemical studies that used monoclonal antibodies against class I (HLA-A, B, and C) antigens revealed that both cytotrophoblasts and syncytiotrophoblasts can express HLA heavy chains and beta 2-microglobulin. Expression of these antigens increased with time in culture. The addition of recombinant gamma-interferon (1000 U/ml) to the cultures significantly increased cellular staining for these antigens over controls throughout the 72-hour time course studied. In addition, we noted that gene expression for HLA class I heavy chain was also markedly augmented by the addition of gamma-interferon. Expression of class II (HLA-DR) antigens was not detected in any of the experiments. These results suggest that during in vitro differentiation, cytotrophoblasts can express class I HLA antigens and the genes controlling their production can be regulated. Alterations in the expression or suppression of these antigens during pregnancy could be responsible for some pregnancy complications.