Partial activation of human T cells by peptide analogs on live APC: induction of clonal anergy associated with protein tyrosine dephosphorylation

T-cell clonal anergy induced by peptide analogs in the presence of live APC in murine systems was reported to be associated with incomplete tyrosine phosphorylation of the CD3 zeta chain followed by a lack of subsequent ZAP-70 recruitment. Furthermore, protein tyrosine phosphatase SHP-1 was associated with ZAP-70 upon T-cell activation, leading to a dominant negative signaling. In this study, we used nonself BCGa-specific human ThO clones and investigated the antagonistic/partial agonistic activities of one-residue-substituted analog peptides. The results showed that (a) certain one-residue-substituted analogs can partially activate T cells to produce lymphokines, without proliferation; (b) a peptide with a conservative one-residue substitution can induce T-cell anergy in the presence of live APC, but T cells are capable of responding to exogenously added IL-2; and (c) the induction of anergy is accompanied by marked dephosphorylation of a 110-kDa protein, without either upregulation of CD25 or any changes in CD3 zeta phosphorylation patterns, suggesting that TCR-mediated dominant negative signaling through phosphatase(s) in another mechanism that may lead to the induction of T-cell clonal anergy by altered TCR ligands.

Encapsulated fat necrosis in a patient with Ehlers-Danlos syndrome

Mobile encapsulated lipoma, first described by Sahl in 1978 (1), is characterized by its great mobility within subcutaneous adipose tissue and presentation with or without tenderness when the nodules are manipulated. This lipoma's histopathology is very characteristic; i.e., it consists of mature viable or degenerative lipocytes encapsulated by fibrous tissue. We report a case of this so-called mobile encapsulated lipoma involving a patient with Ehlers-Danlos syndrome. This case is the first report of mobile encapsulated lipoma in a patient with a disease of this type. We discuss its pathogenesis and the nomenclature for these lesions.

Evaluation of peptide-HLA binding by an enzyme-linked assay and its application to the detailed peptide motifs for HLA-DR9 (DRB1*0901)

In our recent studies, we identified HLA-DRB1*0901-binding peptides by affinity-based selection of a phage random peptide library and showed that two major anchors (WxxS, where x is any amino acid) play an essential role in binding to DR9, determined using a radioactive peptide in combination with column chromatography. In the current study, we established an ELISA-based peptide-HLA binding assay system, with a new index (relative binding affinity: r.b.a.) for quantitation of peptide-HLA binding, using standard curves of competitive inhibition, an approach which enabled handling of a larger number of samples simultaneously. Quantitation of binding between HLA-DR9 molecules and 39 synthetic peptides showed that: (a) this system yields results which correlate with those obtained using the previous assay system (Spearman's rank correlation coefficient; the p value of the putative first anchor < 0.001, and the putative second anchor < 0.001); and (b) substituting the putative first (the most N-terminal) anchor Trp to Y, M, F, I, L, V, or C, and the putative second anchor Ser to T, G, A, V, F, or H, allow high-affinity binding to DR9.

A case of disseminated superficial actinic porokeratosis subsequent to renal transplantation

Disseminated superficial actinic porokeratosis is characterized by the development of numerous annular keratotic lesions on sun-exposed areas, accompanied by pathological evidence of cornoid lamellae. We examined a case of disseminated superficial actinic porokeratosis in a 40-year-old male who had undergone renal transplantation and was being treated with immunosuppressants. Five years after surgery, he began to develop numerous eruptions. Some of these eruptions enlarged and developed over a second period of five years until he finally required hospitalization.

Differential binding of peptides substituted at putative C-terminal anchor residue to HLA-DQ8 and DQ9 differing only at beta 57

HLA-DQ8 (DQA1*0302-DQB1*0302: DQ beta 57 Ala) and (DQA1*0302-DQB1*0303: DQ beta 57 Asp) differ only at beta 57, at which polymorphism reportedly confers distinct susceptibility to insulin-dependent diabetes mellitus (IDDM). To identify the differential peptide binding affected by beta 57, we determined DQ9-binding peptides by affinity-based selection of a phage random peptide library using the biotinylated DQ9 complex. Nonconservative single-residue substitution of high-affinity DQ8- and DQ9-binding peptide (1KLPDYVLWSSSTVVGLGAAGA21) at the underlined residues significantly decreased the peptide binding to DQ8 and DQ9. Affinities of the wild-type 21-mer K4DYVLWSSSTV13 and K4AYAAWAAATA13 to DQ8 and DQ9 were practically the same. The K4DYVLWSSSTV13-based analogue peptides with substitutions at 12T showed that residues R, K, H, E, D, Q, N, T, S, V, L, I, F, M, W, and Y permitted binding to DQ8, whereas only R, T, V, L, I, F, M, W, and Y did so to DQ9. Thus, significant differences exist between DQ9 and DQ8, in that the majority of polar residues, regardless of their static charges at the residue 12, permitted binding to IDDM-susceptible DQ8, which is not the case for DQ9. The affinities of K4DYVLWSSSXV13 AND K4AYAAWAAAAX13 (where X is T, A, K, D, or I) were almost equal to DQ8 and DQ9, suggesting the DQ8- and DQ9-binding peptide motifs could accept both the 8-mer and 9-mer frames depending on intervening sequences between N- and C-terminal anchor residues. The biochemical basis of peptide-HLA interactions determined by DQ beta 57 is discussed.

Augmentation of immune response by an analog of the antigenic peptide in a human T-cell clone recognizing mutated Ras-derived peptides

T-cells that recognize mutated p21 Ras are relevant to immune surveillance systems against cancer. We report here evidence that immune responses of a T-cell clone recognizing mutated p21 Ras can be augmented by an analog peptide. Using spleen cells from a gastric cancer patient, we established the CD4+ alpha beta Th1-like clone C27 that recognizes wild-type (3EYKLVVVGAGGVGKS17) and mutated p21 Ras protein molecules and peptides, in an HLA-DR1-restricted manner. C27 responded prominently to mutated Ras peptides carrying Val or Ala at position 12, as compared to wild-type and other mutated peptides. C27 also exhibited a much stronger response to a mutated p21 Ras whole-protein molecule-carrying Val at position 12, as compared with the wild-type protein. The proliferative response and production of GM-CSF, TNF-alpha, and IFN-gamma by C27 were further augmented by replacing the possible first DR anchor 4Tyr of the mutated Ras peptide with Trp, a more potent anchor residue for the DR1 molecule. Enhancement of peptide antigenicity by substituting the HLA anchor residue of an antigenic peptide recognized by tumor-reactive T-cells may prove to be a novel strategy for antigen-specific cancer immunotherapy.

Gene therapy for adult T cell leukemia using human immunodeficiency virus vector carrying the thymidine kinase gene of herpes simplex virus type 1

Adult T cell leukemia/lymphoma (ATL) is derived from CD4+ T cells and has a poor prognosis because of its resistance to chemotherapy. To evaluate the effectiveness of gene therapy for ATL, the effect of ganciclovir on ATL cell lines transfected with the thymidine kinase gene of herpes simplex virus type 1 (HSV-TK) was analyzed. To transfer the HSV-TK gene to ATL cells, a human immunodeficiency virus (HIV) vector that has specific infectivity to CD4+ cells was used. HSV-TK was inserted into the long terminal repeats of HIV-1 and driven by the SL3 promoter HXBSL3TK. HXBSL3TK was co-transfected with HXBCAT as a reporter into MT2 or HUT102 cells by DEAE-dextran. The cells were incubated with ganciclovir, and chloramphenicol acetyltransferase (CAT) activity was analyzed. The CAT activity of the MT2 cells and HUT102 cells transfected with HXBSL3TK decreased dose-dependently with ganciclovir. HXBSL3TK was also co-transfected into COS cells with an HIV-1 packaging vector that has gag, pol, and env driven by a cytomegalovirus promoter. The supernatant was transferred to MT2 cells or Raji cells and incubated with ganciclovir. Ninety percent of the MT2 cells transduced by HXBSL3TK and incubated with ganciclovir were killed, but Raji cells were not killed. In addition, HXBTK that expresses the HSV-TK gene and Tat gene driven by the LTR of HIV-1 was constructed. HXBTK had a higher expression of the HSV-TK gene and higher sensitivity to ganciclovir than did HXBSL3TK.

[Longevity, disease, and duration of disability]

Disability and the resulting lowered quality of life are serious issues accompanying increased longevity. Active life expectancy #(8) can be to used to distinguish the number of years without disability from the number with disability; increases were found in both in longevity #(9, 19). With the same rate of age-related new disability in the cohorts between 1970 and 1990, the total disability increased three fold #(11). In elderly patients I showed that 1) the duration of disability of those at a specific age at death (predeath) #(1) increased with age, and it decreased in those who remained without disability, 2) the cumulative number of days of disability for patients who died at a specific age (a convolution function of predeath and mortality) #(2), approached a normal distribution, which is consistent with the central limit theorem, 3) competing risk with chronic disease in a patient greatly affects the incidence and duration of disability, 4) using the central limit theorem we can predict that preventing dementia will retard premature rectangularization of the disability-free survival curve, and will thus reduce the total disability, 5) disability is an example of how variation and selection of chronic diseases (disease Darwinism) can alter population structure. Insights into the evolution of senescence #(14-21), pleiotropy, and slower rates of molecular evolution in the core than at the border #(26, 27), reveal that the central nervous system is relatively robust and conservative for pleiotropy and may senesce relatively slowly, which support a new way of thinking #(3, 4) about old age. To minimize disability, public knowledge and education about an ideal lifestyle and the evolution of senescence is essential.

Altered TCR ligands affect antigen-presenting cell responses: up-regulation of IL-12 by an analogue peptide

When examining the effects of analogue peptides on changes in response patterns of a human Th0 clone DT13.2 that recognizes a peptide fragment (18RSLRTVTPIRMQGG31) derived from a group I allergen in Dermatophagoides farinae in the context of HLA-DQ6 (DQA1*0102/DQB1*0602), we found that replacement of the 21st residue Arg to Lys resulted in a significant increase in IFN-gamma production, with no remarkable changes either in proliferative response or IL-4 production, at high doses of the peptide. Selective enhancement of IFN-gamma production by the analogue peptide was accompanied by an increased production of IL-12, which was suppressed by an anti-IL-12 Ab down to the level of IFN-gamma production induced by the wild-type peptide. On the contrary, co-incubation with neutralizing Abs to IFN-gamma and IFN-gamma receptor did not affect IL-12 production, indicating that increased production of IL-12 stimulated by the analogue peptide was not due to an effect of IFN-gamma from T cells. Peptide-induced up-regulation of CD40 ligand expression at high peptide concentrations showed no difference between the wild-type and analogue peptides. These data collectively indicate that certain T cell/APC interactions mediated through TCR and altered TCR ligands affect APC responses and that signals transmitted to APC are as indispensable as those to T cells in determining T cell response patterns.

Altered TCR ligands affect antigen-presenting cell responses: up-regulation of IL-12 by an analogue peptide

When examining the effects of analogue peptides on changes in response patterns of a human Th0 clone DT13.2 that recognizes a peptide fragment (18RSLRTVTPIRMQGG31) derived from a group I allergen in Dermatophagoides farinae in the context of HLA-DQ6 (DQA1*0102/DQB1*0602), we found that replacement of the 21st residue Arg to Lys resulted in a significant increase in IFN-gamma production, with no remarkable changes either in proliferative response or IL-4 production, at high doses of the peptide. Selective enhancement of IFN-gamma production by the analogue peptide was accompanied by an increased production of IL-12, which was suppressed by an anti-IL-12 Ab down to the level of IFN-gamma production induced by the wild-type peptide. On the contrary, co-incubation with neutralizing Abs to IFN-gamma and IFN-gamma receptor did not affect IL-12 production, indicating that increased production of IL-12 stimulated by the analogue peptide was not due to an effect of IFN-gamma from T cells. Peptide-induced up-regulation of CD40 ligand expression at high peptide concentrations showed no difference between the wild-type and analogue peptides. These data collectively indicate that certain T cell/APC interactions mediated through TCR and altered TCR ligands affect APC responses and that signals transmitted to APC are as indispensable as those to T cells in determining T cell response patterns.

Demonstration of rat CAR bacillus using a labelled streptavidin biotin (LSAB) method

Immunohistochemical detection of rat CAR bacillus antigen in paraffin-embedded experimentally infected rat lungs, using an immunoperoxidase technique based on the labelled streptavidin biotin (LSAB) method and 3-amino-9-ethylcarbazole (AEC) as substrate is described in this paper. The pattern of immunostaining was confined to the ciliated bronchial epithelium and the specificity of this technique was confirmed. The use of AEC as substrate was evaluated more efficient than diaminobenzidine (DAB). The usefulness of this immunoperoxidase technique for the detection of CAR bacillus in rats and its advantages compared to the indirect immunofluorescence (IF) are discussed.

Genotypes of alcohol-metabolizing enzymes and the risk for alcoholic chronic pancreatitis in Japanese alcoholics

Genetic predisposition to alcoholism and alcoholic liver disease has been reported. However, genetic susceptibility to alcoholic pancreatitis is still a matter of debate. To determine it, we examined genotype patterns of aldehyde dehydrogenase (ALDH2), alcohol dehydrogenase (ADH2 and ADH3), and cytochrome P-4502E1 (CYP2E1) in alcoholic pancreatitis patients. In 296 alcoholic patients, 52 cases showed findings of chronic pancreatitis by ultrasonography and x-ray computed tomography and/or had a history of pancreatitis (P+). The remaining 244 patients had neither abnormal findings of the image examinations nor a history of pancreatitis (P-). As for the ADH2 genotype, distribution of 2(1)/2(1), 2(1)/2(2), and 2(2)/2(2) was 22, 37, and 42% in P+ patients, whereas 34, 35, and 30% in P- patients, respectively. The frequency of ADH2(2)/2(2) genotype was significantly higher in P+ patients, compared with that in P- patients. There were no significant differences in the distribution of ADH3, ALDH2, and CYP2E1 genotypes between P+ and P- patients. In 14 alcoholic patients who showed low contents of fecal chymotrypsin, which suggests dysfunction of pancreatic exocrine, the rate of ADH2(2)/2(2) genotype also tended to be higher (50%) than in 74 controls who showed normal contents of the fecal chymotrypsin (28%). No differences were observed in genotypes of ADH3, ALDH2, and CYP2E1. Moreover, the frequency of ADH2(2)/2(2) genotype was significantly higher in autopsy cases with interlobular fibrosis in the pancreas, which suggests alcoholic pancreatic damage, than in cases with only intralobular pancreatic fibrosis. These data suggest that the risk of alcoholic pancreatitis seems to be associated with the presence of ADH2(2)/2(2) genotype.

Cancer screening of upper aerodigestive tract in Japanese alcoholics with reference to drinking and smoking habits and aldehyde dehydrogenase-2 genotype

In this study, 1,000 Japanese male alcoholics were consecutively screened by upper gastrointestinal endoscopy with esophageal iodine staining. Associations among cancer-detection rates, drinking and smoking habits, and aldehyde dehydrogenase-2 (ALDH2) genotypes were evaluated. A total of 53 patients (5.3%) had histologically confirmed cancer. Esophageal cancer was diagnosed in 36, gastric cancer in 17, and oropharyngolaryngeal cancer in 9 patients: 8 of the esophageal-cancer patients were multiple-cancer patients, with additional cancer(s) in the stomach and/or oropharyngolaryngeal region. Multiple logistic regression revealed that use of stronger alcoholic beverages (whisky or shochu) in contrast with lighter beverages (sake or beer) and smoking of 50 pack-years or more increased the risks for esophageal (odds ratio 3.2 and 2.8 respectively), oropharyngolaryngeal (4.8 and 5.1 respectively) and multiple cancer (10.5 and 11.8 respectively). The inactive form of ALDH2, encoded by the gene ALDH2*1/2*2 prevalent in Orientals, exposes them to higher blood levels of acetaldehyde, a recognized animal carcinogen, after drinking. This inactive ALDH2 was detected in 19/36 (52.8%) patients with esophageal cancer, in 5/9 (55.6%) patients with oropharyngolaryngeal cancer, and in 7/8 (87.5%) patients with multiple cancer. All of these gene frequencies far exceeded that in a large alcoholic cohort (80/655, 12.2%). The triple combination of the risk factors of the inactive ALDH2, stronger alcoholic beverages and heavy smoking was more commonly associated with multiple-cancer patients than with patients with esophageal cancer alone (62.5% vs. 7.1%). These results show that the 3 risk factors are important for the development of upper-aerodigestive-tract cancer in Japanese alcoholics. For these high-risk drinkers, regimented screening appears to be indicated.

Response of a human T cell clone to a large panel of altered peptide ligands carrying single residue substitutions in an antigenic peptide: characterization and frequencies of TCR agonism and TCR antagonism with or without partial activation

A CD4+ human T cell clone YN5-32 recognized a streptococcal M12p54-68 peptide in the context of HLA-DR4 and produced a large amount of IFN-gamma. We investigated responses of YN5-32 to 156 independent analogue peptides carrying single residue substitutions at residues 57 (position 1 (p1)) to 65 (p9) of the peptide. Approximately 30% of analogues at either Leu57 (p1), Ala60 (p4), or Asn62 (p6) residues exhibited TCR agonism to stimulate various magnitudes of proliferative responses in the T cell clone, and analogues exhibiting TCR antagonism are rare in these three residues. In analogues at either Glu58 (p2), Gln59 (p3), Tyr61 (p5), or Glu63 (p7) residue, 30 to 50% exhibited TCR antagonism. About 10% of analogues at Glu58 (p2) or Tyr61 (p5) stimulated proliferative responses, while 30 to 50% of analogues at Gln59 (p3) or Glu63 (p7) did so. Some of these TCR antagonistic analogues carrying relatively conservative amino acid substitutions partially activated the T cells to induce large increases in size and expression levels of CD4, CD11a (LFA-1), CD28, CD49d (VLA-4), and CD95 (Fas), and small increases in CD25 and CD44 expressions on the cell surface. None of the partially activating antagonistic analogues induced IFN-gamma production or anergy in T cells. Analogues with replacements of acidic amino acids at either Leu64 (p8) or Ser65 (p9) residue had dominant negative effects on T cell proliferation. Thus, altered peptide ligands with single residue substitutions in the antigenic peptide frequently stimulated the human T cell clone, in at least three different ways to exhibit agonism, antagonism, and antagonism with partial activation. Frequencies of analogue peptides exhibiting these three different effects on the T cell clone differed depending on the residue of the peptide substituted. Altered T cell responses induced by analogue peptides of a T cell epitope provide a system to analyze activation signals mediated by TCR, and to manipulate T cell responses.

Isolation and characterization of restriction endonuclease in Plesiomonas shigelloides and Aeromonas species

Five restriction endonucleases (ENases) and one ENase were found in a screen of 196 strains of Plesiomonas shigelloides and 147 strains of Aeromonas species. Plesiomonas and Aeromonas species are classified as Vibrionaceae, identified as food-poisoning bacteria, are closely genetically related to each other, and their ENases producing abilities have not bee reported. ENases were detected at relatively low frequencies in these species as compared to those in other species, such as Salmonella species and Vibrio parahaemolyticus. All Enases were shown to be isoschizomers of already known ENases. One of the Plesiomonas ENases, designated PshBI, recognizing the sequence 5'-AT/TAAT-3' should be useful, since PshBI ENase is produced at a high yield of 7000 units/g of wet cells. The specificities of other ENases are also described in this paper.

[Characteristics of Salmonella strains isolated from sporadic diarrheal cases during 1992-1994 in the Philippines]

A total of 263 Salmonella strains isolated in Metro Manila, the Philippines from 1992 to 1994, were examined for their serovar-distribution and drug-resistance. Salmonella serovar Typhi (S. Typhi) and S. Enteritidis phage type was also tested. The serological typing results showed that the strains were classified into 10 O-groups and 32 serovars. S. Weltevreden, S. Enteritidis, S. Typhi, S. Typhimurium, and S. Derby were predominant in the serovars identified. The drug-resistance test using nine drugs (CP, TC, SM, KM, ABPC, ST, NA, FOM, and NFLX) showed that 95 strains (36.1%) were resistant to any of the seven drugs except FOM and NFLX. The serovars of a high resistant rate were S. Ruiru (100%), S. Typhimurium (87.0%), S. Senftenberg (80.0%), S. Derby (66.7%), and S. Agona (50.0%). Drug-resistance patterns of the resistant strains varied to 21 types, and 80 of them were multidrug-resistant. Phage types of 37 S. Typhi strains were B1 (27 strains), E2 (6 strains), and others (4 strains). Phage types of 38 S. Enteritidis strains were 4 (32 strains), 7 (3 strains), and others (3 strains).

Response of a human T cell clone to a large panel of altered peptide ligands carrying single residue substitutions in an antigenic peptide: characterization and frequencies of TCR agonism and TCR antagonism with or without partial activation

A CD4+ human T cell clone YN5-32 recognized a streptococcal M12p54-68 peptide in the context of HLA-DR4 and produced a large amount of IFN-gamma. We investigated responses of YN5-32 to 156 independent analogue peptides carrying single residue substitutions at residues 57 (position 1 (p1)) to 65 (p9) of the peptide. Approximately 30% of analogues at either Leu57 (p1), Ala60 (p4), or Asn62 (p6) residues exhibited TCR agonism to stimulate various magnitudes of proliferative responses in the T cell clone, and analogues exhibiting TCR antagonism are rare in these three residues. In analogues at either Glu58 (p2), Gln59 (p3), Tyr61 (p5), or Glu63 (p7) residue, 30 to 50% exhibited TCR antagonism. About 10% of analogues at Glu58 (p2) or Tyr61 (p5) stimulated proliferative responses, while 30 to 50% of analogues at Gln59 (p3) or Glu63 (p7) did so. Some of these TCR antagonistic analogues carrying relatively conservative amino acid substitutions partially activated the T cells to induce large increases in size and expression levels of CD4, CD11a (LFA-1), CD28, CD49d (VLA-4), and CD95 (Fas), and small increases in CD25 and CD44 expressions on the cell surface. None of the partially activating antagonistic analogues induced IFN-gamma production or anergy in T cells. Analogues with replacements of acidic amino acids at either Leu64 (p8) or Ser65 (p9) residue had dominant negative effects on T cell proliferation. Thus, altered peptide ligands with single residue substitutions in the antigenic peptide frequently stimulated the human T cell clone, in at least three different ways to exhibit agonism, antagonism, and antagonism with partial activation. Frequencies of analogue peptides exhibiting these three different effects on the T cell clone differed depending on the residue of the peptide substituted. Altered T cell responses induced by analogue peptides of a T cell epitope provide a system to analyze activation signals mediated by TCR, and to manipulate T cell responses.

Western versus Asian types of multiple sclerosis: immunogenetically and clinically distinct disorders

The polymorphism of HLA-DRB1, -DRB3, and -DRB5 genes as well as magnetic resonance images of the brain and spinal cord were studied in 57 Japanese patients with multiple sclerosis (MS). Twenty-three patients clinically displayed selective involvement of the optic nerve and spinal cord and were classified as having Asian-type MS. The other 34 patients had disseminated central nervous system involvement and were classified as having Western-type MS. Patients with Asian-type MS had fewer brain lesions shown by magnetic resonance imaging, but more gadolinium-enhanced spinal cord lesions than did patients with Western-type MS (47% vs 17%). Furthermore, the DR2-associated DRB1*1501 allele and DRB5*0101 allele were associated with Western-type MS (41.2%), but not with either Asian-type MS (0%) or healthy control subjects (14.2%). Heterogeneity in the immunogenetic background and in the magnetic resonance imaging features between the two subtypes of MS thus suggests the presence of two etiologically distinct diseases in Asians.

Induction of apoptosis by calmodulin-dependent intracellular Ca2+ elevation in CD4+ cells expressing gp 160 of HIV

Human CD4+ cell clones expressing either gp160 or gp120 of HIV-1 under the transcriptional control of an inducible promoter were used to examine the role of Ca2+ signalling in the induction of apoptosis by envelope glycoproteins. Singlecell killing with apoptosis was induced in the cells expressing gp 160 while no such apoptosis was found in the cells expressing gp 120. An increase of intracellular Ca2+ was found in the gp 160-expressing cells but not in the gp 120-expressing cells as determined by Intracellular Ca2+ imaging analysis before the appearance of DNA fragmentation. W7, a calmodulin antagonist, blocked the elevation of Ca2+ as well as the resultant DNA fragmentation, which thus implies that the calmodulin-dependent intracellular Ca2+ release system is first activated by gp 160 and thereafter apoptosis takes place. The above results thus indicate that Ca2+ signalling plays a crucial role in the apoptosis accompanying the single-cell death induced by gp 160 in CD4+ cells.

Calcitonin gene-related peptide inhibits human platelet aggregation

Calcitonin gene-related peptide (CGRP) is a potent vasodilator in humans. CGRP receptors have also been found in various tissues other than blood vessels, such as the central nervous system, kidney, and heart. However, little is known about the effects of CGRP on human platelets. We investigated the effect of CGRP (human alpha type) on platelet aggregation in 21 healthy subjects (9 men and 12 women, mean age 54.6 years). CGRP inhibited platelet aggregation in vitro in 19 of the subjects (90.5%) in a dose-dependent manner with 50% inhibitory doses of 1.6 mumol/L and 1.1 mumol/L for aggregation induced by epinephrine and collagen, respectively. 125I-labeled CGRP bound specifically to intact platelets. The dissociation constant (Kd) was 61.9 +/- 17.7 pmol and the maximum number of binding sites (Bmax) was 5.4 +/- 3.9 pmol/10(9) platelets. The CGRP analogue (8-37)CGRP, but not calcitonin, inhibited the binding of 125I-CGRP to platelets. CGRP (5 mumol/L), but not (8-37)CGRP or calcitonin, increased the platelet cyclic AMP (cAMP) concentration by 31.7 +/- 3.6%. Thus, CGRP inhibits platelet aggregation via a specific receptor and by increasing the platelet cAMP concentration. CGRP may play a role in the modulation of platelet function in humans.

Dopamine D2, D3 and D4 receptor and transporter gene polymorphisms and mood disorders

Disturbances in dopaminergic systems have been implicated in the etiology of mood disorders. Although genetic factors also play an important role, no major gene has been identified. We conducted an association study using the dopamine D2, D3 and D4 receptor, and transporter gene polymorphisms, comparing 101 mood-disorder patients (52 bipolar and 49 unipolar) and 100 controls. Our results suggest that there is a significant association between the dopamine D4 receptor gene and mood disorders, especially major depression, but no association between the other polymorphisms and mood disorders. Further investigations are needed to clarify the clinical significance of this association in the pathophysiology of mood disorders.

Molecular mechanisms underlying HLA-DR-associated susceptibility to autoimmunity

We analyzed structural motifs of peptides bound to HLA-DR4 (DRB1*0405 and DRB1*0406) and DR9 (DRB1*0901) and found that: (a) AxxBxC motif where A, B, and C are hydrophobic, hydrophobic, and neutral, respectively, is important for binding to DR4; (b) Gln (Q) or Ser at position C allow high-affinity binding specific to DRB1*0406 which is strongly associated with insulin autoimmune syndrome; (c) among human insulin-derived peptide fragments, the TSICSLYQLE of the human insulin alpha chain, which is exposed only under reducing conditions, has the highest affinity specific to DRB1*0406 by binding with the IxxLxQ motif; (d) a short-term human insulin-specific T cell line recognizes a peptide fragment containing the IxxLxQ motif as a major T cell epitope; and (e) in the AxxB motif, where A and B need to be hydrophobic for binding to DR9, neutral Ser is exceptionally allowed at position B. The implications of our results are discussed in light of the HLA-DR4-associated susceptibility to insulin autoimmune syndrome and HLA-DR9-associated susceptibility to juvenile-onset myasthenia gravis and systemic lupus erythematosus with antiphospholipid syndrome, in particular T cell responses to autoantigens.