Human leukocyte antigen association with azathioprine-induced drug hypersensitivity reactions in patients with anti-neutrophil cytoplasmic antibody associated vasculitis

Azathioprine (AZA) drug hypersensitivity reaction (DHR) is an uncommon yet potentially lethal condition that often goes unrecognised in patients with anti-Neutrophil Cytoplasmic Antibody (ANCA) associated vasculitis (AAV). We conducted a retrospective review of AAV patients on AZA maintenance therapy (N = 35). Participants were categorised into those who had experienced AZA-DHR (N = 15) and those who were AZA-tolerant (N = 20). Human leukocyte antigen (HLA) typing was performed in both groups. The primary endpoint was identification of a HLA gene association with AZA-DHR in the context of AAV. HLA-C*06:02, was solely expressed in AZA-DHR patients (33.3 %), whilst no patient who tolerated AZA carried this allele (0.0 %). This yielded a positive predictive value of 100 % for HLA-C*06:02 in predicting AZA-DHR in AAV patients, negative predictive value of 66.7 %, sensitivity of 33.3 % and specificity of 100 %. HLA-C*06:02 may predict the development of AZA-DHR in patients with AAV and inform safer therapeutic choice.

[Current and future care for diabetes in children: from insulin to immunotherapy]

Diabetes type I (DTI) is an autoimmune disease characterized by a progressive destruction of the insulin producing beta cells of the pancreas that requires insulin substitution therapy. Recent epidemiological data show an annual increase of the incidence of DTI of 3.9%. Children with new onset diabetes typically present with polyuria, polydipsia and weight loss. As of today no cure for DTI exists. However new therapeutic immunomodulary approaches are under investigation. In the meantime adherence to insulin therapy is mandatory to achieve near physiological glucose levels. Monogenic forms of diabetes remain rare in children, but their diagnosis is important in order to propose a specific treatment. A critical period for the diabetic patient is the transition from pediatric to adult care.

The Effect of Antithymocyte Globulin on Anti–Human Leukocyte Antigen Antibody Detection Assays

BACKGROUND

We evaluated the effect of antithymocyte globulin (ATG) on anti-human leukocyte antigen (HLA) antibody assays.

METHODS

We tested sera from six in vivo ATG-treated kidney transplant patients after measuring serum concentrations, as well as six nonsensitized sera with ATG added in vitro. T- and B-cell complement-dependent cytotoxicity (CDC), flow cytometric (FXM), and solid-phase HLA class I and II assays based on antigen-coated microspheres and enzyme-linked immunosorbent assay (ELISA) were studied. Sera were then retested after treatment to remove ATG.

RESULTS

We found that ATG affects test results differently depending on whether sera is obtained from in vivo treated patients or added in vitro. In vitro treated sera produced ATG concentration-dependent positive results for T/B CDC, FXM, and flow bead testing for HLA I/II, while the ELISA-based assay was unaffected. In vivo treated sera from ATG-treated patients produced positive test results for T CDC and T/B FXM, while the B-cell CDC crossmatch remained negative. Solid phase assays were minimally affected using in vivo treated sera. After ATG extraction, all tests became negative.

CONCLUSION

We conclude that ATG produces positive results in anti-HLA antibody testing, and treatment to remove ATG abolishes this effect. This treatment allows ATG-treated patients to be monitored for anti-HLA antibodies.

Modulation of HLA-G expression

Recent studies demonstrated that HLA-G transcription is in some cells silenced by epigenetic mechanisms as DNA methylation and histone modification. Accordingly HLA-G gene transcriptions can be activated in such cells by demethylating agent or by inhibitors of histone deacetylation. In addition to epigenetic alterations HLA-G gene transcription can be activated by stress. In the present study these aspects of HLA-G expression are re-examined and a new inhibitor of histone deacetylation (valproic acid) and hypoxia mimetic chemical (CoCl2) are included. The highest activation of HLA-G transcription was achieved by treatment of choriocarcinoma JAR and lymphoblastoid RAJI cell lines with demethylating agent 5-aza-2 - deoxycytidine. Treatment of JAR and RAJI cells with histone deacetylase inhibitors (sodium butyrate and valproic acid) also enhanced HLA-G transcription. Nevertheless this increase in HLA-G expression was low as compared with activation by 5-aza-2 - deoxycytidine. The hypoxia mimetic agents (desferrioxamine or CoCl2) had no detectable effect on HLA-G gene transcription in examined cells. Relatively high increase of HLA-G transcription was detected in JAR and RAJI cells exposed to heat shock treatment. Interestingly heat shock induced high expression of HLA-G6 transcript in JAR cells. Heat shock treatment had no effect on alternative splicing of constitutively expressed HLA-G mRNA in choriocarcinoma cell line JEG-3. HLA-G1 protein expression was induced in JAR and RAJI cell lines by 5-aza-2 - deoxycytidine. In agreement with the differences in the levels of HLA-G transcripts JAR cells express more of HLA-G1 protein than RAJI cells.

The effects of gp100 and tyrosinase peptide vaccinations on nevi in melanoma patients

BACKGROUND

A new approach to prevent disease recurrence in high-risk melanoma patients involves immunization with gp100 and tyrosinase peptides. This is the first study to examine the effects of such treatments on nevi.

DESIGN

We studied biopsies of 'clinically atypical' nevi from 10 patients before and after peptide vaccination. All had a cutaneous melanoma measuring at least 1.5 mm in depth, satellite metastases, or at least one positive lymph node. We performed immunohistochemical stains for CD3, CD4, CD8, MHC-I, MHC-II, CD1a, HMB-45, MART-1, tyrosinase, bcl-2, p53, and Ki-67 (mib-1).

RESULTS

Immunohistochemistry showed no differences in staining due to vaccination in either the immunologic or melanocytic markers. However, there was a significant increase in both p53 and bcl-2 staining, and a trend toward decreased Ki-67 staining, in the nevi post-treatment.

DISCUSSION

The primary goal of peptide vaccinations with gp100 and tyrosinase is to activate melanoma-specific T cells in order to prevent melanoma recurrence. Nevi were studied in order to assess the effects on benign melanocytes. No significant changes in lymphocytes, langerhans cells, expression of MHC antigens, or melanocytic markers were found. The increase in p53 and bcl-2 raises the possibility that vaccination with melanocytic antigens stimulates a response in benign melanocytes.

Induction of HLA-G expression in a melanoma cell line OCM-1A following the treatment with 5-aza-2′-deoxycytidine

The non-classical HLA class I antigen HLA-G is an immune modulator which inhibits the functions of T cells, NK cells, and the Dendritic cells (DC). As a result, HLA-G expression in malignant cells may provide them with a mechanism to escape the immune surveillance. In melanoma, HLA-G antigen expression has been found in 30% of surgically removed lesions but in less than 1% of established cell lines. One possible mechanism underlying the differential HLA-G expression in vivo and in vitro is that the HLA-G gene is epigenetically repressed in melanoma cells in vitro. To test this hypothesis, we treated the HLA-G negative melanoma cell line OCM-1A with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine (5-AC) and analyzed whether HLA-G expression can be restored. Our data strongly suggest that HLA-G is silenced as a result of CpG hypermethylation within a 5' regulatory region encompassing 220 bp upstream of the start codon. After treatment, HLA-G mRNA expression was dramatically increased. Western blot and flow cytometry showed that HLA-G protein was induced. Interestingly, HLA-G cell surface expression on the 5-AC treated OCM-1A cells is much less than that on the HLA-G positive JEG-3 cells while a similar amount of total HLA-G was observed. Possible mechanisms for the difference were analyzed in the study such as cell cold-treatment, peptide loading and antigen processing machinery components (APM) as well as beta2 microglobulin (beta2-m) expression. Data revealed that the APM component calreticulin might be involved in the lower HLA-G surface expression on OCM-1A cells. Taken together, our results indicated that DNA methylation is an important epigenetic mechanism by which HLA-G antigen expression is modulated in melanoma cells in vitro. Furthermore, to the first time, we hypothesized that the deficiency of calreticulin might be involved in the low HLA-G surface expression on the 5-AC treated OCM-1A cells.

Immunomodulatory effects of fetal and adult mesenchymal stem cells

Mesenchymal stem cells (MSC) derived from adult BM or fetal liver form several mesenchymal tissues after appropriate stimulation. Reports indicate that MSC have unique immunologic properties, making them ideal for cellular therapy. MSC are not immunogenic, they do not stimulate alloreactivity, and they escape lysis by cytotoxic T-cells and natural killer (NK)-cells. Thus, MSC may be transplantable between HLA-mismatched individuals without the need for host immunosuppression. Furthermore, adult MSC appear to be immunosuppressive as they reduce alloreactivity and the formation of cytotoxic lymphocytes in vitro. In vivo, adult MSC prolong the time to rejection of mis-matched skin grafts in baboons. The immunosuppressive properties of first trimester fetal MSC are less pronounced, but inducible with IFNgamma. These findings imply a potential role for MSC, not only in the repair of damaged tissues, but also in the manipulation of immune responses.

Mild acid treatment induces cross-reactivity of 4H84 monoclonal antibody specific to nonclassical HLA-G antigen with classical HLA class I molecules

Mild acid treatment by releasing beta(2)m and antigenic peptides leaves human leukocyte antigen (HLA) class I free heavy chains attached to the cell surface. Acid treatment thus allows detection of the cell surface class I antigens by monoclonal antibodies (mAbs) specific to HLA-free heavy chains. We found that acid treatment also enables detection of the cell surface non-classical HLA-G class I antigen with mAbs specific for HLA-G free heavy chains, including 4H84 mAb recognizing all isoforms. Furthermore, we found that 4H84 mAb, but not other mAbs specific to HLA-G free heavy chains, binds to the surface of 8 out of 16 acid-treated leukemia cell lines. Nevertheless, HLA-G antigen is not present in any of these leukemia cells. This was demonstrated by failure to detect any antigen with 4H84 mAb in immunoblotting as well as by inability to detect HLA-G mRNA by RT-PCR. The antigen recognized by 4H84 mAb in some acid treated leukemia cells was identified by immunoprecipitation as a 45 kDa protein. A number of observations indicate that 45 kDa proteins are none other than classical class I heavy chains. Acid treatment thus induces the ability of the 4H84 mAb to recognize some classical HLA class I molecules. Remarkably, 4H84 determinant on HLA-G is linear but corresponding determinant present on some partially folded classical HLA class I free heavy chains is conformational. In view of the unexpected cross-reactivity, detection of HLA-G with this mAb must be carefully evaluated to avoid false detection.

Brain derived neurotrophic factor does not act on adult human cerebral endothelial cells

Brain derived neurotrophic factor (BDNF), known to promote survival of neurons, has recently been involved in the regulation of endothelial cells and was shown to possess immunoregulatory properties. We therefore asked whether BDNF has immunoregulating effects in human cerebral endothelial cells (HCEC). Adult HCEC expressed vascular cell adhesion molecule-1 and HLA class II following stimulation with tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma, respectively, but not after BDNF treatment. Addition of BDNF did not modulate the effects of TNF-alpha and IFN-gamma on HCEC, including TNF-alpha induced interleukin-8. Fluorescent activated cell sorting, RT-PCR, and immunohistochemistry indicated that HCEC do not express the trkB or p75 receptors involved in BDNF signaling. These results demonstrate that adult HCEC are not a likely target for BDNF. Novel factors regulating HCEC remain to be identified.

Human natural killer cell function and receptors

Recent years have witnessed major progress in our understanding of the molecular mechanisms regulating natural killer cell (NK cell) function. These advances stem primarily from the discovery of a number of receptors specific for major histocompatibility complex (MHC) class I and, more recently, of the activating receptors and coreceptors responsible for natural cytotoxicity. Important studies performed over the past year have allowed us to define the evolution of the MHC-specific inhibitory receptors by comparative analysis in different species. The roles of the 'activating natural cytotoxicity receptors', NKG2D and certain coreceptors in the lysis of different tumors have been defined in detail. The mechanism by which the 2B4 coreceptor renders patients with X-linked lymphoproliferative disease unable to control Epstein-Barr virus has been elucidated. Inhibitory receptors identified in NK cells may also be expressed by normal and leukemic myeloid cells, in which they can block cell proliferation and survival. It has also become clear that viruses such as cytomegalovirus have evolved strategies to interfere with NK-cell function to protect themselves from NK-mediated attack.

Differential inhibitory effects of intravenous immunoglobulin preparations on HLA-alloantibodies in vitro

BACKGROUND

Treatment of allosensitized patients with intravenously administered pooled immunoglobulin preparations (IVIG) may lead to a long-lasting reduction of anti-HLA alloantibody titers. An inhibitory response of IVIG preparations on lymphocytotoxicity is suggested to depend on IgG and to predict a successful reduction of anti-HLA alloantibodies upon the administration of high-dose IVIG in vivo.

METHODS

In this study, we evaluated different IVIG preparations for their in vitro inhibitory capacity on lymphocytotoxicity and binding of anti-HLA alloantibodies to purified HLA antigens. For that purpose sera from 24 highly sensitized patients awaiting kidney transplantation and serological HLA testing reagents were used. Panel-reactive antibody (PRA) determinations using standard complement-dependent cytotoxicity testing and anti-HLA alloantibody determination by ELISA were carried out in the presence and absence of 50% (v/v) IVIG.

RESULTS

The addition of IgG-containing IVIG preparations gave only a moderate inhibitory response judging from the average decrease of PRA levels (absolute DeltaPRA range: -2% to 16%), whereas the largest inhibition of lymphocytotoxicity was seen after the addition of IgM/IgA-containing IVIG preparations (absolute DeltaPRA range: 19% to 44%). For both IgG and IgM/IgA-containing IVIG preparations, the reduction of lymphocytotoxicity occurred in a dose-dependent fashion without a preference for particular anti-HLA class I antibody specificities. Significantly lower inhibitory effects on anti-HLA antibody reactivity were observed when the effects of IVIG preparations were monitored by ELISA (absolute DeltaPRA range: 7% to 22%).

CONCLUSIONS

Our data suggest that the immunomodulatory capacity is largely caused by the IgM/IgA fraction of IVIG when analyzed by lymphocytotoxicity. The different effect on ELISA versus complement-dependent cytotoxicity testing suggests that interactions of IVIG with complement rather than anti-idiotypic antibodies may contribute to the inhibitory effects of IVIG in vitro.

Expression analysis of classic and non-classic HLA molecules before interferon alfa-2b treatment of melanoma

Individual predictive clinical, immunological, or molecular features for definition of patients with lymph-node-positive melanoma who do not benefit from adjuvant postsurgery high-dose interferon alpha treatment are lacking. Expression analysis of classic and non-classic HLA molecules on melanoma cells metastatic to the locoregional lymph node may help select these patients before treatment.

Can the expression of histocompatibility antigen be changed by lithium?

OBJECTIVES

This study attempted to determine whether human leukocyte antigen (HLA) type changes would be caused by lithium.

METHODS

A total of 15 patients were chosen as subjects (4 males, 11 females) and completed tests in class I. Eight of the 15 patients completed tests in class II. Their mean age was 27 +/- 7 years. For an average of 51 +/- 17 days, lithium, 600-1,200 mg/day (mean daily dose: 920 +/- 211 mg) was administered for the HLA testing and then compared with the HLA type prior to the time the drug was administered. Class I type test was performed according to the Terasaki microcytotoxicity method and class II type by the Erlich polymerase chain reaction method.

RESULTS

Of the 15 subjects, 11 had changes in HLA-A, B, C types and two of the eight subjects had changes in HLA DR type.

CONCLUSION

Lithium, in the therapeutic dose, is considered to bring about changes in HLA expressions in as short a time period as 2 months.

The differentiating effect of retinoic acid and vincristine on acute myeloid leukemia

We have shown previously that granulocytic maturation and differentiation occurred when HL-60 cells and leukemia cells from a patient with acute promyelocytic leukemia (APL) were exposed to all-trans retinoic acid (ATRA) after treatment with a noncytotoxic concentration of vincristine (VCR), suggesting that VCR might have synergistic action with ATRA in the treatment of APL. Leukemic cells obtained from 24 patients with AML were exposed to 20 nM VCR for 1 h, followed by 1 microM ATRA for 6 days. Changes in the expression of myeloid leukocyte antigens were observed using flow cytometry. Differentiation phenotype as determined by the decrease or increase in maturation cell marker was observed in three samples treated with VCR alone, four samples treated with RA alone, and two samples treated with the combination of VCR and RA. The results suggest that treatment using VCR and ATRA may be effective in the differentiation therapy of AML.

[Tylosin-specific proliferation in vitro of the peripheral blood mononuclear cells in occupational tylosin allergy]

Tylosin-specific lymphocyte proliferation in vitro and its restriction of HLA class II antigens have been investigated in 21 allergic workers exposed to tylosin. Nine workers from tylosin industry without allergic symptoms and five nonexposed nonallergic subjects served as controls. The results showed a significantly higher lymphocyte proliferative response to tylosin in allergic workers compared to control groups. Lymphocyte proliferation was observed in five workers with allergic complaints but negative skin tests. The tylosin concentration leading to maximal proliferative response varied from 10 to 1000 micrograms/ml among individuals. Six from seven workers with maximal response to the lowest concentration of tylosin carried HLA-DQ2 antigen. Lymphocyte from most control subjects did not respond in vitro to tylosin. Weak proliferative response to tylosin was observed in two workers without clinical symptoms of allergy. No association was found between lymphocyte reactivity to PHA and tylosin in the three studied groups. In conclusion, tylosin leads to a specific activation of T lymphocytes in occupationally sensitized workers. Possibly, the T cell recognition of the hapten/protein complex is restricted by HLA-DQ2 antigen in tylosin occupational allergy. Lymphocyte stimulation test can be used for the diagnosis of tylosin occupational allergy, as well as for the detection of latently sensitized workers.

Cis-trans complementation of DQA1-DQB1 genes are modulated by DQ alleles: an immunogenetics analysis of DQ association with the down-regulatory function of CD8 cells in trichosanthin-induced immunosuppression

The initiation of a CD8 cell-mediated pathway (M+) was adopted as a phenotypic trait to analyse genetic predisposition in trichosanthin (Tk)-induced immuno-suppression. Tk is a natural protein antigen with 247 amino acid residues. Based on DNA typing for DR, DQ, DP and TAP genes, data in this paper indicate that only DQ genes were primarily involved and that the alleles DQA1*0501 and DQB1*0201 were strongly associated with the M+ phenotype in cis (on DR3 haplotype) or trans (on DR5/DR7 heterozygotes) complementation. This is consistent with our observation that only the DQ-positive cells were capable of expanding after being co-cultured with Tk for 96 h. Two points of interest were noted. (1) The susceptible haplotype DRB1*0301-DQA1*0501-DQB1*0201 showed an association with the M+ phenotype only if combined with DRB1*04-, DRB1*08-, or DRB1*09-related haplotypes. When co-presented with DRB1*11-, DRB1*15-, DRB1*07-related haplotypes, however, no cis complementation could be detected. A detailed analysis of the association patterns indicated that the DQB1 locus of the non-susceptible haplotypes was the main factor for up- or down-modulation. (2) For M+ phenotype-related trans complementation in Tk-induced suppression, it was found that not only DQA1*0501-DQB1*0201 (DR5/7) alleles, but also associated DQA1*0301-DQB1*0201 (DR4/7, 9/7) alleles, were involved. The allele DQB1*0201 was not associated with the DQA1 alleles in DRB1*01-, DRB1*15-, DRB1*13-, DRB1*07-related haplotypes. The results obtained indicate that there are some additional genetic factors involved in the functional expression of cis and trans complementation of DQA1 and DQB1 genes, among which the DQ alleles play a critical role as self-regulators.

Relationship between antibody-dependent cell-mediated cytotoxicity due to anti-HTLV-1 and negative signal of major histocompatibility complex class I antigens on adult T-cell leukemia cell lines

Natural killer (NK) cells possess two types of cytotoxic activity: natural killer cytotoxicity (NKC) and antibody-dependent cell-mediated cytotoxicity (ADCC). The NKC is regulated by the negative signal of the NK receptor, which recognizes major histocompatibility complex (MHC) class I antigens. However, it is not known whether or not the negative signal influences the ADCC. In this study, the relationship of the ADCC and negative signal was investigated. As target cells, adult T-cell leukemia (ATL) cell lines were used. When the target cells were treated with an anti-human T-lymphotropic virus type-1 (anti-HTLV-1) antibody, they were killed by the NK cells by means of the ADCC (ADCC/anti-HTLV-1). The killing levels were parallel with the cell surface HTLV-1 antigenicity. However, when these cells lines were treated with an anti-HLA, the ADCC (ADCC/anti-HLA) showed inverse correlation with the HLA antigenicity. Furthermore, when HLA polymorphic and monomorphic determinants of these target cells were blocked by F(ab')2 fragments of the anti-HLA and W6/32, the ADCC/anti-HLA was enhanced, but the ADCC/anti-HTLV-1 was not enhanced. These results suggest that the ADCC/anti-HLA may have an intimate relationship with the MHC class I antigens. The ADCC/anti-HLA may be suppressed by the negative signal. On the other hand, the ADCC/anti-HTLV-1 may have no relationship with the class I antigens and the negative signal may have no influence against the ADCC/anti-HTLV-1. The biological mechanism of this difference remains to be investigated.

Human leukocyte antigen system in clozapine-induced agranulocytosis

Forty-three schizophrenic patients participating in this study were serotyped for human leukocyte antigens (HLA-A, -B, -C, -DR, -DQ antigens). Thirty-six of them were hospitalised in two state mental hospitals and 7 in our general hospital, psychiatric unit. The patients from our unit were typed for HLA before commencing clozapine treatment whereas the patients from state hospitals were typed after commencing treatment. Three out of 43 patients developed agranulocytosis. One had a combination of both 'high-risk' haplotypes (HLA-B16(38,39), DR4, DQ3 and HLA-DR2, DQ1), another had HLA-DR2, DQ1, whereas the last had a totally different haplotype. Between non-agranulocytic patients 1 was found to carry the HLA-B16(38,39), DR4, DQ3 haplotype and 14 (out of 40) had the HLA-DR2, DQ1. Taking into account other factors supposed to be involved (a noxious metabolite, and the presence of a humoral cytotoxic factor) we must admit that despite the finding of a high-risk haplotype in Jewish populations there are other aspects of this question awaiting clarification.

Effects of interferon-alpha treatment on neutrophil oxidative metabolism, lymphocyte proliferation and monocyte HLA class I antigen expression in patients with chronic hepatitis C

Polymorphonuclear cell (PMN) oxidative metabolism, lymphocyte polyclonal proliferation and monocyte HLA class I antigen expression were evaluated at different intervals of time in patients with chronic hepatitis C (CH-C) subjected to a 6 month interferon alpha (IFN-alpha) treatment and divided into Responder ('R') and Nonresponder ('NR') subsets according to clinical outcome. Before therapy, all subjects exhibited multiple immune alterations even if to a different extent between 'R' and 'NR' subsets: an elevated superoxide anion (O2-) generation by suspended PMN, a failure to further increase neutrophil oxidative responsiveness under adherence conditions, an augmented phytohaemagglutin-induced lymphocyte proliferative capacity and an enhanced HLA class I antigen expression on CD14+ cells. IFN-alpha administration gave rise to a modulation of oxidative response in 'R' group only, since these individuals displayed an O2- release by suspended and adherent PMN which fell within normal values. At the same time, a decrease of lymphocyte proliferation occurred in both groups of patients during IFN-alpha therapy, even if it reached statistical significance in 'R' group only. Finally, a more marked difference between 'R' and 'NR' individuals was noted in terms of HLA class I antigen induction on CD14+ cells at the end of therapy, as a consequence of a reduced expression of these structures in 'NR' subjects. Altogether, these findings suggest the occurrence of a strict relationship between immunoresponsiveness and IFN-alpha induced therapeutical effects in CH-C patients.

Influence of anticoagulants on the level of soluble HLA class I and class II antigens measured in blood samples

The existence of soluble forms of HLA class I and class II antigens in human serum is well established and altered concentrations of these serum proteins have been described to be associated with various diseases. Since soluble HLA antigens (sHLA) can be measured both in serum and plasma samples, we investigated whether anticoagulant treatment influences the determined levels of soluble HLA class I (sHLA-I) or soluble HLA-DR (sHLA-DR). Analyzing paired samples of serum and plasma of 40 healthy individuals we found significantly lower serum levels of sHLA-DR (0.31 +/- 0.15 ng/ml) compared to EDTA plasma levels (0.58 +/- 0.20 ng/ml). By contrast, serum levels of sHLA-I (0.89 +/- 0.74 micrograms/ml) were only slightly lower than EDTA plasma values (0.95 +/- 0.86 micrograms/ml), a situation similar to that of sIL-2R and sCD4 levels. Further experiments intended to clarify the reasons of the reduced sHLA-DR serum levels revealed that (i) the blood storage time before centrifugation did not influence the sHLA-DR level, (ii) treatment of serum with anticoagulant did not augment the measured sHLA-DR concentration, and (iii) the recovery of spiked sHLA-DR was significantly lower when added to native blood than to serum or anticoagulant-treated blood. These results suggest that sHLA-DR is partly removed by the process of blood clotting thus resulting in diminished sHLA-DR serum levels.

Cis-diamminedichloroplatinum(II) augments expression of tumor-associated antigens on human gastric cancer cell line KATO-3 and increases susceptibility and binding of tumor cells to various cytotoxic effector cells

Previous studies have demonstrated the immunomodulatory effects of cisplatin under certain conditions. The present study was designed to clarify whether cisplatin modulates the expression of surface antigens, especially human leukocyte antigen (HLA), on human tumor cell lines and/or augments the susceptibility and binding of tumor cells to cytotoxic effector cells. A human gastric cancer cell line, KATO-3, was employed. The expression of HLA and other tumor-associated antigens was analyzed by flow cytometry using FITC-conjugated monoclonal antibodies. The cytotoxicity of effector cells was determined by 51Cr release assay. The expression of HLA class I antigen, beta2-microglobulin, leukocyte function-associated antigen-1, and AC-81 adenocarcinoma-associated antigen on KATO-3 increased after exposure to cisplatin at 10 micrograms/ml for 3-6 hr; augmentation of HLA class I subtypes -B2 and -B27 was particularly prominent. Furthermore, the susceptibility and binding of KATO-3 to both lymphokine-activated killer cells and KATO-3-specific cytotoxic T lymphocytes significantly increased after cisplatin treatment. Cisplatin may modulate the expression of tumor-associated antigens on some human tumor cells. Tumor regression by cisplatin administration may depend on its direct cytotoxicity as well as on its modulating effects on the expression of tumor-associated antigens, subsequently leading to the activation of the immune surveillance system against the tumor.

Homocysteine modification of HLA antigens and its immunological consequences

Homocysteine-treated cells can be specifically lysed by cytotoxic T lymphocytes (CTL) identifiable in patients with ankylosing spondylitis and reactive arthritis. Sensitization of target cells involves disulfide bonding and the interaction between homocysteine and HLA antigens occurs in a pre-Golgi compartment in the cells. Salmonella-infected B cells are also lysed by homocysteine-specific CTL, suggesting that intracellular invading microorganisms may provide homocysteine which would gain access to the newly synthesized intracellular HLA molecules and modify them inside the cells. Two different mechanisms for homocysteine modification of HLA antigens are proposed: homocysteine could bind directly to the unpaired cysteine residues in HLA antigens, or it could bind indirectly to HLA antigens through cysteine-containing peptides bound to them. Thus, HLA antigens containing unpaired cysteine residues (e.g. HLA B27) could be modified by homocysteine directly or indirectly, while HLA antigens without unpaired cysteine residues (e.g. HLA A68) could only be modified indirectly. The results are discussed in relation to the potential involvement of homocysteine-specific CTL in ankylosing spondylitis and reactive arthritis, both of which are related to bacterial infections, associated with HLA B27, and considered to be autoimmune diseases.

HLA typing in chronic type B, D and C hepatitis

AIMS

We aimed to test the hypothesis that susceptibility to chronic HBV, HDV and HCV infections or their pathology is influenced by host genetic factors.

METHODS

The Human Leukocyte Antigens (HLA) (A, B, DR and DQ) were determined by microlymphocytotoxicity assay in patients with chronic C (n = 117), B (n = 97) or D (n = 27) hepatitis and their frequencies were compared with those of 489 healthy controls.

RESULTS

No statistically significant association was found between any HLA antigen and chronic B or D hepatitis. A significantly higher frequency of HLA-B14 was observed in patients with chronic persistent or active C hepatitis (16.7% of 90 versus 5.9% of 489, chi(2) = 10.9, pc < 0.05, Relative Risk = 3.17, Etiological Fraction = 0.11). The frequency of HLA-DR5 was lower in HCV positive patients (24.8%) than in controls (45%, chi(2) = 15.1, pc < 0.005, RR = 0.4, EF = -0.37).

CONCLUSIONS

No correlation could be observed between clearance of HBV or HDV and HLA phenotype. Immunogenetic factors may have a role in determining susceptibility to chronic HCV hepatitis, and in Italian patients HLA-DR5 is a protective factor.

Acid treatment of lymphocytes selectively decreases the expression of HLA class I antigens: a method to confirm that a positive clinical crossmatch test was due to class I antibodies

A rapid and reliable method for eliminating HLA class I antigens from the surface of lymphocytes without damaging the cells is described. Lymphocytes were exposed to an acid solution (pH 3.0) which selectively destroys the antigenicity of HLA class I antigens. Alloantisera containing multispecific HLA class I antibodies reacted with phosphate-buffered saline (PBS)-treated, but not with acid-treated, lymphocytes. Specificity controls included: antibodies against HLA class II antigens and CD3, CD4, CD8; markers expressed on T cells and CD19, CD23; markers expressed on B cells. No change in lymphocyte reactivity to any of these surface antigens or to autoantibodies was observed. The viability of acid-treated lymphocytes was regularly around 90%. We propose that acid-treated lymphocytes are suitable targets for determination of the sole presence of class I antibodies in crossmatch sera of patients awaiting organ transplants.

Kinetically coordinated induction of TAP1 and HLA class I by IFN-gamma: the rapid induction of TAP1 by IFN-gamma is mediated by Stat1 alpha

Transporter associated with Ag processing-1 (TAP1) is induced by IFN-gamma more rapidly than is HLA class I. Kinetic analysis of transfectants reveals that IFN-gamma activates the TAP1 promoter more rapidly than the HLA-B7 class I promoter. A gamma-activating sequence (GAS) in the TAP1 promoter is necessary for the rapid induction by IFN-gamma. Two overlapping IFN consensus sequences contribute to the constitutive and TNF-induced expression of TAP1 but are not necessary for the IFN-gamma response. Moreover, IFN-gamma activates the GAS-binding protein Stat1 alpha much more rapidly than it induces the IFN consensus sequence-binding protein IRF-1, which mediates the response of the HLA-B7 class I promoter. We conclude that IFN-gamma uses different transcription factors to regulate the sequence of appearance of these interacting gene products.

Interleukin 12 unmasks HLA class I differences during mixed lymphocyte reaction induced interferon gamma production

We investigated the genetic control of IFN-gamma release during MLR and its relationship with TNF-alpha and IL-12. Blocking experiments demonstrated the IFN-gamma dependence of TNF-alpha production and the significant contribution of IL-12 to IFN-gamma secretion. We studied informative pairs allowing the evaluation of the relative importance of HLA class I and class II antigens. Maximal IFN-gamma secretion allowing discrimination between fully HLA different and identical subjects required 5 days. In class I different but DRB1 identical pairs, a moderate but discriminant IFN-gamma release was found. Exogenous IL-12 addition after 24 hours of preactivation by MLR resulted in a marked enhancement of IFN-gamma production at day 2. In pairs differing only by class I antigens, the discriminating capacity was significantly increased as compared to values obtained in absence of IL-12 at day 2 (p < 0.004) and at day 5 (p < 0.004). The crucial role of class I antigens on IFN-gamma release was further substantiated by the blocking action of the W6/32 mAb directed against a monomorphic epitope common to all HLA-A, -B, and -C antigens. We conclude that IFN-gamma production during MLR is under the control of class I antigens. Furthermore, exogenous IL-12 strongly amplifies their influence.

Alterations of cell surface antigens induced by placental isoform of ferritin in human carcinoma cell lines

AIM

the ability of the breast cancer-associated placental acid isoform of ferritin (p43-PLF) to modulate cell surface expression of HLA, CD59 (protectin) and CD66 antigen (adhesion antigen related to CEA) was examined.

METHODS

the expression of these antigens in human breast carcinoma cell lines BT-20, T47D and MDA-MB-468 was determined with the aid of flow cytometry and monoclonal antibodies.

RESULTS

PLF induced a transient up-regulation followed by a down regulation of cell surface protectin (CD59 antigen) on the cell surface of T47D and to a lesser extent, BT-20 human breast carcinoma cell lines. Furthermore, PLF down-regulated cell surface expression of CEA-related CD66 antigen on both these cell lines. No PLF-induced alterations of protectin, CD66 antigen and HLA class I antigen were found on the MDA-MB-468 breast cancer cell line.

CONCLUSIONS

breast cancer-associated p43 induces alterations of the expression of cell surface molecules in breast cancer cells which could have an effect on the modulation of cancer cell adhesive interactions.

Organic solvent exposure may increase the risk of glomerular nephropathies with chronic renal failure

BACKGROUND

Several studies have suggested that exposure to organic solvents is associated with glomerular nephropathies (GN), but this relationship remains controversial.

METHODS

A case-control study of 298 biopsy-proven cases and 298 hospital controls, matched for year of birth, sex, origin, and place of residence, was conducted between 1989 and 1991 in five hospitals in the Paris area: 82 cases of membranous glomerulopathy were included; 100, nephrotic syndrome with either minimal change nephropathy or focal and segmental hyalinosis (MCN/FSH); and 116, IgA nephropathy (IgA N). Subjects were interviewed about their lifelong occupational and non-occupational activities. A 'blind' assessment of type, level, and duration of solvent exposure was carried out by two industrial hygienists. Human leucocyte antigen (HLA) phenotypes were determined.

RESULTS

Among males, a clear association, which was not explained by social class, was observed between chronic renal failure and high exposure to solvents for both MCN/FSH (OR = 7.7, 95% CI: 1.4-41.6) and IgA N (OR = 3.5, 95% CI: 1.0-11.8). The odds ratios increased with duration of exposure. No relationship was observed between such exposure and GN cases with normal renal function. No evidence was found that the HLA phenotype plays a role in the association between solvent exposure and the disease.

CONCLUSIONS

These results support the hypothesis of a causal relationship between high solvent exposure, which concerned 15% of the males in this study, and the development of GN with chronic renal failure.

Cell surface expression of major histocompatibility class I antigens is modulated by P-glycoprotein transporter

P-glycoprotein (Mdr1), a member of the ABC superfamily, is a pump able to transport several compounds across plasma membranes. It displays a high level of similarity with the MHC-linked transporters TAP1 and TAP2 which are involved in the delivery of immunogenic peptides across the endoplasmic reticulum. In the present study we analyze the P-glycoprotein's ability to interfere with the biosynthetic pathway of the MHC class I molecules. Our results show that P-glycoprotein is involved in the modulation of the MHC class I expression in multidrug-resistant tumor cell lines, COS1 cells transfected with mdr1 gene, and human T lymphocytes. Epitope screening evokes the possibility that P-glycoprotein induces a modulation of the different MHC class I forms expressed on the cell surface. We propose that P-glycoprotein is involved in the transport of antigenic protein fragments from the cytosol into the endoplasmic reticulum. The suggested mechanism could be physiologically relevant in tissues displaying a high Mdr1 activity, where this transporter could contribute to the regulation of locoregional immune responses.

Thalidomide does not perturb CD2, CD4, CD5, CD8, HLA-DR, or HLA-A, B, C molecules in vitro on the membranes of cells with immune potential

Thalidomide dramatically relieves the signs and symptoms of erythema nodosum leprosum (ENL). ENL is an acute inflammatory complication of lepromatous leprosy. The cause(s) of ENL as well as the mechanism of action of thalidomide in arresting ENL are unknowns. It has been suggested that ENL is the consequence of a transient activation of a cell-mediated-immune (CMI) response to Mycobacterium leprae. To initiate a CMI response, an interaction between adhesion and/or signal transducing molecules on T-cells and molecules on antigen presenting cells would occur. An alteration, induced by thalidomide, of one or more of the molecules on T-cells or antigen presenting cells that are essential to maintaining the reactive state of ENL, could explain Thalidomide's ability to attenuate ENL. Thalidomide did not modify: (a) adhesion and/or signal transducing molecules such as CD2, CD4, CD5 and CD8, or (b) molecules that facilitate antigen presentation such as HLA-DR, HLA-A, HLA-B, or HLA-C.

How interleukin-2 can affect human fibroblasts behaviour

The alpha and beta chains of the Interleukin 2 receptor (IL2R alpha and IL2R beta) were detected at the surface of cultured fibroblastic cells by flow cytometry, using monoclonal antibodies (mAbs) directed against the IL2R alpha and the IL2R beta. These cells bound FITC-IL2 and this binding was inhibited by an excess of cold ligand and by mAbs recognizing the IL2 binding sites of the alpha and beta chains. Internalisation studies show that the fibroblastic IL2R/IL2 complex is internalized at 37 degrees C. By Northern Blot analysis we detected the presence of specific transcripts for the IL2R alpha and IL2R beta genes. Finally, the addition of exogenous IL2 specifically modified the surface expression of different antigens involved in the process of immunosurveillance. Indeed, IL2, at concentrations affecting the high affinity IL2R, caused the down regulation of ICAM-1 protein. IL2 also decreased the surface expression of the class I and class II HLA. By contrast, the use of IL2 concentrations which saturate the intermediate affinity IL2R beta caused the up regulation of the surface expression of the ICAM-1 protein. ICAM-1 is the natural ligand for the LFA-1 integrin expressed at the surface of lymphoid cells. ICAM-1/LFA-1 interactions favour homotypic and heterotypic cell-cell adhesion. Since human fibroblasts express an LFA-1 like molecule, we propose that in these cells IL2 can modify homotypic and heterotypic interactions acting on the surface expression of ICAM-1 protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Upregulation and induction of surface antigens with special reference to MHC class II expression in microglia in postnatal rat brain following intravenous or intraperitoneal injections of lipopolysaccharide

The effects of bacterial lipopolysaccharide (LPS) on the expression of surface antigens including major histocompatibility complex (MHC) and complement type 3 (CR3) receptors on microglial cells in the corpus callosum in postnatal rat brain were investigated. When LPS was injected intravenously (i.v.) in 1-d-old rats, the immunostaining of callosal amoeboid microglial cells with OX-18 directed against MHC class I antigen was enhanced 24 h after the injection in comparison with the controls. The expression of MHC class II (Ia) antigen on the same cell type as shown by its immunoreactivity with OX-6 was also elicited especially after 2 intraperitoneal (i.p.) injections of LPS. Thus 7 d after a single i.p. injection of LPS into 1-d-old rats, only a few OX-6 positive cells showing a moderate staining reaction were observed in the corpus callosum. The immunoreactivity diminished 14 d after the injection. However, in rats receiving 2 successive i.p. injections of LPS at 1 and 4 d of age and killed 7 d after the 1st injection, a significant number of intensely stained OX-6 positive amoeboid microglial cells were observed in the corpus callosum. The expression of MHC class II antigens induced by 2 injections of LPS was sustained at least until d 14 when the callosal ramified microglial cells, known to be derived from gradual metamorphic transformation of amoeboid microglia, still exhibited intense immunoreactivity with OX-6. The effect of LPS on the expression of CR3 on amoeboid microglial cells was not obvious after a single injection, but the immunoreactivity with OX-42 was also augmented in rats given 2 i.p. administration of LPS into rats at 1 an 4 d of age. It is concluded from this study that the expression of MHC class I and class II antigens on amoeboid microglial cells in corpus callosum was upregulated and induced respectively after i.v. or i.p. injection of LPS into early postnatal rats. Although relatively fewer in number when compared with OX-18 and OX-42 positive cells, it is suggested that the OX-6 positive cells would have the potentiality to function in antigen presentation in the postnatal rat brain when challenged by the endotoxin.

Influence of suramin on the expression of Fc receptors and other markers on human monocytes and U937 cells, and on their phagocytic properties

Suramin, a polyanionic and polycyclic compound, was initially used for the treatment of trypanosomiasis and onchocerciasis. In the last decade, it has been used in therapy of cancer and acquired immune deficiency syndrome (AIDS). The influence of suramin on the expression of various markers by human mononuclear phagocytes is not known and was, therefore, presently investigated. Suramin inhibited the proliferation of U937 cells and mitogen-induced T-cell proliferation in a dose-dependent manner. The constitutive and cytokine-driven expression of Fc receptors for IgG (Fc gamma RI and Fc gamma RII), IgE (Fc epsilon RII) and IgA (Fc alpha R) on blood monocytes and U937 cells was suppressed by suramin. The basal level, as well as cytokine-induced major histocompatibility complex (MHC) class II antigens, was markedly diminished on suramin-treated monocytes. Furthermore, suramin dramatically reduced expression of CD14 and partially reduced complement receptor type 3 (CR3) and CR4 expression on monocytes. In contrast, suramin slightly induced MHC class I antigens on monocytes and CD71 on U937 cells. The capacity of monocytes to phagocytose IgG-sensitized ox erythrocytes, opsonized Escherichia coli, or fluorescein isothiocyanate (FITC)-conjugated latex beads was significantly inhibited. Northern blot analysis showed that the amount of Fc epsilon RII-specific mRNA was only partially reduced, suggesting that other mechanisms may be involved in the regulation of Fc epsilon RII expression. Our data demonstrate that suramin suppresses the expression of various cell-surface structures on human mononuclear phagocytes and impairs their phagocytic capacity.

Drug-induced lupus

Recent years have seen promising developments in both our appreciation of the spectrum of autoimmune phenomena associated with DIL as well as our understanding of the pathogenesis of this disease. From our present knowledge, it seems likely that the cause of DIL is multifactorial, and that the disease manifestations depend on both the drugs involved as well as predisposing host factors. The present availability of an animal model of DIL promises to further our understanding of the role of drugs and other environmental factors in this disorder. It is hoped that further studies will provide additional understanding of the pathogenesis of these lupus-like diseases and possibly bring us one step closer to providing more rational and effective treatments for patients with idiopathic lupus.

Regulatory effect of interferon-gamma and phorbol esters on the surface expression and biosynthesis of MHC class I antigens by human leukemia cells

We have used cell surface radioiodination, biosynthetic incorporation of [35S]methionine, and flow cytometry to analyze the effects of interferon gamma (IFN-gamma) and/or phorbol esters (PMA) on the turnover and expression of class I antigens of a human leukemia B cell line. Our results demonstrated that although both IFN-gamma and PMA enhance HLA expression, they act synergistically to increase by eightfold the amount of HLA polypeptides synthesized by the acute lymphoblastic leukemia cells and acted additively to augment the cell surface expression of HLA as quantified by flow cytometry. We observed a cyclic increase or decrease in the expression of class I antigens as a function of time in cell culture. IFN-gamma and/or PMA modulated this effect inducing more cells to express HLA maximally. These results suggest that there is a physiologic limit for the expression of major histocompatibility complex class I antigens.

Influence of chloroquine or acid treatment of human platelets on the antigenicity of HLA and the 'thrombocyte-specific' glycoproteins Ia/IIa, IIb, and IIb/IIIa

The influence of treatment of platelets with citrate buffer (pH 7.2), chloroquine, or citric acid at pH 3 on the expression of HLA class I antigens and 'thrombocyte-specific' glycoproteins was investigated by means of flow cytometry. After treatment with citric acid at pH 3 and chloroquine, the expression of HLA class I was significantly reduced, while the density of the molecules GPIa/IIa, GPIIb, and GPIIb/IIIa (GP = glycoprotein) carrying 'thrombocyte-specific' antigens was not or only weakly decreased on the surface of the platelets. The use of two monoclonal antibodies (HC-10 and HC-A2) against the native heavy chain of the HLA class I molecule revealed that 'antigen stripping' with chloroquine or citric acid does not affect the entire molecule: only the beta 2-microglobulin is cleaved, or only some epitopes on the heavy chain are altered by this procedure. The treatment with citric acid yielded better results with respect to the removal of HLA class I activity and the preservation of 'thrombocyte-specific' glycoproteins. The presence of the heavy chain of HLA class I molecules on the surface of platelets after treatment with citric acid and chloroquine confirms the hypothesis that platelets--like nucleated cells--bear HLA class I antigens inserted in the cell by a cytoplasmic and a transmembrane domain.

[The effect of 2-aminoethylisothiouronium bromide on HLA antigens]

Lymphocytes treated with a 6% and 4% AET solution after 60 or 120 minutes at 20 degrees or 37 degrees C display polyreactivity. Polyreactivity does not develop after short-term treatment (1-10 mins.). After treatment of lymphocytes with a 3% or 2% AET solution for a period of 20 or 30 mins. at 20 degrees or 37 degrees C the specific expresivity of HLA--A, B antigens rises; they are manifested, contrary to untreated lymphocytes, also by weak HLA sera. Addition of AET to the mixture of lymphocytes--HLA serum causes in the first stage of the microlymphocytotoxic test negativity of the test due to a block of the haemolytic activity of rabbit complement.

Effects of interferon gamma on the proliferation and modulation of cell-surface structures of human ovarian carcinoma cell lines

Platinum-containing regimens are very effective in the primary treatment of ovarian cancer. However, upon subsequent treatment most tumors develop multidrug resistance. The clinical application of biological response modifiers like interferon gamma (IFN gamma) in advanced ovarian cancer is therefore of increasing interest. Permanent ovarian cancer cell lines are suitable for investigating the mode of action and the potential clinical effectiveness of such response modifiers. IFN gamma is known to modulate many cellular functions. In this study it was compared for its antiproliferative and antigen-modulatory activity on the expression of tumor-associated (CA-125, HMFG, CEA) and major histocompatibility complex (MHC) class I and II antigens as well as of the epidermal growth factor (EGF) receptor on 20 newly established human ovarian carcinoma cell lines. IFN gamma in concentrations of 10, 50 and 100 U/ml was used to study its antigen-modulatory effect, and at additional 1 U/ml and 1000 U/ml to assess its antiproliferative effect on the cells. The cells were incubated with IFN for 4 days. Two cell lines showed strong antiproliferative activity even at minimal doses (up to 50 U/ml). Intermediate growth inhibition between 34% and 84% was observed in 15 cell lines with higher doses. Three lines were resistant to IFN gamma. Independent of the antiproliferative effect, IFN gamma enhanced the expression of MHC class I and MHC class II in nearly all cell lines. Upregulation was also observed for most of the tumor-associated antigens (TAA) and EGF receptor expression. A down-regulation was noticed but rarely. The fact that IFN gamma showed an antiproliferative activity on the majority of the cell lines is of clinical relevance. The in vitro modulation of cell-surface determinants by IFN gamma warrants special attention. The enhanced expression of TAA and MHC antigens can improve immunogenicity of the tumor cells and may explain the therapeutic effects observed under IFN therapy in ovarian cancer. By contrast, enhanced expression of the EGF receptor, often associated with poor patient survival rates, may be an undesirable side-effect of IFN therapy.

Effects of β-2 microglobulin anti-sense oligonucleotides on sensitivity of HER2/neu oncogene-expressing and nonexpressing target cells to lymphocyte-mediated lysis

The mechanism by which HER2/neu overexpressing tumor cells resist NK, LAK, and LDCC cytotoxic lymphocytes was investigated. Resistance was not explained by a delay in kinetics of lysis, concurrent resistance to TNF, or a diminished expression of the transferrin receptor. HLA-class I expression, however, was markedly elevated compared to HER2 nonexpressing targets suggesting a reason for resistance. To test the role of class I, we selectively decreased expression by incubation of targets with beta-2 microglobulin anti-sense oligonucleotides. Anti-sense-treated HER2+ targets, displaying levels of class I comparable to HER2- targets, were still markedly resistant to cytotoxic effectors. Down-regulation of class I expression in HER2- carcinoma cells also had no effect on sensitivity to cytotoxicity by anti-sense treatment of Raji and U937 targets resulted in enhanced sensitivity to NK and LAK effectors but not to T cells mediating LDCC. These data indicate resistance to cytotoxicity in HER2-expressing targets cannot be solely explained by heightened expression of class I. The data also support the concept that class I expression regulates sensitivity to NK and LAK cells (but not LDCC effectors) in selected targets.

[Changes in various differentiation-related markers after differentiation induction of a pluripotent human embryonal carcinoma (EC) cell line by hexamethylene bisacetamide]

A pluripotent human EC cell line (NEC14) could be induced to morphologically differentiate by treatment with 10(-2) M HMBA for 3 days in vitro. The changes in various differentiation-related markers (cell surface antigens, lectin binding sites, intermediate filaments, secreted products and extracellular matrix proteins) after induction of differentiation were examined in order to clarify the differentiation lineage. The results were as follows: 1) The most conspicuous changes in cell surface antigens after differentiation were the expression of major human histocompatibility antigens (HLA-A,B,C) and the changes in stage specific embryonic antigens (SSEA-1-/SSEA-3(+)----SSEA-1+/SSEA-3-). 2) Vimentin, mesenchymal intermediate filament, was only detected after the differentiation. 3) Tenascin, an extracellular matrix protein produced in mesenchymal cells, was produced after the differentiation. These results indicate that HMBA can induce NEC14 cells to differentiate into mesenchymal elements of embryonal mesoderm.

Ethanol influences class I and class II MHC antigen expression on human fetal islet-like cell clusters

Several autoimmune diseases have been linked to an aberrant expression of major histocompatibility complex (MHC) products Ethanol enhances Class I and Class II products on a variety of cell types, and there is evidence for an autoimmune etiology in numerous pathologies associated with alcoholism. We examined whether ethanol alters the expression of Class I and Class II MHC products on human fetal islet-like cell clusters. Incubation of islet-like clusters for 48 hr in ethanol at a starting concentration of 1.5% increased the percentage of single cells expressing Class I. The percentage of cells expressing Class II did not change, but their relative mean fluorescence increased significantly. These findings suggest that alcohol ingestion could alter MHC expression on pancreatic islet cells in vivo perhaps affecting the development of diabetes in genetically predisposed individuals. These findings also support the hypothesis that the rising incidence of type 1 diabetes seen in areas of the world where the per capita consumption of alcohol is also increasing may be a consequence of the immunological effects of alcohol intake.