Neurofunctional imaging of ß-cell dynamics.

Here, we outline how islet cells use autocrine and paracrine 'circuits' of classical neurotransmitters and their corresponding receptors and transporters to communicate with vicinal ß-cells to regulate glucose-stimulated insulin secretion. Many of these same circuits operate in the central nervous system and can be visualized by molecular imaging. We discuss how these techniques might be applied to measuring the dynamics of ß-cell function in real time.

Prevalence of complementary and alternative medicine (CAM) use by the general population: a systematic review and update.

OBJECTIVES: To update previous systematic reviews of 12-month prevalence of complementary and alternative medicine (CAM) use by general populations; to explore trends in CAM use by national populations; to develop and apply a brief tool for assessing methodological quality of published CAM-use prevalence surveys. DESIGN: Nine databases were searched for published studies from 1998 onwards. Studies prior to 1998 were identified from two previous systematic reviews. A six-item literature-based tool was devised to assess robustness and interpretability of CAM-use estimates. RESULTS: Fifty-one reports from 49 surveys conducted in 15 countries met the inclusion criteria. We extracted 32 estimates of 12-month prevalence of use of any CAM (range 9.8-76%) and 33 estimates of 12-month prevalence of visits to CAM practitioners (range 1.8-48.7%). Quality of methodological reporting was variable; 30/51 survey reports (59%) met four or more of six quality criteria. Estimates of 12-month prevalence of any CAM use (excluding prayer) from surveys using consistent measurement methods showed remarkable stability in Australia (49%, 52%, 52%; 1993, 2000, 2004) and USA (36%, 38%; 2002, 2007). CONCLUSIONS: There was evidence of substantial CAM use in the 15 countries surveyed. Where national trends were discernable because of consistent measurement, there was no evidence to suggest a change in 12-month prevalence of CAM use since the previous systematic reviews were published in 2000. Periodic surveys are important to monitor population-level CAM use. Use of government-sponsored health surveys may enhance robustness of population-based prevalence estimates. Comparisons across countries could be improved by standardising approaches to data collection.

Differentiation-stage specific self-peptides bound by major histocompatibility complex class I molecules.

We have tested the hypothesis that phenotypic changes of development are accompanied by expression of differentiation-stage specific peptides bound to major histocompatibility complex (MHC) class I molecules. The U937 cell line, when cultured in the presence of phorbol myristate acetate (PMA), undergoes differentiation from monoblasts to macrophage-like cells. The high-performance liquid chromatography profile of peptides eluted from purified human histocompatibility leukocyte antigen class I molecules expressed by U937 treated with PMA differs from that obtained from control, untreated U937 cells. Chemical sequencing of eluted peptides identified a peptide derived from cytomegalovirus in both treated and untreated cells. PMA-treated, but not untreated cells, displayed an additional peptide derived from interleukin 1 beta. Hence, differentiation-induction of U937 is accompanied by the presentation of at least one differentiation-stage specific peptide. Our results indicate that, similar to viral infection, cellular development and transformation is accompanied by the de novo synthesis of proteins which are processed and presented on MHC class I molecules.

An effective CTL peptide vaccine for Ebola Zaire Based on Survivors' CD8+ targeting of a particular nucleocapsid protein epitope with potential implications for COVID-19 vaccine design.

The 2013-2016 West Africa EBOV epidemic was the biggest EBOV outbreak to date. An analysis of virus-specific CD8+ T-cell immunity in 30 survivors showed that 26 of those individuals had a CD8+ response to at least one EBOV protein. The dominant response (25/26 subjects) was specific to the EBOV nucleocapsid protein (NP). It has been suggested that epitopes on the EBOV NP could form an important part of an effective T-cell vaccine for Ebola Zaire. We show that a 9-amino-acid peptide NP44-52 (YQVNNLEEI) located in a conserved region of EBOV NP provides protection against morbidity and mortality after mouse adapted EBOV challenge. A single vaccination in a C57BL/6 mouse using an adjuvanted microsphere peptide vaccine formulation containing NP44-52 is enough to confer immunity in mice. Our work suggests that a peptide vaccine based on CD8+ T-cell immunity in EBOV survivors is conceptually sound and feasible. Nucleocapsid proteins within SARS-CoV-2 contain multiple Class I epitopes with predicted HLA restrictions consistent with broad population coverage. A similar approach to a CTL vaccine design may be possible for that virus.

Amplification of T cell blastogenic responses in healthy individuals and patients with acquired immunodeficiency syndrome.

Human immunodeficiency virus (HIV) infection is associated with a profound impairment of T cell function. Hence, enhancement of T cell reactivity to viral and bacterial antigens is important in the treatment of patients with AIDS. To develop tools for amplifying T cell reactivity, we have immunized mice with human helper T cell clones and selected monoclonal antibodies (MAbs) that enhance in vitro blastogenic responses. MAb NDA5, which recognizes the leukocyte common antigen CD45, amplifies human T cell responses to mitogens and soluble antigens including HIV-1 glycoprotein (gp)-120 and peptides derived from the HIV-1 gp-120 sequence. In the presence of MAb NDA5, peripheral blood mononuclear cells (PBMC) from healthy, HIV-1-seronegative individual displayed augmented blastogenic responses to HIV-1 gp-120 and to HIV-1 gp-120 synthetic peptides. In vitro memory responses to various vaccines and to alloantigens were also enhanced in cultures with MAb. Similarly, the response of PBMC from AIDS patients to pokeweed mitogen, HIV-1 gp-120, and tetanus toxoid was enhanced with MAb NDA5. The finding that the in vitro immune response of patients with AIDS can be amplified with MAb NDA5, suggests that the in vivo immune response of immunodeficient individuals can also be enhanced.

Immunopotency of a viral peptide assembled on the carbohydrate moieties of self immunoglobulins.

The T-cell receptor recognizes peptides bound to the major histocompatibility complex antigens. Synthetic peptides corresponding to microbial epitopes can efficiently stimulate the in vitro proliferation of T-cell hybridoma or in vivo primed T cells. However, the in vivo immune responses elicited by synthetic peptides are weak because of their short half-life and poor immunogenicity. We previously showed that a genetically engineered immunoglobulin (Ig-HA), in which the CDR3 region of VH gene was replaced with a viral peptide recognized by CD4+ T cells, was able to deliver this epitope in the correct frame to antigen-processing cells that efficiently presented the peptide to T cells. Recently, we developed an enzymatic method to assemble viral peptides on the sugar moieties of immunoglobulins without alteration of the biological functions of either molecule. The viral peptide carried by these conjugates was twenty times more efficient in activating a T-cell hybridoma than the free peptide as calculated on a molar basis. We show that such conjugates are able to prime in vivo the precursors of peptide-specific T cells and to induce proliferation of naive lymphocytes from transgenic mice expressing a peptide-specific T-cell receptor in both CD4 and CD8 T-cell subsets. Our results suggest that peptides enzymatically linked to the carbohydrate moieties of immunoglobulins, using galactose residues as peptide acceptor, can be used as a safe and efficient delivery system of protective epitopes for the prevention of infectious diseases. The enzymatic engineering of immunoglobulins may also allow the development of immunotherapeutic agents to deliver antagonist peptides to autoreactive T cells or to direct immunomodulatory agents such as interleukins or cytolytic drugs to tumor cells.

Distinct activities of interferon-gamma, lymphokine and cytokine differentiation-inducing factors acting on the human monoblastic leukemia cell line U937.

The human monoblast leukemia line U937 is growth inhibited and induced to express various characteristics of mature monocytes by lymphokines (LK) and other cytokines. Previous experiments have shown that interferon-gamma (IFN-gamma) is responsible for some but not all of the differentiation-inducing effects on U937. To determine the variety and specificity of activity, the following factors were studied: phytohemagglutinin-induced LK that contained IFN-gamma (100 units/ml); purified IFN-gamma; human colony-stimulating factor 1 (CSF-1); and conditioned medium(a) (CM) from the human bladder carcinoma cell line 5637 and the hepatoma cell line SK-HEP. LK preparations contained no colony-stimulating activity, whereas CM from 5637 and SK-HEP both contained granulocyte-macrophage CSF (3000 to 4000 units/ml) but no IFN activity. IFN-gamma is the major immunoglobulin G Fc receptor-inducing species within lymphokine, since anti-interferon-gamma antibody inhibited most of this activity. Other sources of Fc receptor-inducing activity were CM from SK-HEP and 5637 cell lines. Human CSF-1 when tested up to 800 units/ml was inactive for Fc receptor induction. LK induced the chemotactic peptide receptor, but this induction was due to factors other than IFN-gamma as anti-IFN-gamma antibody did not inhibit the induction, and purified IFN-gamma at a dose equivalent to that found in LK (100 units/ml) had no activity in the assay. SK-HEP and 5637 CM had strong chemotactic peptide receptor-inducing activity, but human CSF-1 was inactive up to 800 units/ml. Peroxide production after stimulation with phorbol myristic acid could be induced by LK, LK with anti-IFN-gamma antibody, 5637, and SK-HEP treatment. IFN-gamma (100 units/ml) and CSF-1 (800 units/ml) were ineffective. Peroxide production was induced by IFN-gamma at concentrations above 1000 units/ml. The inducibility of several enzymatic activities was determined as additional measures of maturation. N-Acetylglucuronidase was induced, for example, by LK, IFN-gamma, 5637 CM, and phorbol myristic acid. Alkaline phosphatase was induced by LK, IFN-gamma, dexamethasone, and phorbol myristic acid. 1,25-Dihydroxycholecalciferol was also examined and could induce most of the maturational markers examined. The results demonstrate that non-IFN cytokines from several sources have profound differentiation-inducing effects on monoblast leukemia cells in a pattern different from that of IFN-gamma.(ABSTRACT TRUNCATED AT 400 WORDS)

Distinct differentiation-inducing activities of gamma-interferon and cytokine factors acting on the human promyelocytic leukemia cell line HL-60.

The human promyelocytic leukemia cell line HL-60 and monoblastic leukemia cell line U937 undergo differentiation when induced by lymphokine and cytokine preparations. Growth inhibition, acquisition of immunoglobulin Fc receptors, increased expression of monocyte-related surface antigens, and an increase in lysosomal enzyme contents accompany maturation induced by gamma-interferon and other cytokine factors tested. Additionally, increased receptors for chemotactic peptide (fMLPR), increased hydrogen peroxide release in response to phorbol myristic acetate stimulation, and the release of prostaglandins (PGE2 and 6-keto-PGF1a) follow exposure to lymphokine and cell line sources of myeloid colony-stimulating activity (CSA). Gamma-Interferon (gamma-IFN) induced fMLPR in HL-60 (only at 1000 units/ml) but not in U937. Additionally, gamma-IFN did not induce prostaglandin release in either cell line. These myeloid colony-stimulating activity-associated differentiation-inducing factors were obtained from the human hepatoma++ cell line SK-Hep and bladder carcinoma cell line 5637, which were free of interferon activity. The 2-day phytohemagglutinin-induced lymphokine contained no detectable CSA and was a good source of differentiation activity. A simple, rapid assay for a new human CSA with pluripotent hematopoietic stimulating activity (pluripoietin) is described based on stimulation of [3H]glucosamine incorporation. Cell line conditioned media containing pluripoietin, purified pluripoietin, and gamma-IFN are active in this assay. These myeloid leukemia cell line differentiation factors are thus different from interferon and conventional CSA. These results suggest that endogenous human cytokines may have a role in the differentiation of leukemic as well as normal myeloid cells.

Tissue-specific self-peptides bound by major histocompatibility complex class I molecules of a human pancreatic beta-cell line.

The process of beta-cell destruction in IDDM is mediated, in part, by CD8+ T-cells. Structural characterization of HLA-I-bound self-peptides presented by the human beta-cell line HP-62 was performed to identify possible tissue-specific autoantigens in the context of CD8+ T-cell/HLA-I interactions. The sequences of the beta-cell line HLA-I-bound peptides were compared with sequence databases. Six of the obtained sequences showed homology to known precursor proteins, three of which--GLUT2 receptor, phosphatidylinositol-glycan-specific phospholipase D, and 5-hydroxytryptamine-1F receptor--have a limited, tissue-specific expression. These HLA-bound self-peptides may be part of a pool of autoantigens recognized by beta-cell reactive cytotoxic T-cells.

Self-peptides bound to HLA molecules.

The characterization of peptide bound to major histocompatibility complex (MHC) molecules has yielded insight to certain functional aspects of MHC molecules, the effects of MHC polymorphism, and the mechanism of antigen processing and presentation. The self-peptides bound to over 20 different human MHC molecules have been structurally analyzed, and they reveal information that complements our understanding of the three-dimensional structure of MHC molecules established by X-ray crystallography. Sequence analysis of individual self-peptides and the identification of their precursor proteins reveal the cellular geography of antigen processing and lays the foundation for advanced study of tolerance, autoimmunity, and anti-tumor immunity.

Wild-type p53 epitope naturally processed and presented by an HLA-B haplotype on human breast carcinoma cells.

To broaden the clinical applicability of peptide-based immunotherapy in breast cancer, there is a need to identify further tumor-associated peptide epitopes that are specific for HLA alleles, in addition to HLA-A2. The HLA-B44 haplotype is one of the most common HLA-B haplotypes, occurring in 10-20% of the population. We performed the structural characterization of HLA class I-bound self-peptides presented by a human breast cancer cell line with a HLA-A68, A32, B40, B44 haplotype, to identify potential tumor-specific antigens. Of 13 sequenced peptides, 1 peptide had the HLA-A68 peptide binding motif and 12 peptides had the HLA-B40, B44 peptide binding motif. One of the latter peptides, FEVRVCACPG, shared 100% homology to residues 270-279 of wild-type P53 protein. Our study, thus, provides direct evidence for the natural processing and presentation of p53 epitope 270-279 by HLA-B40, B44-bearing human breast tumor cells. Epitopes spanning this region of P53 may have potential use for immunotherapy in patients expressing HLA-A2 and -B44 supertypes.

Dynamic regulation of follicle-stimulating hormone-beta messenger ribonucleic acid levels by activin and gonadotropin-releasing hormone in perifused rat pituitary cells.

Maintenance of FSH biosynthesis requires ongoing exposure to pulsatile GnRH. Recent data demonstrate that activin also stimulates FSH biosynthesis. We used a perifused pituitary system to examine regulation of FSH beta mRNA levels by pulsatile GnRH and activin. Hourly pulses of 10 nM GnRH increased FSH beta mRNA levels by 3-fold. In the same experiment, continuous infusion of 50 ng/ml activin elicited a 50-fold increase in FSH beta mRNA. This magnitude of response to activin in perifusion was unexpected, as only a 2.7-fold increase in FSH beta mRNA was observed when activin was administered to pituitary cells that were cultured in dishes. Since perifusion columns, unlike culture dishes, are exposed to a continuous supply of fresh medium, we examined the possibility that endogenous factors produced by pituitary cells cultured in dishes were stimulating the cells in a paracrine fashion, thereby precluding the full response to exogenously added activin. The kinetics of FSH beta mRNA expression were examined immediately after pituitary dispersion and at different times after culturing the cells in plates. FSH beta mRNA levels fell rapidly after dispersion to 8% of initial levels and remained low over 8 h. Thereafter, FSH beta mRNA levels increased slowly and exceeded initial levels by the second day of culture. In a parallel set of experiments, when medium conditioned by exposure to plated cells was applied to the perifusion system, FSH beta mRNA levels were selectively stimulated (6-fold). These data suggest the removal during dispersion and subsequent accumulation in culture of pituitary-derived factors that are important for the maintenance of FSH beta mRNA levels. We conclude that activin plays a greater role in the regulation of FSH beta mRNA levels than was suggested by previous experiments employing static culture systems in which autocrine or paracrine stimulation may have obscured the effects of exogenously added activin.

G protein and thyrotropin receptor mutations in thyroid neoplasia.

The cAMP pathway plays a central role in thyroid follicular cell growth and function. Mutations of the TSH receptor (TSHR) or G proteins (gsp) that activate adenylyl cyclase have been identified in autonomously functioning thyroid nodules. Gsp mutations have been identified also in other forms of thyroid neoplasia, but their reported prevalence has been extremely variable. We have studied the prevalence of gsp mutations and activating mutations of Gi2 alpha (gip) in a series of 66 benign and 34 malignant thyroid tumors. Thirty-six tumors were from Boston and 64 from the UK. In addition, we examined the 64 UK tumors for mutations of the TSHR gene. DNA extracted from fresh-frozen or paraffin-embedded tissue was amplified by PCR and examined for mutations using oligonucleotide-specific hybridization and single-strand conformation polymorphism analysis. No G protein gene mutations were identified in the Boston tumors. One gsp mutation, R201C, in a Hürthle cell adenoma and 1 gip mutation, R179C, in a follicular adenoma were demonstrated in tumors from the UK. Oligonucleotide-specific hybridization and single-strand conformation polymorphism analysis of the UK tumors did not demonstrate any mutations of the TSHR gene. Eleven normal thyroid tissue samples were wild-type for Gs alpha, Gi2 alpha, and the TSHR gene.

G protein gene mutations in patients with multiple endocrinopathies.

Point mutations of G protein genes that result in the constitutive activation of G proteins have been described. Such mutations have been shown to occur in a number of endocrine diseases. We have examined tissues from patients having more than one organ affected by an endocrine disorder and patients having separate distinct endocrine diseases for G protein gene mutations. G protein genes encoding for Gs alpha and Gi2 alpha were examined for activating mutations at codons 201 and 227 (Gs alpha) and codons 179 and 205 (Gi2 alpha) using site-directed oligonucleotide hybridization and direct sequencing of tissue DNA amplified by polymerase chain reaction. Tissues from six patients were examined. The only mutation that was identified was at codon 201 of Gs alpha (gsp), which encoded a change from arginine to cysteine. Patient 1 had the mutation in a corticotroph adenoma, a chemodectoma, and a nodular hyperplastic adrenal gland. patient 2 had the mutation in an extraadrenal pheochromocytoma, but an adrenal gland with medullary hyperplasia was wild-type. Patient 3 had an aggressive corticotroph adenoma and developed Nelson's syndrome after bilateral adrenalectomy. The corticotroph adenoma was wild-type, but both hyperplastic adrenal glands had the mutation. Patient 4 had the mutation in a parathyroid adenoma and in two hyperplastic parathyroid glands. Patient 5 had the mutation in both a primary and a metastatic pheochromocytoma. Patient 6 had the mutation in a parathyroid adenoma and also in histologically normal thyroid and parathyroid tissue. Leukocyte DNA was examined from five patients and was found to be wild-type in all cases. We conclude that G protein gene mutations occur in a wider range of endocrine conditions than has been recognized hereto. In addition, the presence of gsp mutations in different endocrine disorders in the same patient is suggestive of a common underlying etiology.

Glycoprotein hormone alpha-subunit production in somatotroph adenomas with and without Gs alpha mutations.

Activating mutations of the Gs alpha subunit have been identified in a subset of somatotroph adenomas. The mutant form of the Gs alpha subunit causes persistent activation of adenylyl cyclase and consequently results in high intracellular levels of cAMP. Because cAMP is known to stimulate the synthesis of the glycoprotein hormone (GPH) alpha-subunit as well as GH, we examined somatotroph tumors with and without Gs alpha mutations for GPH alpha-subunit production. GPH alpha-subunit production was assessed in vivo by measuring serum hormone levels and in vitro by analyzing hormone secretion by cultured pituitary tumor cells. DNA was extracted from the pituitary tumors of 26 acromegalic patients. The Gs alpha gene was amplified by the polymerase chain reaction and screened for mutations at codons 201 and 227 using oligonucleotide specific hybridization. Nine of the 26 tumors (35%) had point mutations at Arg 201. Seven of these tumors contained a CGT to TGT mutation (Arg to Cys) and 2 contained a CGT to CAT mutation (Arg to His). No mutations were detected at codon 227. There were no significant differences in age, sex distribution, tumor size, or serum levels of GH or insulin-like growth factor-1 between the groups of patients with or was Gs alpha mutations. The mean serum level of the free GPH alpha-subunit was 1.9-fold higher in the group with Gs alpha mutations (0.48 +/- 0.37 micrograms/L) than in patients without mutations (0.25 +/- 0.17) (P less than 0.05). In pituitary tumor cell culture, 75% of somatotroph tumors with Gs alpha mutations secreted free GPH alpha-subunit into the media compared with 45% of tumors without Gs alpha mutations. The amount of GPH alpha-subunit secretion was 12-fold greater in the group of tumors containing the Gs alpha mutation (P less than 0.05). Immunocytochemical detection of the free GPH alpha-subunit was similar in the two groups of patients with 75% positive for the GPH alpha-subunit in tumors with Gs alpha mutations and 67% positive in tumors without mutations (P = 0.69). We conclude that GPH alpha-subunit production occurs in somatotroph tumors with and without Gs alpha mutations. The increased levels of GPH alpha-subunit secretion in vivo and in vitro suggest that the Gs alpha mutation may increase the amount of preexisting GPH alpha-subunit biosynthesis in the tumors, perhaps via activation of the cAMP pathway.

Metastatic prolactinoma: effect of octreotide, cabergoline, carboplatin and etoposide; immunocytochemical analysis of proto-oncogene expression.

A 49-yr-old woman presented with an extensive prolactinoma (serum PRL > 10,000 mU/L, normal range < 450 mU/L). Over a 5-yr period following transsphenoidal surgery and pituitary irradiation, she became increasingly resistant to high doses of bromocriptine and underwent transfrontal surgery followed by stereotactic radiotherapy. In spite of these treatments, serum prolactin estimations rose progressively to > 100,000 mU/L. Magnetic resonance imaging scanning demonstrated a massive cystic tumor invading the temporal lobes, extending into the cervical and thoracic spine, with metastases to cervical lymph nodes. High-dose cabergoline administration resulted in a 30% decrease in serum PRL. Octreotide was administered as a continuous sc infusion with a profound analgesic effect on facial pain but with no effect on tumor progression. She was treated with a course of chemotherapy consisting of carboplatin and etoposide without any noticeable effect. The patient died 6 months following chemotherapy. Immunocytochemical analysis demonstrated positive nuclear staining for WAF-1, Rb protein, c-myc, and p53 both in the original and metastatic tumors. The metastases but not the primary tumor stained for c-jun. Metastatic prolactinoma remains a therapeutic challenge. It is associated with a variable proto-oncogene expression, which may be coincidental or causal. Cabergoline had no advantage over bromocriptine. Octreotide relieved facial pain but did not alter tumor progression. An effective therapy for metastatic prolactinoma remains to be identified.

Primary medical therapy for acromegaly: an open, prospective, multicenter study of the effects of subcutaneous and intramuscular slow-release octreotide on growth hormone, insulin-like growth factor-I, and tumor size.

Conventional surgery and radiotherapy for acromegaly have limitations. There are few data on the use of the somatostatin analog octreotide (Oct) as primary medical therapy. An open prospective study of 27 patients with newly diagnosed acromegaly was conducted in nine endocrine centers in the United Kingdom. Twenty patients had macroadenomas, and 7 had microadenomas. For the first 24 wk (phase 1), patients received sc Oct in an initial dose of 100 microg, 3 times daily, increased to 200 micro g three times daily after 4 wk in the 13 patients whose mean serum GH remained greater than 5 mU/liter (2 microg/liter). Five-point GH profiles were performed at 0, 4, 12, and 24 wk, and high resolution pituitary imaging using a standard protocol was performed at 0, 12, and 24 wk (magnetic resonance imaging in 25 patients and computed tomography in 2). Tumor dimensions and volumes were calculated by a central, reporting neuroradiologist, and the results were audited by a second, independent neuroradiologist. After 24 wk, 15 patients proceeded to phase 2 of the study with a direct switch to monthly injections of the depot formulation of Oct, Sandostatin long-acting release (Oct-LAR). Further GH profiles were performed at 36 and 48 wk, and pituitary imaging was performed at 48 wk. The median pretreatment serum GH concentration was 30.7 mU/liter (range, 6.7-141.4). During sc Oct, serum GH fell to less than 5 mU/liter in 9 patients (38%), and IGF-I fell to normal in 8 patients (33%). All 27 tumors shrank during sc Oct; for microadenomas the median tumor volume reduction was 49% (range, 12-73), and for macroadenomas it was 43% (range, 6-92). After 24 wk of Oct-LAR (end of phase 2), the GH level was less than 5 mU/liter in 11 of 14 patients (79%), and IGF-I was normal in 8 of 15 patients (53%). In the 15 patients given Oct-LAR (10 macroadenomas), wk 48 scans showed a further overall median tumor volume reduction of 24%. At the end of the study 79% of patients had mean serum GH levels below 5 mU/liter, 53% had normal IGF-I levels, and 73% showed greater than 30% tumor shrinkage. Twenty-nine percent of patients achieved all 3 targets, but no patient with pretreatment GH levels above 50 mU/liter did so at any stage of the study. Primary medical therapy with Oct offers the prospect of normalization of GH/IGF-I levels together with substantial tumor shrinkage in a significant subset of acromegalic patients. This is most likely to occur in patients with pretreatment GH levels less than 50 mU/liter (20 microg/liter).

Major histocompatibility complex-restricted recognition of autologous chronic lymphocytic leukemia by tumor-specific T cells.

From the peripheral blood of a patient with chronic lymphocytic leukemia (CLL) we generated a T-cell line and clones which recognized autologous CLL. The line comprised T-cell clones which responded to the CLL as well as to autologous Epstein-Barr virus (EBV)-transformed B cells in an HLA-DR-restricted fashion. In addition, the line comprised clones which were CLL-specific and showed no reactivity against EBV-transformed B cells and against autologous peripheral blood mononuclear cells obtained during remission. The proliferative response of the CLL-specific T-cell clone was inhibited by monoclonal antibodies to HLA-DR11, the major histocompatibility complex (MHC)-restrictive element. These results indicate that the MHC class-II molecule of CLL binds a tumor-specific peptide which is recognized by autologous T cells in an MHC class-II-restricted fashion. Such a peptide may serve as a target for immunotherapy.

Monitoring of soluble HLA alloantigens and anti-HLA antibodies identifies heart allograft recipients at risk of transplant-associated coronary artery disease.

The development of accelerated transplant-related coronary artery disease (T-CAD) is the major obstacle to long-term survival of cardiac allografts. We have investigated the role of various demographic and immunologic parameters as prognostic indicators of T-CAD in a population of 274 heart allograft recipients. Our data demonstrate that patients who experience more than 1 episode of acute rejection per year and/or develop antidonor HLA antibodies are at increased risk of developing T-CAD. Using HLA-A2 as a marker for the release of soluble HLA antigens from the donor, we established that recipients displaying circulating donor alloantigens for more than 26 weeks following transplantation are at increased risk of developing T-CAD (P=0.008). This association suggests that the release of alloantigens from the allograft is indicative of chronic injury and/or that it stimulates chronic rejection via the indirect allorecognition pathway. Our findings indicate that patients at risk of developing T-CAD can be identified by monitoring the release of donor alloantigens and production of antidonor HLA antibodies following transplantation.

MHC class I antigen processing pathways.

The multistep process that culminates in major histocompatibility complex (MHC) class I presentation of foreign of self-peptides begins in the last phases of protein catabolism. Although the individual roles of many key molecules-such as proteasomes, the transporter associated with antigen processing, and various endoplasmic reticulum chaperones-have recently been elucidated, there still remain many questions regarding processing of proteins into MHC class I bound peptides. This review summarizes the recent developments in antigen processing for MHC class I molecules, with a focus on how proteins are believed to be sampled and selected for degradation.