A new MAGE gene with ubiquitous expression does not code for known MAGE antigens recognized by T cells

A number of genes of the MAGE family have been shown to code for antigens that are recognized on many human tumors by autologous CTLs. These antigens should be strictly tumor specific because the encoding MAGE genes are not expressed in normal adult cells, except for male germ-line cells, which lack HLA expression. Here, we report that a distant relative of the previously identified MAGE genes is expressed in many, if not all, normal tissues. This gene, which was named MAGE-D, is located in Xp11. Its exon-intron structure is completely different from that of the other MAGE genes. None of the 20 MAGE antigenic peptides presently known to be recognized by T lymphocytes is encoded by the new MAGE gene. It appears, therefore, that this new finding leaves intact the tumor specificity of the antigens encoded by the MAGE genes that are expressed only in tumor and germ-line cells.

HIV enteropathy: comparative morphometry of the jejunal mucosa of HIV infected patients resident in the United Kingdom and Uganda

AIMS

To compare jejunal mucosal morphometry in HIV infected patients resident in London and Uganda.

PATIENTS

Twenty HIV positive patients from London and 16 from Uganda were studied, and compared with HIV negative control subjects from both sites.

METHODS

Stools and biopsy specimens were examined for enteropathogens. Surface area to volume (S:V) ratio was estimated morphometrically, mean crypt length of jejunal biopsy specimens was measured, and HIV infected cells detected immunohistochemically were quantified.

RESULTS

Enteric pathogens were detected in none of the London patients, and in three Ugandan patients. S:V ratio was lower, and mean crypt length higher, in the specimens of London patients than in normal subjects, but there was no difference in S:V ratio or mean crypt length between Ugandan patients and controls. A negative correlation was present between S:V ratio and mean crypt length in all biopsy specimens analysed. HIV infected cells were detected only in lamina propria.

CONCLUSION

Infection of cells in the lamina propria of the jejunum with HIV stimulates crypt cell proliferation, and a fall in villous surface area. The mucosal response to HIV is masked by other pathogens in the African environment.

Detection of JC virus in two African cases of progressive multifocal leukoencephalopathy including identification of JCV type 3 in a Gambian AIDS patient

Progressive multifocal leukoencephalopathy (PML) is a fatal demyelinating central nervous system (CNS) infection, affecting mainly oligodendrocytes, but also occasional astrocytes. In the USA, Europe and Asia, PML is caused by the human polyomavirus JC virus (JCV) and in autopsy series occurs in about 4-7% of AIDS patients. In Africa, the prevalence of PML in AIDS patients is uncertain and the causative agent is unknown. This study reports immunocytochemical and PCR confirmation of PML in the CNS of an AIDS patient dying in Uganda, East Africa (case 1). In a Gambian patient infected with HIV-2 who died 3 months after onset of AIDS/PML in Germany (case 2), it was possible to confirm the identity of the virus by DNA sequencing of the PCR amplified JCV product. This African genotype of the virus (type 3) showed an unusual re-arrangement of the regulatory region, and could be distinguished at several sites from East African and African-American JCV strains described previously. This study has confirmed that PML is a complication of African AIDS as it is in Europe and the USA, and that JCV type 3 is pathogenic in African AIDS patients. Furthermore, the finding of an African genotype of JCV in a patient dying in Germany suggests that in this individual JCV represented a latent infection acquired in Africa.

LAGE-1, a new gene with tumor specificity

Representational difference analysis was used to identify genes that are expressed in a human melanoma cell line and not in normal skin. A cDNA clone that appeared to be specific for tumors was obtained and the corresponding gene was sequenced. This new gene was named LAGE-I. Using a LAGE-I probe to screen a cDNA library from the same melanoma cell line, we identified a closely related gene, which proved to be identical to NY-ESO-I, a gene recently reported to code for an antigen recognized by autologous antibodies in an esophageal squamous cell carcinoma. Gene LAGE-I maps to Xq28. It comprises 3 exons. Alternative splicing produces 2 major transcripts encoding polypeptides of 210 and 180 residues, respectively. Expression of LAGE-I was observed in 25-50% of tumor samples of melanomas, non-small-cell lung carcinomas, bladder, prostate and head and neck cancers. The only normal tissue that expressed the gene was testis. As for MAGE-AI, expression of LAGE-I is induced by deoxy-azacytidine in lymphoblastoid cells, suggesting that tumoral expression is due to demethylation. The expression of LAGE-I is strongly correlated with that of NY-ESO-I. It is also clearly correlated with the expression of MAGE genes.

[Rejection antigens of tumors and specific immunotherapy of cancer]

Human tumors carry antigens that are recognized by the patients' cytolytic T lymphocytes. An important group of antigens is coded by the MAGE family of genes. These antigens are expressed in a significant proportion of tumors of numerous histological types but not in normal tissues. Clinical trials are underway in an attempt to immunize patients suffering from metastatic melanomas using peptides coded by the MAGE genes. Regressions have been observed in 5 of the 17 immunized patients.

Identification of a new MAGE gene with tumor-specific expression by representational difference analysis

Human genes expressed exclusively in tumors and male germ line cells, such as those of the MAGE, BAGE, and GAGE families, encode antigens recognized by T lymphocytes, which are potentially useful for antitumor immunotherapy. To identify new genes of this type, we generated cDNA populations enriched in sequences expressed only in testis and melanoma, using the representational difference analysis approach. A testis cDNA library enriched by subtraction with cDNA from four other normal tissues was hybridized with radiolabeled melanoma cDNA enriched by subtraction with normal skin cDNA. A cDNA fragment sharing significant homology with MAGE genes was identified, and a cosmid containing this new gene, named MAGE-C1, was isolated. MAGE-C1 is composed of four exons and encodes a putative protein of 1142 amino acids. It is about 800 residues longer than the other MAGE proteins due to the insertion of a large number of short repetitive sequences in front of the MAGE-homologous sequence. The MAGE-C1 gene appears to be located on band Xq26, whereas the MAGE-A and MAGE-B genes are located on Xq28 and Xp21, respectively. Like other MAGE genes, MAGE-C1 is expressed in a significant proportion of tumors of various histological types, whereas it is silent in normal tissues except testis. It is probable, therefore, that like other MAGE genes, MAGE-C1 encodes antigens that may constitute useful targets for cancer immunotherapy because of their strict tumoral specificity.

[Liposome encapsulation of cystostatic drugs and starch microspheres improve tumor targeting in locoregional therapy. An animal experiment study of CC 531 liver tumor]

Systemic adjuvant chemotherapy achieves unsatisfactory results for inoperable liver tumors and metastases. Various clinical studies have shown that locoregional chemotherapy increased the survival rate by a few months. The aim of this study was to investigate tumor targeting of the most frequently used cytostatic 5-fluouracil by modifying systemic and locoregional therapy by liposome encapsulation. The tumor concentration of 5-FU encapsulated in SUV-PEG liposomes increases by a factor of 27 in systemic therapy and a factor of 90 in locoregional therapy. The tumor concentration of 5-FU increases by a factor of 8000, if the blood flow is additionally slowed by starch microspheres (Spherex) during locoregional therapy with liposome-encapsulated 5-FU.

Identification of human testis-specific transcripts and analysis of their expression in tumor cells

Tumor-specific antigens recognized by autologous T lymphocytes are encoded by genes, including those of the MAGE, BAGE, and GAGE gene families, that are expressed in a significant fraction of tumors of various types, but not in normal adult tissues, except for testis where they appear to be expressed in germ cells. Because male germ cells are known to express many genes that are not expressed in other normal adult tissues, we wished to determine whether most of these genes are occasionally activated in tumor cells. Representational difference analysis was used to obtain testis-specific transcripts. The expression of 15 testis-specific cDNA sequences was tested by RT-PCR in a series of tumor cell lines. Only one cDNA sequence showed a significant level of expression in some tumor cell lines. Remarkably, this cDNA clone proved to be a new gene of the MAGE family. These results suggest that MAGE, BAGE, and GAGE genes belong to a minor subset of testis-specific genes that is often activated in tumors of various types, whereas most testis-specific genes are either never or very rarely activated in tumors.

Comparison of bacillary indexes in slit-skin smears, skin and nerve biopsies; a study from Malawi

Data analyzed in this paper were collected within the framework of the Lepra Evaluation Project, an epidemiological study of leprosy in Karonga District, northern Malawi. For 212 patients information on the number of skin lesions, slit-skin smear and skin biopsy results were available. Among 61 patients with a single lesion none were slit-skin-smear positive and two had bacilli detected in skin biopsies. In contrast, among 119 patients with four or more lesions 34 (28.6%) versus 59 (49.6%) had bacilli detectable in slit-skin smears or skin biopsies, respectively. In a further 47 patients skin biopsy results could be compared with split-nerve biopsy results. In 20 of 47 patients the bacterial indexes (BIs) were identical in skin and nerve biopsies, while in 26 of 47 patients the BIs were higher in nerve than in skin biopsies. This difference, which is consistent with several other studies in the literature, provides an insight into the pathogenesis of leprosy.

A negative role for phosphoinositide 3-kinase in T-cell antigen receptor function

BACKGROUND

A delicate balance between positive and negative regulatory mechanisms during T-cell activation determines the specificity and magnitude of an immune response. Phosphoinositide 3-kinase (PI 3-kinase) is activated by a diverse set of receptors that determine T-cell function, including the T-cell antigen receptor (TCR), the costimulatory receptor CD28, and negative regulators of T-cell activation such as CTLA-4. PI 3-kinase is also regulated by the haematopoietic cytokines that determine T-cell differentiation and lymphocyte proliferation. PI 3-kinase can thus dynamically influence the outcome of the immune reactions at various stages. In this study, we investigated the importance of PI 3-kinase in TCR-directed T-cell activation using activated or inhibitory versions of PI 3-kinase.

RESULTS

Certain aspects of TCR responses such as the induction of transcriptional activity of AP1 and serum response factor were not affected by expression of the mutant forms of PI 3-kinase. We found, however, that PI 3-kinase profoundly influenced the transactivation capacity of 'nuclear factor of activated T cells' (NF-AT) elicited by the TCR: expression of an activated form of PI 3-kinase inhibited TCR-mediated NF-AT responses, whereas expression of a dominant negative mutant of PI 3-kinase potently enhanced TCR-controlled NF-AT induction. These effects of PI 3-kinase were not mediated by previously identified PI 3-kinase effectors, such as protein kinase B, a positive regulator of PI 3-kinase, or the GTPase Rac, and are therefore likely to involve a novel, as yet unknown, effector molecule.

CONCLUSIONS

Our results establish that PI 3-kinase can both positively and negatively regulate T-cell function, and uncover a previously unrecognized function for PI 3-kinase in T cells as a selective negative regulator of TCR-signalling events and therefore as a determinant of T-cell homeostasis.

Incidence of anti-mouse antibodies in thrombocytopenic patients with autoimmune disorders

Idiopathic thrombotycopenic purpura (ITP) is an autoimmune disorder in which circulating autoantibodies react with target antigens on the platelet membrane. In order to identify the autoimmune response in ITP, two MAIPA (Monoclonal Antibody (MAb) Immobilization of Platelet Antigen) assays (MAIPA I and MAIPA II) were performed on sera from thrombocytopenic patients. In the classic MAIPA assay (MAIPA I), control platelets were incubated simultaneously with human serum and a mouse MAb to a platelet glycoprotein. In MAIPA II, the control platelets were incubated first with the human serum and then, after washing, with the selected mouse MAb. A positive MAIPA I test but a negative MAIPA II has been shown to result from the presence of serum antibodies recognizing mouse MAb to platelet glycoproteins used in the assay. We compared the frequency of such 'anti-mouse' antibodies in patients with thrombocytopenia associated or not with other autoimmune states and in healthy donors with a normal platelet count. Statistically significant differences were found in the incidence of anti-mouse antibodies between patients and healthy donors. Furthermore, the identity of the targeted mouse MAbs varied in sera from the patients. The detected anti-mouse antibodies may include anti-idiotypic antibodies produced against cross-reactive idiotypes shared by human and mouse anti-platelet antibodies.

Erythema nodosum leprosum is associated with up-regulation of polyclonal IgG1 antibody synthesis

Erythema nodosum leprosum (ENL) is a serious complication of lepromatous (L) disease in leprosy. We have previously shown that of the four IgG subclasses, IgG1 and IgG3 Mycobacterium leprae-specific antibodies are significantly lower in leprosy patients during ENL reaction compared with untreated L patients. To see if this decrease results from a down-regulation of antibody synthesis during ENL, the frequency of antibody-secreting B cells (ABSC) in the blood compartment was determined by ELISPOT and related to serum immunoglobulin concentrations (microgram/ABSC). Control groups consisted of 16 patients with stable L disease and 32 healthy endemic controls (EC). Paired samples were analysed during acute ENLS (n = 13) and after the reaction had subsided to identify changes associated with ENL. Polyclonal (PC) IgG1 was elevated in L patients compared with EC (325 micrograms versus 180 micrograms). Interestingly, patients during acute ENL showed concentrations higher than L patients (419 micrograms), which decreased after the reaction had subsided (260 micrograms), indicating the transient nature of the antibody response. IgG2 antibodies showed the reverse trend and were lower during ENL and increased after the reaction had subsided. The mean concentrations for PC IgG3 and IgG4 antibodies were similar during ENL and after the reaction had subsided. Thus, decrease in M. leprae-specific IgG1 and IgG3 antibodies is not related to down-regulation of B cell responses. Identification of factors which regulate PC IgG1 antibody synthesis may provide additional insights into determinants of ENL reactions.

Prevalence and characteristics of brittle diabetes in Britain

We investigated the prevalence and characteristics of 'brittle diabetes', defined as insulin-dependent diabetes mellitus associated with glycaemic instability of any type, leading to life disruption with recurrent and/or prolonged hospitalizations. A questionnaire was sent to all physicians and paediatricians running diabetic clinics in the UK, from lists held at the British Diabetic Association. A total of 414 brittle patients were reported (72% questionnaire return). Most were young (mean age +/- SD was 26 +/- 15 years), though there was a small peak at ages 60-70 years. There was an excess of females (66%) and overall clinic prevalence was 1.2 per 1000 diabetic patients and 2.9 per 1000 insulin-treated diabetic patients. On average, there was 1.0 brittle patient per diabetic clinic. The most common form of brittleness was recurrent ketoacidosis (59%), with 17% having predominant hypoglycaemia, and 24% mixed instability. Female excess was highest and mean age lowest in the recurrent ketoacidosis group, whilst the reverse was true for those with recurrent hypoglycaemia. Causes of brittleness were offered by 58% of consultants, and most (93%) considered various psychosocial problems as likely underlying factors. We conclude that brittle diabetes is a small but significant problem, currently affecting about 1 per 1000 diabetic patients. Most, but by no means all, are young females--often with recurrent ketoacidosis. Older age groups are more likely to have recurrent hypoglycaemic or mixed types of brittleness. Perceived causes of brittleness are usually psychosocial.

Autoantibodies and anti-mouse antibodies in thrombocytopenic patients as assessed by different MAIPA assays

Two MAIPA (monoclonal antibody [MAb] immobilization of platelet antigen) assays were performed to determine (a) autoantibodies to platelet glycoproteins (GP) and (b) serum antibodies recognizing mouse MAbs used in the assay. In MAIPA I, control platelets were incubated simultaneously with human serum and a mouse MAb to a platelet glycoprotein (GP IIb-IIIa, Ib-IX, Ia-IIa, IV and p24). In MAIPA II, the control platelets were incubated first with the human serum and then, after washing, with the selected mouse MAb. A series of 25 patients with autoimmune thrombocytopenic purpura (ATP) associated or not with other autoimmune states were examined. Autoantibodies (both MAIPA I and MAIPA II positive) or anti-mouse Abs (MAIPA I positive and MAIPA II negative) were frequent in both groups of patients. Statistically significant differences existed in the incidence of anti-mouse Abs between patients (56.5%) and healthy donors (10%). This suggests that their production may be related to thrombocytopenias associated with autoimmune disease. We speculate that the presence of anti-mouse antibodies could reflect an abnormality in the immunological modulation of the idiotypic network.

The haemolytic uraemic syndrome in patients with AIDS

OBJECTIVE

Thrombotic microangiopathies have been increasingly recognised in HIV infection. The contribution of haemolytic uraemic syndrome (HUS) has not received as much emphasis as other members of the thrombotic microangiopathies. We describe the clinical features and prognosis of HUS in a group of patients with AIDS.

SETTING

St Bartholomew's and The Middlesex Hospitals, London.

PATIENTS

Five HIV seropositive individuals with clinical and histological features consistent with HUS.

INTERVENTIONS

Blood transfusion, fresh frozen plasma, haemodialysis, renal biopsy, autopsy.

CONCLUSIONS

HUS occurs in advanced HIV infection. Hypertension was a prominent clinical feature in HUS in this patient group. Measures to limit renovascular damage were unsuccessful and haemodialysis was usually needed to support renal function. The prognosis is poor, no patient achieved clinical remission and all died.

Acquired immunodeficiency syndrome and ocular calcification

We report the presence of peculiar nonbanded calcification of the cornea in three patients with acquired immunodeficiency syndrome, discovered on postmortem histological examination of the globes. In one patient, multiple calcium salt precipitates also affected other ocular and orbital structures. Calcium deposits were present in the corneal stroma but spared Bowman's layer, as is usually seen in primary and secondary corneal calcification. The calcified areas were positive to von Kossa, alizarin red, alcian blue, and colloidal iron stains. Electron probe analysis of the three cases showed the presence of calcium and phosphorus in a ratio characteristic for hydroxyapatite. No predisposing factors could be found. The possible role of associated alterations in the mucopolysaccharide content or composition in the calcified areas is unclear.

The protein interactions of the immunoglobulin receptor family tyrosine-based activation motifs present in the T cell receptor zeta subunits and the CD3 gamma, delta and epsilon chains

Immunoglobulin family tyrosine-based activation motifs (ITAM), which define the conserved signaling sequence EX2YX2L/IX7YX2L/I, couple the T cell antigen receptor (TCR) to cellular proteins including protein tyrosine kinases (PTK) and adapter molecules. The TCR is a multichain complex with four invariant chains CD3 gamma, delta and epsilon that each contain a single ITAM and the TCR zeta chain that contains three ITAM. The present study explores the protein interactions of the doubly phosphorylated CD3 gamma, delta, epsilon ITAM to determine whether they have common or unique biochemical properties. The data show that the doubly phosphorylated ITAM all bind the PTK ZAP-70, but the ITAM also variably bind the PTK p59fyn and the adapters Shc, Grb-2 and the p85 regulatory subunit of phosphoinositol 3' kinase. The CD3 and zeta ITAM display a hierarchy of ZAP-70 binding: zeta 1 = gamma = delta > zeta 3 > zeta 2 = epsilon. Shc, Grb-2 and p85 could bind the zeta ITAM and the CD3 gamma and delta ITAM, but not the CD3 epsilon ITAM. There were also subtle differences in the hierarchy of reactivity of these adapters for the CD3 gamma, delta and zeta ITAM that show that the zeta, CD3 gamma, delta and epsilon ITAM have different binding properties. The present study thus shows that the different ITAM of the TCR/CD3 complex can interact with different cytosolic effectors, indicating that differential ITAM phosphorylation during T cell activation could be a mechanism to generate signaling diversity by the TCR complex.