Moyamoya Disease Associated with a Deficiency of Complement Component 6.

OBJECTIVES: Complement component 6 (C6) deficiency is a very rare genetic defect that leads to significantly diminished synthesis, secretion, or function of C6. In the current report, we demonstrate a previously undescribed, homozygous missense mutation in exon 17 of the C6 gene (c.2545A>G p.Arg849Gly) in a 35-year-old Japanese woman with moyamoya disease and extremely low levels of CH50 (<7.0 U/mL). MATERIALS AND METHODS: The complement gene analysis using hybridization capture-based next generation sequencing was performed. CH50 was determined in patient's plasma mixed with plasma from a healthy donor or purified human C6 protein. Western blot was performed on patient's plasma using polyclonal antibodies against C6, with healthy donor's plasma and purified human C6 protein as positive controls while C6-depleted human serum as a negative control. The carriage of ring finger protein 213 variant (c.14576G>A p.Arg4859Lys), a susceptibility gene for moyamoya disease, was examined by direct sequencing. RESULTS: CH50 mixing test clearly showed a deficiency pattern, being rescued by addition of only 1% healthy donor's plasma or 1 µg/mL purified human C6 protein (1/50-1/100 of physiological concentration). Western blot revealed the absence of C6 protein in the patient's plasma, confirming a quantitative deficiency of C6. The ring finger protein 213 variant was not detected. CONCLUSIONS: Our data implies that unrecognized complement deficiencies would be harbored in cerebrovascular diseases with unknown etiologies.

Disseminated gonococcal infection in a Japanese man with complement 7 deficiency with compound heterozygous variants: A case report.

RATIONALE: Complement deficiency are known to be predisposed to disseminated gonococcal infection (DGI). We herein present a case of DGI involving a Japanese man who latently had a complement 7 deficiency with compound heterozygous variants. PATIENT CONCERNS: A previously healthy 51-year-old Japanese man complained of sudden-onset high fever. Physical examination revealed various skin lesions including red papules on his trunk and extremities, an impetigo-like pustule on left forearm, and tendinitis of his right forefinger. DIAGNOSIS: Blood culture testing detected gram-negative cocci, which was confirmed to be Neisseria gonorrhoeae based on mass spectrometry and a pathogen-specific PCR test. INTERVENTIONS: Screening tests for underlying immunocompromised factors uncovered that complement activities (CH50) was undetectable. With a suspicion of a congenital complement deficiency, genetic analysis revealed rare single nucleotide variants in complement 7 (C7), including c.281-1G>T and a novel variant c.1454C>T (p.A485V). CH50 was normally recovered by adding purified human C7 to the patient's serum, supporting that the patient has C7 deficiency with compound heterozygous variants. OUTCOMES: Under a diagnosis of DGI, the patient underwent an antibiotic treatment with cefotaxime for a week and was discharged without any sequela. LESSONS: DGI is a rare sexually-transmitted infection that potentially induces systemic complications. Complement immunity usually defeats N. gonorrhoeae and prevents the organism from causing DGI. This case highlighted the importance of suspecting a complement deficiency when a person develops DGI.

Proposed criterion for distinguishing ABO mosaics from ABO chimeras using flow cytometric analysis.

Differentiation of ABO mosaics from chimeras is performed using flow cytometry (FCM) analysis. Although mosaics and chimeras have been distinguished by presence or absence of clear resolution using FCM analysis, the lack of quantitative metrics and definitive criteria for this differentiation has made some cases difficult to differentiate. In this study, therefore, we attempted to establish a definitive and quantitative criterion for this differentiation. When FCM histogram gates for group "A" or "B" antigen-negative and -positive red blood cells (RBCs) were set such that group O RBCs were classified as 99 percent negative and group A or B RBCs as 99 percent positive, the percentages of RBCs in the middle region of six chimeras and 23 mosaics (12 A mosaics and 11 B mosaics) were 0.1-0.6 percent and 7.0-19.0 percent, respectively. This results suggested that ABO mosaics and chimeras can be unambiguously differentiated when the cutoff point of the intermediate region is set to 1 percent.

A case of neonatal alloimmune thrombocytopenia in the presence of both anti-HPA-4b and anti-HPA-5b antibody: clinical and serological analysis of the subsequent pregnancy.

Neonatal alloimmune thrombocytopenia (NAIT) is induced by maternal alloantibodies raised against fetal platelet antigens inherited from the paternal parent. In contrast to Caucasians, in Asians, predominantly in Japanese, most frequently detected antibodies in NAIT are anti-HPA-4b and anti-HPA-5b. In some NAIT cases multiple alloantibodies are detected. In such cases it is very difficult to determine which antibody is the dominant antibody in NAIT. In this case report, we describe a NAIT case (first sibling) with severe thrombocytopenia and cephalhematoma in the presence of both anti-HPA-4b and anti-HPA-5b antibodies in the maternal serum. We carefully examined titers of anti-HPA antibodies during the subsequent pregnancy with HPA-4b-positive and HPA-5b-negative fetus determined by amniocentesis at gestational week 16. We administered IVIG (1 g/kg/w) to the mother from gestational week 32 to 35. The mother subsequently delivered a second sibling with normal platelet count by cesarean section. Although we could not completely rule out the involvement of anti-HPA-4b, our findings suggested that anti-HPA-5b was implicated in the NAIT in the first sibling.

Detection of anti-human platelet antibodies against integrin α2ß1 using cell lines.

BACKGROUND: Antibodies against human platelet antigens (HPA) are a cause of thrombocytopenia. Detection of rare anti-HPA antibodies using platelet preparations is difficult and would be improved by an alternative method that does not require platelets. In the present study, we describe the establishment of cell lines that stably express specific HPA associated with integrin α2ß1 and the application of these cell lines for detecting anti-HPA-5a and anti-HPA-5b antibodies. MATERIALS AND METHODS: Complementary DNA of the integrin α2 variants HPA-5b, -13b and -18b were individually transfected into K562 cells using retroviral vectors. Expression of integrin α2 was confirmed by flow cytometric analysis, immunoprecipitation and western blotting analysis. To verify whether the cell line panel was suitable for clinical diagnosis, we analysed its properties using monoclonal antibody-specific immobilisation of platelet antigens (MAIPA) and well-characterised serum samples. RESULTS: Exogenous integrin α2 expression was observed in the transfected cells for over 6 months. The cell line panel specifically detected previously characterised anti-HPA-5a and anti-HPA-5b antisera. No reactivity was observed with control sera, including normal sera and HLA antisera. DISCUSSION: We successfully established a cell line panel to facilitate the sensitive and reliable detection of anti-HPA-5a and anti-HPA-5b antibodies.

Anti-CCR4 mAb selectively depletes effector-type FoxP3+CD4+ regulatory T cells, evoking antitumor immune responses in humans.

CD4(+) Treg cells expressing the transcription factor FOXP3 (forkhead box P3) are abundant in tumor tissues and appear to hinder the induction of effective antitumor immunity. A substantial number of T cells, including Treg cells, in tumor tissues and peripheral blood express C-C chemokine receptor 4 (CCR4). Here we show that CCR4 was specifically expressed by a subset of terminally differentiated and most suppressive CD45RA(-)FOXP3(hi)CD4(+) Treg cells [designated effector Treg (eTreg) cells], but not by CD45RA(+)FOXP3(lo)CD4(+) naive Treg cells, in peripheral blood of healthy individuals and cancer patients. In melanoma tissues, CCR4(+) eTreg cells were predominant among tumor-infiltrating FOXP3(+) T cells and much higher in frequency compared with those in peripheral blood. With peripheral blood lymphocytes from healthy individuals and melanoma patients, ex vivo depletion of CCR4(+) T cells and subsequent in vitro stimulation of the depleted cell population with the cancer/testis antigen NY-ESO-1 efficiently induced NY-ESO-1-specific CD4(+) T cells. Nondepletion failed in the induction. The magnitude of the responses was comparable with total removal of FOXP3(+) Treg cells by CD25(+) T-cell depletion. CCR4(+) T-cell depletion also augmented in vitro induction of NY-ESO-1-specific CD8(+) T cells in melanoma patients. Furthermore, in vivo administration of anti-CCR4 mAb markedly reduced the eTreg-cell fraction and augmented NY-ESO-1-specific CD8(+) T-cell responses in an adult T-cell leukemia-lymphoma patient whose leukemic cells expressed NY-ESO-1. Collectively, these findings indicate that anti-CCR4 mAb treatment is instrumental for evoking and augmenting antitumor immunity in cancer patients by selectively depleting eTreg cells.

Tax is a potential molecular target for immunotherapy of adult T-cell leukemia/lymphoma.

We expanded CTL specific for Tax (a human T-lymphotropic virus type-1-encoded gene product) in vitro from PBMC of several adult T-cell leukemia/lymphoma (ATL) patients, and document its potential significance as a target for ATL immunotherapy. Tax-specific CTL responses against tumor cells were restricted by Tax-expression and the appropriate human leukocyte antigen (HLA) type. Tax-specific CTL recognized HLA/Tax-peptide complexes on autologous ATL cells, even when their Tax expression was so low that it could only be detected by RT-PCR but not by flow cytometry. Recognition resulted in interferon gamma (IFN-γ) production and target cell lysis. This would be the first report that Tax-specific CTL from ATL patients specifically recognized and killed autologous tumor cells that expressed Tax. The Tax-specific CTL responded to as little as 0.01 pM of the corresponding peptide, indicating that their T-cell receptor avidity was much higher than that of any other CTL recognizing viral or other tumor antigens. This is presumably the reason why the Tax-specific CTL recognized and killed autologous ATL cells despite their very low Tax expression. In addition, cell cycle analyses and experiments with primary ATL cell-bearing mice demonstrated that ATL cells present at the site of active cell proliferation, such as in the tumor masses, expressed substantial amounts of Tax, but it was minimally expressed by the tumor cells in a quiescent state, such as in the blood. The present study not only provides a strong rationale for exploiting Tax as a possible target for ATL immunotherapy but also contributes to our understanding of the immunopathogenesis of ATL.

Cancer/testis antigens are novel targets of immunotherapy for adult T-cell leukemia/lymphoma.

Adult T-cell leukemia/lymphoma (ATLL) is an intractable hematologic malignancy caused by human T-lymphotropic virus type 1 (HTLV-1), which infects approximately 20 million people worldwide. Here, we have explored the possible expression of cancer/testis (CT) antigens by ATLL cells, as CT antigens are widely recognized as ideal targets of cancer immunotherapy against solid tumors. A high percentage (87.7%) of ATLL cases (n = 57) expressed CT antigens at the mRNA level: NY-ESO-1 (61.4%), MAGE-A3 (31.6%), and MAGE-A4 (61.4%). CT antigen expression was confirmed by immunohistochemistry. This contrasts with other types of lymphoma or leukemia, which scarcely express these CT antigens. Humoral immune responses, particularly against NY-ESO-1, were detected in 11.6% (5 of 43) and NY-ESO-1-specific CD8(+) T-cell responses were observed in 55.6% (5 of 9) of ATLL patients. NY-ESO-1-specific CD8(+) T cells recognized autologous ATLL cells and produced effector cytokines. Thus, ATLL cells characteristically express CT antigens and therefore vaccination with CT antigens can be an effective immunotherapy of ATLL.

The first two cases of neonatal alloimmune thrombocytopenia associated with the low-frequency platelet antigen HPA-21bw (Nos) in Japan.

BACKGROUND: Neonatal alloimmune thrombocytopenia (NAIT) is a disorder characterized by maternal alloimmunization against paternal fetal platelet antigens. Two healthy, unrelated Japanese women each gave birth to a child with severe NAIT. STUDY DESIGN AND METHODS: To elucidate the maternal causes of NAIT, we conducted serologic and genetic studies in these two NAIT infants. RESULTS: The serologic experiments localized the antigens to the glycoprotein (GP) IIIa subunit of the GPIIb/IIIa complex. Sequence-based typing studies subsequently identified a G>A mutation at Nucleotide 1960 (a glutamic acid > lysine substitution at Position 628) in the 11th exon of the GPIIIa gene. This mutation was recently identified in a report as HPA-21bw. Next, it was determined that the cause of NAIT in both cases was the HPA-21bw antigen, as shown by the mothers' antibodies reacting with the mutated GPIIIa-transfected cells, but not with transfectants expressing wild-type GPIIIa. A molecular genetic screening for the HPA-21bw allele among Japanese donors showed that its genetic frequency in the population was 0.53% (10/1888), indicating that HPA-21bw occurs at a low but appreciable frequency in the population. Furthermore, in a retrospective study of 50 previous NAIT cases of unknown causes, we found one NAIT case associated with the HPA-21bw antibody. The two NAIT cases in this study represent the first ones to be associated with HPA-21bw in Japan. CONCLUSION: We identified the HPA-21bw allele from two unrelated Japanese infants with severe NAIT. We identified 10 individuals (1.06%) positive for the HPA-21bw allele from a genetic screening of 944 Japanese blood donors.

Distribution of OCA2∗481Thr and OCA2∗615Arg, associated with hypopigmentation, in several additional populations.

Two mutants, OCA2∗481Thr (c.1441G>A, p.Ala481Thr) and OCA2∗615Arg (c.1844A>G, p.His615Arg), in the OCA2 (oculocutaneous albinism type II) gene are associated with hypopigmentation in East Asians. Here, these two alleles were studied to assess the frequencies in five different populations. In addition, the allele frequency of OCA2∗615Arg was investigated in seven populations. Among a total of 24 global populations investigated, Oroqens in Heihe showed the highest frequency for OCA2∗481Thr (0.519), and among 26 populations, Han Chinese in Changsha showed the highest frequency for OCA2∗615Arg (0.673). This study confirmed that these two East Asian-specific alleles are characteristic of northern and central-southern East Asian populations.

A hypervariable STR polymorphism in the complement factor I (CFI) gene: Asian-specific alleles.

In this study, a short tandem repeat (STR) polymorphism in intron 7 of the human complement factor I (CFI) gene was studied in 637 DNA samples obtained from African, German, Thai, and Japanese populations and German and Japanese families. A total of 41 alleles were observed and classified into two groups, L and H, based on size differences. Group H, which consisted of 16 alleles, was observed only in Thai and Japanese populations at frequencies of 0.162 and 0.116, respectively, and was strongly associated with c.1217A in exon 11 (CFI*Ah). The heterozygosity values ranged from 0.89 in German to 0.93 in Thai populations. This STR would be a useful supplementary marker for forensic individualization.

A Japanese-specific allele in the GALNT11 gene.

In this study, five single nucleotide polymorphisms (SNPs) in the ABCC4, FBN1, CEP152, ZNF804B, and GALNT11 genes were investigated to assess allele frequencies in 14 different populations by a novel pentaplex PCR method. All SNPs were polymorphic in East Asians, whereas mutant alleles were absent or rare in non-East Asians. The frequencies of a mutant allele in FBN1 (rs140598) showed a north-south downward cline in East Asia, whereas those of a mutant allele in ZNF804B (rs1916830) were relatively uniform in East Asia. The highest frequencies of mutant alleles in ABCC4 (rs3765534), CEP152 (rs2289178), and GALNT11 (rs3778922) were observed in Okinawa. The mutant allele in GALNT11 was found only in Far-East Asian populations: the frequencies were about 0.153 in Okinawa, 0.076 in the main island of Japan, and 0.017-0.004 in Korea. These five East Asian- and Japanese-specific SNPs would be useful markers for forensic individualization, in particular, as ancestry-informative markers.

Neonatal alloimmune thrombocytopenia caused by an antibody specific for a newly identified allele of human platelet antigen-7.

BACKGROUND: Neonatal alloimmune thrombocytopenia (NAIT) is a neonatal disorder characterized by maternal alloimmunization against fetal platelet (PLT) antigens inherited from the father. A healthy 30-year-old Japanese woman (Hit) gave birth to her second child after an uneventful pregnancy. Nine hours after birth, the infant presented with severe petechiae and a PLT count of 6 x 10(9)/L. STUDY DESIGN AND METHODS: To elucidate the maternal cause of NAIT in the infant, serologic and genetic studies, including PLT genotyping and sequence-based analysis, were conducted. Additionally, serologic screening for the new PLT antigen was performed. RESULTS: Serum from the NAIT infant's mother contained antibodies directed against a human PLT antigen (HPA) of the newborn. Using five-cell-lineage flow cytometry, we localized the antigen to a PLT glycoprotein (GP). Subsequent monoclonal antibody immobilization of PLT antigen assay and PLT immunofluorescence inhibition experiments localized the antigen to the GPIIIa subunit of the GPIIb/IIIa complex. GPIIIa localization was confirmed by sequence-based typing studies, which identified a 1297C>T (407proline>serine substitution) mutation on the ninth exon of the GPIIIa gene. This mutation identified the third allele of HPA-7. Anti-Hit(a) reacted with mutated GPIIIa-transfected cells but not with stable transfectants expressing wild-type GPIIIa. Serologic screening for Hit(a) in the Japanese population revealed a phenotypic frequency of approximately 0.0015. CONCLUSIONS: We identified a new third allele of HPA-7, which is characterized by a 1297C>T mutation in the GPIIIa gene. This 1297C>T allele was found in 0.15% of the Japanese population. An antibody against this antigen could be the cause of severe NAIT.

HERC1 polymorphisms: population-specific variations in haplotype composition.

Human HERC1 is one of six HERC proteins and may play an important role in intracellular membrane trafficking. The human HERC1 gene is suggested to have been affected by local positive selection. To assess the global frequency distributions of coding and non-coding single nucleotide polymorphisms (SNPs) in the HERC1 gene, we developed a new simultaneous genotyping method for four SNPs, and applied this method to investigate 1213 individuals from 12 global populations. The results confirmed remarked differences in the allele and haplotype frequencies between East Asian and non-East Asian populations. One of the three common haplotypes observed was found to be characteristic of East Asians, who showed a relatively uniform distribution of haplotypes. Information on haplotypes would be useful for testing the function of polymorphisms in the HERC1 gene. This is the first study to investigate the distribution of HERC1 polymorphisms in various populations.

Typing of the nt343C>T (R95X) allele of the C9 gene by PCR-SSP and the allele frequency of R95X in five ethnic populations.

One of the alleles which leads to ninth component of complement deficiency (C9D) is R95X (nt343C>T), which is present in most cases of C9D in Japan. In this study, we carried out nt343C>T typing by the method of polymerase chain reaction with sequence-specific primers (PCR-SSP), and showed the frequency of the R95X allele in German, Italian, Thai, Korean and Chinese populations. We did not find the R95X allele in the German or Italian populations. The allele frequency of R95X in the three Asian populations is as follows: Thais 0.019, Koreans 0.008, and Chinese 0.002. As the allele frequency in the Japanese population is 0.036, the results provide supporting evidence that the R95X is an allele characteristic of Japanese.

Haplotypes in the 5'-upstream region, exons 3 and 4, and introns 2 and 3 of the ABO blood group gene.

We previously described two haplotypes named the ABORR*L-associated and ABORR*S-associated haplotypes in the 5'-upstream region of the ABO blood group gene. Here we studied polymorphisms in exons (Exs) 3 and 4 and introns (Ints) 2 and 3 of the ABO gene, and analyzed the haplotypes in those Exs, Ints, and the 5'-upstream region. Two haplotypes (at Int2nt108-Int2nt362-Int2nt369-Int2nt539-Ex3nt106-Int3nt1178-Int3nt1357-Ex4nt188-Ex4nt189) were deduced to be (1) A-C-C-C-T-C-T-A-T, which was linked with ABORR*L and ABO*O(A), and (2) A-C-C-C-G-T-C-G-C, G-C-C-C-G-T-C-G-C, and A-T-G-A-G-T-C-G-C, which were linked with ABORR*S and the other common ABO alleles. This finding also shows the existence of two major lineages of the Japanese ABO alleles.

Rare alleles of the ABO blood group system in two European populations.

We performed genotyping of the ABO system in Italian and Israeli population samples. The nucleotides at 11 positions, nts 261, 297, 467, 526, 646, 681, 703, 796, 802, 803 and 1060, were analyzed by PCR-RFLP, PCR-SSP and PCR direct sequencing methods. We found three rare ABO alleles besides the common alleles (*)A1(Pro) (=(*)A101), (*)A2(Leu) (=(*)A201), (*)B (=(*)B101), (*)O(T) (=(*)O01), (*)O(A) (=(*)O02) and (*)O2 (=(*)O03), but did not detect ( *)A1(Leu) (=( *)A102) which is a common allele in Asians. The rare alleles were tentatively named (*)Ov1, (*)Ov2, and (*)Bv. As ( *)Bv has been found in two Japanese individuals and (*)O2 is not a rare ABO allele in Europeans, not only (*)O2 but also the (*)Ov1 and (*)Ov2 alleles may be characteristic of European populations.

Molecular basis of complement factor I (CFI) polymorphism: one of two polymorphic suballeles responsible for CFI A is Japanese-specific.

Isoelectric focusing has revealed that human complement factor I (CFI) is controlled by two polymorphic alleles, CFI(*)A and CFI(*)B, and a few rare variant alleles. In this study the molecular basis of the CFI polymorphism was investigated in 174 Japanese. The CFI(*)A was divided into two suballeles, CFI(*)As (R201S) and CFI(*)Ah (R406H). CFI(*)Aj, a rare variant allele originating from CFI(*)Ah, had an additional mutation (R502L). The distribution of these three mutations and two registered SNPs was investigated in a total of 2,471 individuals in 20 populations from various areas, and six haplotypes were observed. Haplotype H3, which is characterized by CFI(*)As, was found only in Far East populations: the frequencies were about 0.03 in the main island of Japan and lower than 0.01 in Okinawa and Korea. Haplotype H5, characterized by CFI(*)Ah, prevailed almost exclusively in East Asians and was observed at the highest frequencies in southern Chinese Han and Thais. CFI(*)Ah must have arisen in a southeastern part of Asia and thereafter have spread to neighboring populations.