Outcome of Graves' disease after antithyroid drug treatment in Taiwan

The outcome of Graves' disease after treatment with antithyroid drugs (ATDs) varies widely among countries, and large-scale studies in Asia are rare. We investigated the associations of various clinical and laboratory features with the outcome of ATD therapy for Graves' disease in Taiwan. A total of 210 patients (177 women, 33 men; mean +/- SD age, 41.7 +/- 15.1 yr) treated with ATD in Taiwan were included. ATD therapy started with methimazole 30 mg daily or propylthiouracil 300 mg daily and was continued until a euthyroid state was achieved. Afterwards, 154 patients received a maintenance dose of ATD alone, while 56 patients received a combination of an ATD and thyroxine (L-T4). Patients were considered to be in remission if they remained in a euthyroid state for more than 2 years after drug withdrawal. The mean follow-up periods were 45.0 +/- 20.9 months for patients with remission and 30.4 +/- 19.8 months for those with relapse. Relapse occurred in 126 (60%) patients during the follow-up period, within 3 months after drug withdrawal in 47 (37%), and within 6 months in 60 (46%). The relapse rate was 100% among patients with two or more previous relapses. Patients with a second occurrence had a higher relapse rate than those with a first occurrence (84% vs 43%). Past history of recurrence, goiter size, thyroid-stimulating hormone level and thyrotropin-binding inhibition immunoglobulin activity at the end of ATD treatment were independently associated with relapse. Prolonged duration of treatment did not yield better results in patients with larger goiters or a history of recurrence, or both. Combination therapy with L-T4 yielded similar results to those achieved with ATD treatment alone. In conclusion, the relapse rate of Graves' disease after ATD treatment in Taiwanese patients was high, especially in those with a history of recurrence. The treatment duration and drug regimen did not affect the outcome.

In vitro culture growth of erythroid progenitors and serum erythropoietin assay in the differential diagnosis of polycythaemia

BACKGROUND

We assessed the in vitro culture growth of erythroid progenitors [burst forming unit-erythroid (BFU-E)] and serum erythropoietin (EPO) levels in different groups of polycythaemia to determine the discriminative power in differential diagnosis of polycythaemia.

METHODS

We used the methylcellulose culture technique to study the growth of endogenous erythroid colonies (EECs) and EPO-dependent BFU-E from bone marrow (BM) and/or peripheral blood (PB) cells from 40 patients with polycythaemia vera (PV), 13 with secondary polycythaemia (SP), 19 with pure erythrocytosis (PE), five with PE and PV evolution later (PE-PV), and 12 with relative polycythaemia (RP). The serum EPO levels were measured by radioimmunoassay before treatment in 47 patients, 23 SP patients, 19 PE patients, five PE-PV patients and 16 RP patients, as well as after treatment in 38 PV patients, five PE-PV patients and 12 PE patients.

RESULTS

The results of the erythroid progenitor culture assay showed that the numbers of EPO-dependent BFU-E in BM did not differ significantly among groups. The PB BFU-E were significantly higher in PV than in SP or PE, and no statistical difference were found among patients with SP, PE and RP. There was a correlation between BM BFU-E and PB BFU-E in the individual PV and PE patients. EECs were present in all BM and PB cultures of untreated and phlebotomy-treated PV and PE-PV patients, but were absent in 6 of 17 PV patients who had received cytotoxic therapy. EECs were not found in SP, PE and RP. PB could substitute for BM in the EEC or the BFU-E assay. Both pretreatment and post-treatment serum EPO levels of PV and PE-PV were similar, which were significantly lower than SP, PE or RP. The serum EPO levels in treated PV or PE-PV patients who had normal haematocrit values were not significantly different from those in untreated patients. In contrast, the phlebotomy-treated PE patients had significantly higher serum EPO values than untreated PE patients. In the differentiation between PV and PE, the sensitivity, specificity, positive predictive value and negative predictive value of post-treatment serum EPO levels at a cut-off level of < or = 9 UL-1 were 74%, 92% and 52% respectively. The discriminative power of post-phlebotomy serum EPO levels was even higher with a positive predictive value of 80% and negative predictive value of 92% for the prediction of PV evolution in patients with pure erythrocytosis of unknown origin.

CONCLUSION

The present study showed that apart from EEC assay, the post-phlebotomy serum EPO level was a sensitive and specific parameter in the differential diagnosis of polycythaemia, in particular for the identification of PV among patients with unclassifiable polycythaemia.

Effects of thrombopoietin on megakaryocyte colony formation from leukemic cells at diagnosis and from marrow cells after induction chemotherapy for acute leukemias

We have studied the effects of recombinant human thrombopoietin (TPO, mpl ligand) on the megakaryocyte colony formation from control human bone marrow cells, human leukemia cells at diagnosis, and human bone marrow cells after induction chemotherapy for acute leukemias. In the control human bone marrow cells from four adults and nine children who had localized malignancy and histologically normal-looking marrow. TPO alone effectively stimulated megakaryocyte colony formation, and interleukin-3 (IL-3) synergized this. In 17 patients (13 adults and four children) with acute myeloid leukemia (AML) at diagnosis, TPO stimulated leukemic colony formation in only one patient with FAB M7 subtype. In 11 children with acute lymphoblastic leukemia (ALL) at diagnosis, TPO did not enhance leukemic colony formation. After 17 courses of induction chemotherapy, nine for AML and eight for ALL, TPO stimulated megakaryocyte colony formation to a level of 51%, of that in the control human bone marrow cells. This may suggest that the administration of TPO to patients with M7 subtype warrants caution, whereas it is probably safe to give TPO at any time to patients with ALL. The administration of TPO to patients with acute leukemias after induction chemotherapy could stimulate megakaryocytopoiesis.

Blood and urine levels of tea catechins after ingestion of different amounts of green tea by human volunteers

The inhibitory activity of tea against tumorigenesis has been demonstrated in many animal models and has been suggested by some epidemiological studies. Such activity has generally been attributed to tea catechins. To understand the bioavailability of tea catechins in humans, we gave 18 individuals different amounts of green tea and measured the time-dependent plasma concentrations and urinary excretion of tea catechins. After taking 1.5, 3.0, and 4.5 g of decaffeinated green tea solids (dissolved in 500 ml of water), the maximum plasma concentration (Cmax) of (-)-epigallocatechin-3-gallate (EGCG) was 326 ng/ml, the Cmax of (-)-epigallocatechin (EGC) was 550 ng/ml, and the Cmax of (-)-epicatechin (EC) was 190 ng/ml. These Cmax values were observed at 1.4-2.4 h after ingestion of the tea preparation. When the dosage was increased from 1.5 to 3.0 g, the Cmax values increased 2.7-3.4-fold, but increasing the dose to 4.5 g did not increase the Cmax values significantly, which suggested a saturation phenomenon. The half-life of EGCG (5.0-5.5 h) seemed to be higher than the half-life of EGC or EC (2.5-3.4 h). EGC and EC, but not EGCG, were excreted in the urine. Over 90% of the total urinary EGC and EC was excreted within 8 h. When the tea dosage was increased, the amount of EGC and EC excretion seemed to increase, but a clear dose-response relationship was not observed. The present study provides basic pharmacokinetic parameters of green tea catechins in humans; these parameters may be used to estimate the levels of these compounds after drinking tea.

Severe granulocytopenia secondary to chlorpromazine despite concurrent lithium treatment: a case report

Severe chlorpromazine-induced granulocytopenia where the white-cell count decreases to below 1,000/mm3 rarely occurs and lithium is known to cause leucocytosis. The use of lithium in the prevention of granulocytopenia induced by drugs is still controversial. This report describes a patient with bipolar disorder suffering from severe granulocytopenia and severe respiratory infection after receiving chlorpromazine 50 to 150 mg per day along with long term lithium therapy. Bone-marrow aspiration and biopsy revealed inhibited maturation of myeloid series in the promyelocyte stage. The findings were consistent with a drug-induced effect. White-cell count return to normal after the discontinuation of chlorpromazine. It was proved in this case that combined lithium therapy had no effect in preventing agranulocytosis induced by chlorpromazine.

Granulopoiesis in newly diagnosed childhood solid tumors

Granulopoiesis at the diagnosis of solid tumors has not been previously reported. The purpose of this study is to detect the changes of granulopoiesis of patients with solid tumors in different clinical stages. Granulocyte-macrophage colony-forming unit (CFU-GM) assays and liquid suspension cultures of bone marrow and peripheral blood were studied in 90 children with newly diagnosed solid tumors, including 5 benign tumors and 85 malignant tumors. The malignant tumors were categorized into nonadvanced, advanced, or marrow-invaded ones. Bone marrow from children with immune thrombocytopenic purpura and peripheral blood from adult volunteers were used as controls. Granulocyte-macrophage colony formation from bone marrow in benign or nonadvanced malignant tumor was not significantly different from that of controls. However, granulocyte macrophage colony formation from bone marrow in advanced or marrow-invaded malignant tumor was significantly less than that of controls or nonadvanced malignant tumor. Furthermore, the bone marrow of patients with advanced malignant tumor occasionally had a defective proliferation pattern and the bone marrow of those with marrow-invaded malignant tumor often had a defective proliferation pattern. Peripheral blood in marrow-invaded malignant tumor had colony and cluster formations in very wide ranges. As a malignant tumor progresses into advanced stages, irrespective of marrow infiltration, bone marrow CFU-GM levels may decline and defective granulopoiesis may occur.

IgA myeloma associated with decreased anion gap and renal failure

The anion gap in myeloma patients had been well studied. IgG myeloma usually has decreased anion gap, whereas IgA myeloma always presents with normal anion gap. We report an unusual presentation of IgA myeloma with decreased anion gap and renal failure due to superimposing of acetazolamide-related bicarbonate loss.

Glucocorticoid remediable aldosteronism: a case report

Glucocorticoid remediable aldosteronism (GRA) is a hereditary cause of mineralocorticoid hypertension. The most common presentation is asymptomatic hypertension. Hypokalemia, hyperaldosteronism and suppressed plasma renin activity are other forms of primary hyperaldosteronism. However, the aldosterone secretion in these patients is regulated by adrenocortico-tropic hormone (ACTH) rather than the reninangiotension system. Here, we report a patient with a 12-year history of hypertension without response to any treatment until dexamethasone was administered. The diagnosis of GRA was confirmed by elevated plasma level of 18-oxocortisol, which is a unique steroid biochemical abnormality of this disease. In GRA, hybrid steroids (18-oxocortisol and 18-hydroxycortisol) are synthesized at the C-18 carbon of cortisol in a similar way as when corticosterone is converted to aldosterone. The gene duplication defect is on chromosome 8 codes for a chimerical 11 beta-hydroxylase/aldosterone synthase enzyme, causing ectopic expression of aldosterone synthase in zona fasiculata. Because this hypertension is remediable by exogenous glucocorticoid, this case was reported to raise attention about treatable aldosteronism.

Skin metastases from follicular thyroid carcinoma: a case report

Thyroid carcinomas metastasizing to the skin are rare. We report a case of skin metastases from a follicular thyroid carcinoma. A 73-year-old man developed multiple painless skin nodules about 6 years after thyroidectomy for the primary thyroid carcinoma. A biopsy disclosed a dermal tumor composed of small thyroid follicular structures with colloid material. The diagnosis was confirmed by immunohistochemistry using monoclonal antithyroglobulin antibodies performed on the skin biopsy specimens. The patient died 9 months later with multiple metastases after the development of skin lesions.

T cell epitope mapping of ragweed pollen allergen Ambrosia artemisiifolia (Amb a 5) and Ambrosia trifida (Amb t 5) and the role of free sulfhydryl groups in T cell recognition

Ambrosia artemisiifolia (Amb a 5; Ra5S) and Ambrosia trifida (Amb t 5; Ra5G) are homologous allergens purified from short and giant ragweed pollen, respectively. Allergic human sera and hyperimmunized animal antisera directed against Amb a 5 or Amb t 5 show a high degree of species specificity, with little or no cross-reactivity between these two allergens, suggesting that the major Ab binding epitopes of Amb a 5 and Amb t 5 are distinct. Overlapping synthetic peptides derived from the allergen sequences were used to investigate the specificity of T cell responses in four strains of mice, BALB/c (H-2d), CBA (H-2k), C57BL/6 (H-2b), and A/J (H-2a). All four strains of mice responded to purified Amb a 5 and Amb t 5. Cross-reactivity was found at the T cell level between Amb a 5 and Amb t 5 in T cells from BALB/c, A/J, and CBA mice, but not in T cells from C57BL/6 mice. A T cell epitope from Amb a 5, residues 27-36 (PWQVVCYESS), was mapped using T cell hybridomas from BALB/c mice. A T cell epitope in Amb t 5 was mapped in the same strain to residues 24-34 (KYCVCYDSKAI). Disulfide bonds in Amb a 5 and Amb t 5 were found to be involved in T cell reactivity. Conversion of disulfide bridges into free sulfhydryl (SH) forms was required for the response of T cell hybridomas to peptide t5 (residues 27-40) from Amb t 5. Reduction of peptide a4 (residues 21-37) from Amb a 5 was essential for inducing the cross-reactivity observed with Amb t 5-specific T cell hybridomas. It is concluded that free sulfhydryl groups play a major role in the T cell recognition of cross-reactivity T cell epitopes within these related allergens.

T cell epitope mapping of ragweed pollen allergen Ambrosia artemisiifolia (Amb a 5) and Ambrosia trifida (Amb t 5) and the role of free sulfhydryl groups in T cell recognition

Ambrosia artemisiifolia (Amb a 5; Ra5S) and Ambrosia trifida (Amb t 5; Ra5G) are homologous allergens purified from short and giant ragweed pollen, respectively. Allergic human sera and hyperimmunized animal antisera directed against Amb a 5 or Amb t 5 show a high degree of species specificity, with little or no cross-reactivity between these two allergens, suggesting that the major Ab binding epitopes of Amb a 5 and Amb t 5 are distinct. Overlapping synthetic peptides derived from the allergen sequences were used to investigate the specificity of T cell responses in four strains of mice, BALB/c (H-2d), CBA (H-2k), C57BL/6 (H-2b), and A/J (H-2a). All four strains of mice responded to purified Amb a 5 and Amb t 5. Cross-reactivity was found at the T cell level between Amb a 5 and Amb t 5 in T cells from BALB/c, A/J, and CBA mice, but not in T cells from C57BL/6 mice. A T cell epitope from Amb a 5, residues 27-36 (PWQVVCYESS), was mapped using T cell hybridomas from BALB/c mice. A T cell epitope in Amb t 5 was mapped in the same strain to residues 24-34 (KYCVCYDSKAI). Disulfide bonds in Amb a 5 and Amb t 5 were found to be involved in T cell reactivity. Conversion of disulfide bridges into free sulfhydryl (SH) forms was required for the response of T cell hybridomas to peptide t5 (residues 27-40) from Amb t 5. Reduction of peptide a4 (residues 21-37) from Amb a 5 was essential for inducing the cross-reactivity observed with Amb t 5-specific T cell hybridomas. It is concluded that free sulfhydryl groups play a major role in the T cell recognition of cross-reactivity T cell epitopes within these related allergens.

Primary plasma cell leukemia with extensive dense osteosclerosis: complete remission following combination chemotherapy

Diffuse osteosclerotic myeloma is very rare, and primary plasma cell leukemia with extensive osteosclerosis is even more rare. We describe a 71-year-old man who presented with severe anemia and dense widespread osteosclerosis similar to the X-ray finding of myelosclerosis. His peripheral blood showed 40% plasma cells. Bone marrow examination revealed heavy plasma cell infiltration with marked myelofibrosis and myelosclerosis. Protein electrophoresis and immunoelectrophoresis demonstrated an M-protein of IgG-lambda type. He was treated with cyclophosphamide, vincristine, and prednisolone for 10 months. A complete remission was obtained, with disappearance of M-protein and circulating plasma cells and normalization of complete blood counts, bone marrow picture, and biochemical parameters, as well as complete regression of myelofibrosis and osteosclerotic lesions. Unmaintained complete remission lasted for more than 1 year and he survived for more than 22 months. Our case indicated that one must include in the differential diagnosis of an osteosclerotic lesion the possibility of multiple myeloma, and that combination chemotherapy can induce a complete remission in this disease.

Cytokine responses during mycobacterial and schistosomal antigen-induced pulmonary granuloma formation. Production of Th1 and Th2 cytokines and relative contribution of tumor necrosis factor

Synchronized pulmonary granulomas (GRs) were induced in presensitized mice by intravenous embolization of polymer beads bound with purified protein derivative (PPD) of Mycobacteria tuberculosis or soluble antigens derived from Schistosoma mansoni eggs (SEA). Uncoated beads served as a foreign body control (CON). Antigen-coated beads elicited GRs with characteristic epithelioid macrophages and multinucleate giant cells by 4 days after embolization. Unlike PPD GR, SEA bead lesions contained eosinophils, whereas CON beads elicited only a limited mononuclear infiltrate. GRs and draining lymph nodes (LN) were assessed on days 2, 4, and 8 for Th1-(interleukin-2 [IL-2], interferon-gamma[IFN] and Th2-type (IL-4, IL-5, and IL-10) cytokines. CON GR produced only a small amount of IFN-gamma on day 2 and failed to induce a significant response in draining LN. In contrast, both PPD and SEA antigen-coated beads induced reactive lymphoid hyperplasia but differed greatly in local and regional cytokine profiles. PPD GR produced IFN-gamma on day 2 and the draining LN produced predominantly Th1 cytokines on days 2 and 4. In contrast, SEA beads GRs were dominated by Th2 cytokines. The corresponding LN produced IL-2 and IL-4 on day 2; IL-2, IL-4, IFN-gamma, and IL-10 on day 4; then IL-2, IFN-gamma, and IL-4 on day 8, probably reflecting maturational changes of T cells. Macrophages (MP) from bead GR also showed different patterns of IL-6 and tumor necrosis factor (TNF) production. Compared with CON GR, MPs from PPD GR were weak sources of IL-6, whereas those of SEA GR showed enhanced and accelerated production. In contrast, MP of PPD GR had augmented TNF-producing capacity, whereas those of SEA GR showed delayed TNF production. In vivo depletion of TNF, respectively, caused 40 and 10% decreases in PPD GR and SEA GR but had no effect on CON GR area, indicating that TNF contributed to a greater degree to the PPD response. These data show that depending on the inciting agent, GR can be mediated by different cytokines. Characterization of inflammatory lesions by cytokine profiles should allow design of more rational therapeutic interventions.

Inhibition of T-cell responses by feeding peptides containing major and cryptic epitopes: studies with the Der p I allergen

H-2b mice respond to the 222 residue allergen Der p I by producing T cells sensitized to the dominant epitopes encompassed in peptides 21-49, 78-100, 110-131 and 197-212. Immunization with the synthetic peptides 120-143 and 144-169, however, revealed cryptic epitopes which could sensitize T cells for responses to the respective peptides and, providing splenic adherent cells were added to lymph node cultures, to the whole allergen. It is shown that feeding recombinant fusion peptides can markedly inhibit the ability of the whole antigen to immunize mice, as measured by the in vitro interleukin-2 (IL-2) and granulocyte-macrophage colony-stimulating factor (GM-CSF)/IL-3 release on stimulation with protein or peptides, although inhibition measured by IL-2 release was more marked. The inhibition extended to epitopes other than those in the fusion peptides used for feeding. Thus feeding peptide 101-154 inhibited responses to 110-131 and 78-100. Fusion peptides 1-14 and 188-222 did not inhibit responses, although 188-222 did contain an epitope. Inhibition was also obtained when mice were fed a fusion containing the cryptic epitope 144-169. The ability of peptides containing the cryptic epitopes to inhibit responses has significant implications for peptide-based immunotherapy.

Cloning and sequencing of the Dermatophagoides pteronyssinus group III allergen, Der p III

House dust mites are widely recognized as major factors involved in the triggering of allergic diseases such as asthma. It is now apparent that the group III allergens of the Dermatophagoides mite species may play a significant role in a number of house dust mite allergic cases. Natural Der p III was isolated by gel filtration of salt precipitated Dermatophagoides pteronyssinus extract and as reported previously ran as a doublet of Mr 28 and 30 K on sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Natural Der fIII was isolated by affinity purification with the 5A12 monoclonal antibody. Amino acid sequence data was generated for both these proteins which was used to construct DNA probes to screen a Dermatophagoides pteronyssinus cDNA library by hybridization and resulted in the isolation of a recombinant Der p III cDNA clone, P3WS1. The 1059 bp cDNA fragment included a 786 bp open reading frame which encodes a pre-pro region of 29 amino acids and a mature protein of 232 amino acids with a calculated Mr 24,985. A search of the BLAST protein database has confirmed that the Der pIII P3WS1 clone is approximately 50% homologous with other trypsin proteins. We have confirmed with both our natural protein sequence and the P3WS1 amino acid sequence data that the group III allergens are trypsin-like proteins.

Differences in epitopes recognized by T cells during oral tolerance and priming

Feeding protein antigens to mice normally leads to the development of oral tolerance but under some circumstances, feeding can lead to immunity, for example, following pretreatment of mice with cyclophosphamide (CY). In both cases, however, it is possible to detect sensitized T cells in the spleen and mesenteric lymph nodes (MLN) by in vitro lymphokine release for granulocyte-macrophage-CSF (GM-CSF) and IFN-gamma. This study examines the recognition of the immunodominant T cell epitope on ovalbumin (OVA) following intragastric priming and tolerance. T cells from CY/OVA treated mice and cells from mice injected subcutaneously with OVA in CFA responded well to both OVA and the H2d restricted peptide epitope pOVA323-339 releasing GM-CSF. On the other hand MLN or spleen T cells from tolerized mice which responded to the protein in vitro did not recognize the immunodominant determinant. The cells responding from tolerized mice were restricted by the class II MHC so these results show there can be differential recognition of T cell epitopes between oral priming and tolerance.

Zinc and copper balances in healthy adult males during and after 17 wk of bed rest

The effects of long-term bed rest on zinc and copper balances were measured in seven healthy men. Volunteers aged 22-54 y (mean +/- SD, 34 +/- 12 y), 168-185 cm in height (173 +/- 5 cm), and 64-86 kg in weight (74 +/- 9 kg) remained on a metabolic ward for 29 wk. Subjects were ambulatory during weeks 1-5, remained in continuous bed rest for weeks 6-22, and were reambulated during weeks 23-29. Copper and zinc were measured in weekly urine and fecal composites. Dietary intakes provided (mean +/- SD) 19.2 +/- 1.2 mumol Cu (1.22 +/- 0.08 mg), 211 +/- 11 mumol Zn (13.81 +/- 0.72 mg), 25.2 +/- 1.2 mmol Ca (1011 +/- 46 mg), 1086 +/- 46 mmol N (15.21 +/- 0.65 g), and 48.1 +/- 1.4 mmol K (1489 +/- 44 mg)/d. Bed rest increased fecal zinc excretion and decreased zinc balance, whereas copper balance was unchanged. Reambulation decreased fecal zinc excretion and increased both zinc and copper balances. These results suggest that during long-term bed rest or space flight, individuals will lose total body zinc and will retain more zinc and copper when they reambulate.

Native and recombinant Fel dI as probes into the relationship of allergen structure to human IgE immunoreactivity

To delineate the relationship between the structural conformation and the stability of an allergen and its antigenicity, we have chosen the major allergen from cat dander, Fel dI. From protein sequence analysis data we have examined the structure of the naturally occurring Fel dI and we have found it to exist as an anti-parallel heterodimer. We have used ELISA, RAST, Western blot and histamine release techniques to compare the IgE reactivity of a set of cat allergic patient samples to purified, native Fel dI and the E. coli expressed chains 1 and 2. Results from these studies demonstrate a significant level of IgE reactivity to all forms when examined for direct binding. However, both blot and ELISA competition assays show a much higher reactivity to Fel dI in solution compared to the separate recombinant chains and this is supported by the histamine release data. Although native Fel dI chain 2 contains an N-linked carbohydrate moiety, this does not seem to play a role in the reactivity of IgE to chain 2. Denaturation of Fel dI with alkali conditions leads to a dramatic decrease in IgE reactivity, even though measurable changes to the backbone structure of the protein are minimal. One proposed explanation is that both chains possess a core region determined by their primary structures and that the major IgE epitopes are dependent upon them. The relative reactivity amongst these allergen forms varied with the method of analysis, implying that the conformational requirements for IgE antibody binding are best studied by the application of more than one experimental protocol. Results from these qualitative analyses afford insight into the allergenicity of this exceptionally stable cat pelt protein.

Presentation of peptides and proteins by intestinal epithelial cells

Murine intestinal epithelial cells (IEC) constitutively express major histocompatibility complex (MHC) class II molecules, which enable them to present foreign antigens to T cells in vitro. In this study we have compared the ability of freshly isolated IEC and spleen adherent cells to present both protein and peptide antigens to T cells in vitro. Consistently IEC were unable to present protein but could readily present immunogenic peptides in an MHC-dependent fashion to stimulate lymphokine release from T cells. Consistent with their inability to process protein antigens, IEC were also unable to present a synthetic peptide which requires intracellular processing, whereas spleen antigen-presenting cells (APC) could readily present the same peptide. These findings indicate that IEC may lack the necessary intracellular machinery to process exogenous antigens but they raise the possibility that IEC may play an important immunological role in vivo by presenting processed peptides to T cells.

Peripheral T-cell tolerance induced in naive and primed mice by subcutaneous injection of peptides from the major cat allergen Fel d I

T cells control the majority of antigen-specific immune responses. Therefore, influencing the activation of the T-cell response in order to modify immune responsiveness is an obvious therapeutic goal. We have used a mouse model of response to Fel d I, the major cat protein allergen in humans, to explore the ability of peptides derived from Fel d I to inhibit T-cell-dependent immune responses to the peptides themselves and to larger polypeptides. T cells from B6CBAF1 mice respond to the Fel d I peptide IPC-2 after challenge with IPC-2. However, subcutaneous tolerization with IPC-2 prevents this response as measured by production of interleukins 2 and 4 and interferon gamma. Fel d I immunization of B6D2F1 mice results in T-cell responses primarily to one peptide derived from Fel d I. Injecting this peptide in soluble form inhibits T-cell activation (as measured by interleukin 2 production) and antibody production in Fel d I-primed animals when they are subsequently challenged with peptide in adjuvant. Most of the cat-allergic human T-cell response to Fel d I is specific for two peptides on one of its two chains. Immunization of B6CBAF1 mice with recombinant Fel d I chain 1 results in T-cell responses to the same peptides. Subcutaneous administration of these two peptides, which contain some, but not all, of the T-cell epitopes from Fel d I chain I, decreases the T-cell response to the entire recombinant Fel d I chain 1. The ability to tolerize T-cell responses with subcutaneous injections suggests a practical approach to treating human diseases with peptides containing T-cell epitopes.

Purification and immunochemical characterization of recombinant and native ragweed allergen Amb a II

The complete sequence of a cDNA encoding Amb a II and its relationship to the Amb a I family of allergens has recently been described [Rogers et al. (1991) J. Immun. 147, 2547-2552; Griffith et al. (1991a), Int. Archs Allergy appl. Immun. 96, 296-304]. In this study, we present results generated with rabbit antipeptide antisera that recognize Amb a II or Amb a I, but not both. The specificity of two anti-Amb a II antipeptide sera, anti-RAE-50.K and anti-RAE-51.K, was verified on Western blots of recombinant Amb a II and Amb aI.1. These two sera, directed against separate regions of the Amb a II molecule, detected three individual 38-kDa Amb a II isoforms on 2D Western blots of aqueous ragweed pollen extract. These Amb a II isoforms have pI in the 5.5-5.85 range and can be easily distinguished from Amb a I isoforms with pI in the 4.5-5.2 range detected by an anti-Amb a I specific peptide antiserum. The Amb a II isoforms have also been individually purified from pollen, positively identified as Amb a II by amino acid sequencing, and visualized as separate bands on IEF gels. An analysis of Amb a II cDNA sequences generated by PCR led to the prediction of three Amb a II isoforms with pI of 5.74, 5.86 and 5.97 that are very similar to the pI deduced from 2D Western blot analysis. Recombinant Amb aI.1 and Amb a II have been expressed in E. coli, purified in their denatured form, and examined by ELISA for their capacity to bind pooled allergic human IgE. Purified native Amb a and Amb a II from pollen were shown to have very similar IgE-binding properties. In contrast, Amb a II had a markedly reduced IgE-binding capacity as compared to Amb a I.1. These data suggest that recombinant Amb a I.1 and Amb a II, isolated in a denatured form, differ significantly in their IgE-binding properties whereas the native molecules isolated from pollen do not.

Recombinant Fel d.I: Expression, purification, IgE binding and reaction with cat-allergic human T cells

This study describes the properties of the two recombinantly expressed polypeptide chains of Fel d I, the major allergen produced by the domestic cat (Felis domesticus). An inframe linker encoding polyhistidine has been added to the 5' ends of the Fel d I chains 1 and 2 cDNAs to facilitate purification using Ni2+ ion affinity chromatography. This method provides high yields in a single step of rchain 1 and rchain 2 of Fel d I with a > 90% level of purity. Polymerase chain reaction (PCR) methods were used to introduce a thrombin cleavage site (LVPR decreases GS) at the N-terminus of both chains. Thrombin cleavage of rchain 1 and rchain 2 followed by HPLC purification of the cleavage products allowed the isolation of each recombinant chain with only two additional residuals (GS) at the N-terminus of the native sequence. Amino acid sequencing analysis of the N-terminus and mass spectrometry of these polypeptides demonstrated that they are highly pure and full-length. Direct ELISA assays showed that IgE from cat-allergic patients binds to both rchain 1 and rchain 2 of Fel d I, demonstrating that both these chains contribute to the allergenicity of this heterodimeric protein. An examination of the reactivity of T cells derived from cat-allergic patients revealed that both polypeptide chains contribute to the T cell response to this allergen. Consequently, it is concluded that the immunological response to Fel d I is composed of a reaction at both the B and T cell level to each of the two chains that constitute the native allergen.

Characterization of T-cell responses to the house dust mite allergen Der p II in mice. Evidence for major and cryptic epitopes

Major histocompatibility complex (MHC) congenic strains can be defined as high and low responders to the major house dust mite allergen Der p II on the basis of the ability to sensitize T cells for in vitro lymphokine release. Mice of the H-2b haplotype were high responders, H-2k were intermediate and H-2d low responders. Like responses to other proteins, only a limited number of epitopes could be located by the response of T cells from mice immunized with allergen to a series of overlapping peptides. The epitopes for H-2b mice were 11-35, 78-104 and 105-129, 36-50 and 78-104 for H-2k mice and 36-60 for H-2d. Immunization with the peptides however revealed that spleen-adherent cells were required for lymph node cells to recall responses to the whole protein and in addition that mice could be sensitized by cryptic epitopes defined by peptides 22-50 and 1-20 for H-2b mice. Peptides containing these cryptic epitopes did not normally induce responses in mice primed with the allergen, but when they were used for immunizing they could prime mice for responses to the peptide and the whole allergen. The results both help to define a model for studying the presentation of allergens and have significant implications for peptide-based immunotherapy.

Comparison of antigen presentation by lymph node cells from protein and peptide-primed mice

Lymph node cells from mice primed with peptides from the allergens Der p I and Der p II (the group I and II allergens of Dermatophagoides pteronyssinus) were unable to recall responses to the protein antigen when cultured in vitro despite being able to mount large responses to the peptides. The T cells could however recall responses to the protein when spleen-adherent cells were added into culture. Treating the spleen accessory cells with the monoclonal antibody (mAb) 33D1 and complement largely abrogated the protein response of peptide-primed T cells which indicates that dendritic cells were mainly responsible for the antigen-presenting function. If mice were primed with two injections of peptide the lymph node cells obtained could respond to both protein and peptides in vitro without the need for exogenous accessory cells. Using either negative depletion with the J11D mAb or positive purification, it was found that the presentation of protein antigen to lymph node T cells primed with either protein or peptide was limited to antigen-specific B cells. Peptide antigens could however be presented by both B and non-B populations. In one case the peptide 105-129 from Der p II which contains a T-cell epitope could not be shown to induce T-cell responses in the lymph node unless presentation was mediated by spleen-adherent or B-specific cells. These results are important for peptide-based immunomodulation and in interpreting results obtained from lymph node cultures.