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NOTCH1 pathway activation contributes to the pathogenesis of over 60% of T-cell acute lymphoblastic leukemia (T-ALL). While Notch is thought to exert the majority of its effects through transcriptional activation of Myc, it also likely has independent roles in T-ALL malignancy. Here, we utilized a zebrafish transgenic model of T-ALL, where Notch does not induce Myc transcription, to identify a novel Notch gene expression signature that is also found in human T-ALL and is regulated independently of Myc. Cross-species microarray comparisons between zebrafish and mammalian disease identified a common T-ALL gene signature, suggesting that conserved genetic pathways underlie T-ALL development. Functionally, Notch expression induced a significant expansion of pre-leukemic clones; however, a majority of these clones were not fully transformed and could not induce leukemia when transplanted into recipient animals. Limiting-dilution cell transplantation revealed that Notch signaling does not increase the overall frequency of leukemia-propagating cells (LPCs), either alone or in collaboration with Myc. Taken together, these data indicate that a primary role of Notch signaling in T-ALL is to expand a population of pre-malignant thymocytes, of which a subset acquire the necessary mutations to become fully transformed LPCs.

Experimental autoimmune orchitis (EAO), the principal model of non-infectious testicular inflammatory disease, can be induced in susceptible mouse strains by immunization with autologous testicular homogenate and appropriate adjuvants. As previously established, the genome of DBA/2J mice encodes genes that are capable of conferring dominant resistance to EAO, while the genome of BALB/cByJ mice does not and they are therefore susceptible to EAO. In a genome scan, we previously identified Orch3 as the major quantitative trait locus controlling dominant resistance to EAO and mapped it to chromosome 11. Here, by utilizing a forward genetic approach, we identified kinesin family member 1C (Kif1c) as a positional candidate for Orch3 and, using a transgenic approach, demonstrated that Kif1c is Orch3. Mechanistically, we showed that the resistant Kif1c(D2) allele leads to a reduced antigen-specific T cell proliferative response as a consequence of decreased MHC class II expression by antigen presenting cells, and that the L(578) → P(578) and S(1027) → P(1027) polymorphisms distinguishing the BALB/cByJ and DBA/2J alleles, respectively, can play a role in transcriptional regulation. These findings may provide mechanistic insight into how polymorphism in other kinesins such as KIF21B and KIF5A influence susceptibility and resistance to human autoimmune diseases., Competing Interests: The authors have declared that no competing interests exist.

T-cell acute lymphoblastic leukemia (T-ALL) is a challenging clinical entity with high rates of induction failure and relapse. To discover the genetic changes occurring in T-ALL, and those contributing to relapse, we studied zebrafish (Danio rerio) T-ALL samples using array comparative genomic hybridization (aCGH). We performed aCGH on 17 T-ALLs from four zebrafish T-ALL models, and evaluated similarities between fish and humans by comparing all D. rerio genes with copy number aberrations (CNAs) with a cohort of 75 published human T-ALLs analyzed by aCGH. Within all D. rerio CNAs, we identified 893 genes with human homologues and found significant overlap (67%) with the human CNA dataset. In addition, when we restricted our analysis to primary T-ALLs (14 zebrafish and 61 human samples), 10 genes were recurrently altered in > 3 zebrafish cancers and ≥ 4 human cases, suggesting a conserved role for these loci in T-ALL transformation across species. We also conducted iterative allo-transplantation with three zebrafish malignancies. This technique selects for aggressive disease, resulting in shorter survival times in successive transplant rounds and modeling refractory and relapsed human T-ALL. Fifty-five percent of original CNAs were preserved after serial transplantation, demonstrating clonality between each primary and passaged leukemia. Cancers acquired an average of 34 new CNAs during passaging. Genes in these loci may underlie the enhanced malignant behavior of these neoplasias. We also compared genes from CNAs of passaged zebrafish malignancies with aCGH results from 50 human T-ALL patients who failed induction, relapsed or would eventually relapse. Again, many genes (88/164) were shared by both datasets. Further, nine recurrently altered genes in passaged D. rerio T-ALL were also found in multiple human T-ALL cases. These results suggest that zebrafish and human T-ALLs are similar at the genomic level, and are governed by factors that have persisted throughout evolution.

Translocations are key oncogenic events, and many rearrangements are characteristic for a specific malignancy. We present here a case of phenotypic precursor-B acute lymphoblastic leukemia (ALL), subsequently found to have both MYC and MLL translocations. Owing to the potential prognostic impact of these translocations, a novel treatment strategy was applied which merged precursor-B ALL, Burkitt-ALL, and "MLL-adapted" rationales. With the advent of expanding diagnostic panels and molecular therapeutic options, use of such adapted therapies for individualized treatment will undoubtedly continue to increase as we move toward pharmacogenomic-based approaches.

Importance of the Field: Pediatric acute lymphoblastic leukemia (ALL) represents one of the best examples of progress in disease treatment and improved outcome based in part upon the incorporation of the principles of pharmacogenomics. Throughout the past several decades, clinical scientists have continued to refine risk stratification in clinical trials with the understanding that individual patients have different subtypes of pediatric ALL that will respond to therapy in different, but predictable ways., Areas Covered in This Review: Discussed in this review are the most significant findings from pharmacogenomic studies of pediatric ALL from 1989 to the present. Pharmacogenomic studies related to the drugs commonly used to treat pediatric ALL are covered in detail, including an emphasis on both genome-wide and candidate gene/pathway approaches., What the Reader Will Gain: Readers of this paper will acquire a detailed understanding of how pharmacogenomic studies can be integrated into clinical trials, in addition to some of the discrepancies still present in the field., Take Home Message: The outcome for children with pediatric ALL has improved greatly, and this is in part due to the successful integration of data from pharmacogenomic studies into clinical trials.

Zebrafish (Danio rerio) has become an increasingly important model for immunological study. Its immune system is remarkably similar to that of mammals and includes both the adaptive and innate branches. Zebrafish T cells express functional T cell receptors (TCR), and all four TCR loci are present within the genome. Using 5'-rapid amplification of cDNA ends, we cloned and sequenced zebrafish TCRbeta transcripts. TCRbeta VDJ coding joints demonstrate conservation of mechanisms used by other vertebrate species to increase junctional diversity. Using the sequences obtained, along with previously published data, we comprehensively annotated the zebrafish TCRbeta locus. Overall, organization of the locus resembles that seen in mammals. There are 51 V segments, a single D segment, 27 Jbeta1 segments, a single Jbeta2 segment, and two constant regions. This description of the zebrafish TCRbeta locus has the potential to enhance immunological research in zebrafish and further our understanding of mammalian TCR repertoire generation.

T-cell neoplasias are common in pediatric oncology, and include acute lymphoblastic leukemia (T-ALL) and lymphoblastic lymphoma (T-LBL). These cancers have worse prognoses than their B-cell counterparts, and their treatments carry significant morbidity. Although many pediatric malignancies have characteristic translocations, most T-lymphocyte-derived diseases lack cytogenetic hallmarks. Lacking these informative lesions, insight into their molecular pathogenesis is less complete. Although dysregulation of the NOTCH1 pathway occurs in a substantial fraction of cases, many other genetic lesions of T-cell malignancy have not yet been determined. To address this deficiency, we pioneered a phenotype-driven forward-genetic screen in zebrafish (Danio rerio). Using transgenic fish with T-lymphocyte-specific expression of enhanced green fluorescent protein (EGFP), we performed chemical mutagenesis, screened animals for GFP(+) tumors, and identified multiple lines with a heritable predisposition to T-cell malignancy. In each line, the patterns of infiltration and morphological appearance resembled human T-ALL and T-LBL. T-cell receptor analyses confirmed their clonality. Malignancies were transplantable and contained leukemia-initiating cells, like their human correlates. In summary, we have identified multiple zebrafish mutants that recapitulate human T-cell neoplasia and show heritable transmission. These vertebrate models provide new genetic platforms for the study of these important human cancers.

The zebrafish has emerged as a powerful new vertebrate model of human disease. Initially prominent in developmental biology, the zebrafish has now been adopted into varied fields of study including immunology. In this review, we describe the characteristics of the zebrafish, which make it a versatile model, including a description of its immune system with its remarkable similarities to its mammalian counterparts. We review the zebrafish disease models of innate and adaptive immunity. Models of immune system malignancies are discussed that are either based on oncogene over-expression or on our own forward-genetic screen that was designed to identify new models of immune dysregulation.

Here we describe a method for the isolation of PCR-ready genomic DNA from various zebrafish tissues that is based on a previously published murine protocol. The DNA solutions are of sufficient quality to allow PCR detection of transgenes from all commonly used zebrafish tissues. In sperm, transgene amplification was successful even when diluted 1000-fold, allowing easy identification of transgenic founders. Given its speed and low cost, we anticipate that the adoption of this method will streamline DNA isolation for zebrafish research.

Anthrax lethal toxin (LT) is the principal virulence factor associated with lethal pathologies following infection with Bacillus anthracis. Macrophages are the primary effector cells mediating lethality since macrophage-depleted mice are resistant to LT challenge. Recently, Ltxs1, the gene controlling differential susceptibility of murine macrophages to cytolysis following in vitro exposure to LT, was identified as Kif1c. To directly assess the in vivo role of Kif1c alleles in mortality, we studied a panel of interval-specific recombinant congenic lines carrying various segments of central chromosome 11 derived from LT-resistant DBA/2 mice on the LT-susceptible BALB/c background. The results of this study reveal that mortality is controlled by three linked quantitative trait loci (QTL): Ltxs1/Kif1c (42-43 cM), Ltxs2 (35-37 cM), and Ltxs3 (45-47 cM). The Ltxs3 interval encompasses Nos2, which is an attractive candidate gene for Ltxs3. In this regard, we demonstrate that selective, pharmacologically based inhibition of Nos2 activity in vivo partially overrides genetic resistance to LT and that Nos2 expression as determined by reverse transcription-polymerase chain reaction differs significantly between DBA/2 and BALB/c macrophages. Additionally, to recapitulate dominant resistance to mortality as seen in (BALB/c x DBA/2) F(1) hybrids, DBA/2 alleles are required at all three QTL.

We report here the identification of three additional murine SmX5 alternative transcripts, designated SmX5a, b and c. The cDNA of SmX5a possesses intron 1 in its entirety, and SmX5b harbors a part of intron 2. The retained fragment of SmX5c starts at the same position as SmX5b, but the retention extends through the remaining portion of intron 2. The sequence of retained DNA at all the intron-exon boundaries conforms to the "GT-AG" rule. RT-PCR analysis indicates that the three isoforms are stable transcripts, all at low frequency when compared with SmX5. Expression analysis by RT-PCR indicates that SmX5 and its isoforms exist in murine brain, kidney, testis, thymus, liver, spleen and heart. The SmX5a isoform is predominantly expressed in the thymus, while SmX5b and c are expressed in all tissues examined. The presence of alternatively spliced SmX5 isoforms and tissue-specific variation in splicing patterns suggests that SmX5 expression is complex and that the regulation of all four SmX5 mRNA levels may be critical in maintaining proper pre-mRNA splicing machinery in different cell types.

In vivo intoxication with Bordetella pertussis toxin (PTX) elicits a variety of physiological responses including a marked leukocytosis, disruption of glucose regulation, adjuvant activity, alterations in vascular function, hypersensitivity to vasoactive agents, and death. We recently identified Bphs, the locus controlling PTX-induced hypersensitivity to the vasoactive amine histamine, as the histamine H(1) receptor (Hrh1). In this study Bphs congenic mice and mice with a disrupted Hrh1 gene were used to examine the role of Bphs/Hrh1 in the genetic control of susceptibility to a number of phenotypes elicited following in vivo intoxication. We report that the contribution of Bphs/Hrh1 to the overall genetic control of responsiveness to PTX is restricted to susceptibility to histamine hypersensitivity and enhancement of antigen-specific delayed-type hypersensitivity responses. Furthermore, the genetic contribution of Bphs/Hrh1 to vasoactive amine sensitization is specific for histamine, since hypersensitivity to serotonin was unaffected by Bphs/Hrh1. Bphs/Hrh1 also did not significantly influence susceptibility to the lethal effects, the leukocytosis response, disruption of glucose regulation, and histamine-independent increases in vascular permeability associated with in vivo intoxication. Nevertheless, significant interstrain differences in susceptibility to the lethal effects of PTX and leukocytosis response were observed. These results indicate that the phenotypic variation in responsiveness to PTX reflects the genetic control of distinct intermediate phenotypes rather than allelic variation in genes controlling overall susceptibility to intoxication.

Dapsone has been shown to be effective in treating adults with immune thrombocytopenic purpura (ITP). This retrospective review describes the authors' experience using dapsone in children with refractory, symptomatic ITP. Seven children were treated with dapsone. Dapsone was discontinued in two patients because of methemoglobinemia. In the remaining five patients, three achieved platelet counts of more than 100 x 10(3)/microL. Discontinuation resulted in a rapid decline in platelet counts in all three patients. Two of the three responded to a second round of treatment. Additional study of dapsone in children is warranted. Children receiving dapsone should be monitored for methemoglobinemia.

Bphs controls Bordetella pertussis toxin (PTX)-induced vasoactive amine sensitization elicited by histamine (VAASH) and has an established role in autoimmunity. We report that congenic mapping links Bphs to the histamine H1 receptor gene (Hrh1/H1R) and that H1R differs at three amino acid residues in VAASH-susceptible and -resistant mice. Hrh1-/- mice are protected from VAASH, which can be restored by genetic complementation with a susceptible Bphs/Hrh1 allele, and experimental allergic encephalomyelitis and autoimmune orchitis due to immune deviation. Thus, natural alleles of Hrh1 control both the autoimmune T cell and vascular responses regulated by histamine after PTX sensitization.

Pertussis toxin (PTX) is a potent ancillary adjuvant used to elicit several different autoimmune diseases, including experimental allergic encephalomyelitis (EAE). To delineate the genetics of PTX effect in EAE, we mapped EAE-modifying (eae-m) loci in cohorts of backcross mice immunized with and without PTX. In this study, we analyzed the genetic basis of EAE susceptibility and severity and the intermediate phenotypes of mononuclear cell infiltration, suppuration, and demyelination. In animals immunized with PTX, one major locus, eae9, controls disease susceptibility and severity. Eae9 also regulates the extent of mononuclear cell infiltration of the spinal cord in male mice. Without PTX, five eae-m loci were noted, including three new loci in intervals on chromosomes 8 (eae14), 10 (eae17), and 18 (eae18). Taken together, these results suggest that eae9 controls the effects of PTX in EAE susceptibility, and is capable of overriding the other genetic checkpoints in the pathogenesis of this disease.

An important approach to understanding complex diseases is to reduce them into well-characterized subphenotypes that are under monogenic control. One such example is Bordetella pertussis toxin-induced histamine sensitization in mice, a subphenotype of experimental allergic encephalomyelitis and experimental allergic orchitis. This subphenotype is controlled by a single locus, Bphs, previously mapped to a 33 cM region on mouse Chromosome (Chr) 6. We achieved considerable reduction of this candidate region and constructed a YAC contig across the refined interval. Our results demonstrate that Bphs is located between D6Mit151 and a newly developed marker, EC108RR, a region containing a small cluster of genes belonging to the TNF receptor superfamily. Sequence and quantitative analysis of the candidate gene, tumor necrosis factor receptor 1 (Tnfr1, p55), indicates that it is unlikely to be Bphs. However, the location of Bphs, together with physiologic effects it shares with Tnfr1 activation, suggest that Bphs may prove to be another member of the TNF receptor superfamily.

The existence of immunoregulatory genes conferring dominant resistance to autoimmunity is well documented. In an effort to better understand the nature and mechanisms of action of these genes, we utilized the murine model of autoimmune orchitis as a prototype. When the orchitis-resistant strain DBA/2J is crossed with the orchitis-susceptible strain BALB/cByJ, the F1 hybrid is completely resistant to the disease. By using reciprocal radiation bone marrow chimeras, the functional component mediating this resistance was mapped to the bone marrow-derived compartment. Resistance is not a function of either low-dose irradiation- or cyclophosphamide (20 mg/kg)-sensitive immunoregulatory cells, but can be adoptively transferred by primed splenocytes. Genome exclusion mapping identified three loci controlling the resistant phenotype. Orch3 maps to chromosome 11, whereas Orch4 and Orch5 map to the telomeric and centromeric regions of chromosome 1, respectively. All three genes are linked to a number of immunologically relevant candidate loci. Most significant, however, is the linkage of Orch3 to Idd4 and Orch5 to Idd5, two susceptibility genes which play a role in autoimmune insulin-dependent type 1 diabetes mellitus in the nonobese diabetic mouse.

Mice thymectomized at three days of age (D3Tx) develop during adulthood a variety of organ-specific autoimmune diseases, including autoimmune ovarian dysgenesis (AOD). The phenotypic spectrum of AOD is characterized by the development of anti-ovarian autoantibodies, oophoritis, and atrophy. The D3Tx model of AOD is unique in that disease induction depends exclusively on perturbation of the normal developing immune system, is T-cell-mediated, and is strain specific. For example, D3Tx A/J mice are highly susceptible to AOD, whereas C57BL/6J mice are resistant. After D3Tx, self ovarian antigens, expressed at physiological levels, trigger an autoimmune response capable of eliciting disease. The D3Tx model provides, therefore, the opportunity to focus on the mechanisms of self-tolerance that are relevant to disease pathogenesis. Previous studies indicate that the principal mechanisms involved in AOD susceptibility are genetically controlled and govern developmental processes associated with the induction and maintenance of peripheral tolerance. We report here the mapping of the Aod1 locus to mouse chromosome 16 within a region encoding several loci of immunologic relevance, including scid, Igl1, VpreB, Igll, Igl1r, Mtv6 (Mls-3), Ly-7, Ifnar, and Ifgt.

Experimental allergic orchitis (EAO) can be induced actively and passively in mice by either immunization with mouse testicular homogenate (MTH) in conjunction with the appropriate adjuvants or by transferring CD4+ T cells isolated from sensitized donors into non-immunized, naive recipients. The distribution of inflammatory lesions seen in active and passive EAO are markedly different. In active EAO maximal disease is observed in the seminiferous tubules, whereas in passive EAO lesions occur primarily in the straight tubules, rete testis, and ductus efferentes. These observations suggest that different immunopathogenic mechanisms and/or aspermatogenic autoantigens may be responsible for the distinct histopathologic profiles. Two murine testis-specific aspermatogenic autoantigens (mAP1 and mAP2) were partially purified from MT acetone powder by extraction in 7-M urea under reducing conditions, gel filtration, ion-exchange chromatography, and preparative isoelectric focusing from pH 3 to 10. In gel filtration on Sephacryl S-400 in 7-M urea, mAP1 is confined to the V0 peak, while mAP2 is in the major included peak. mAP1 has an isoelectric point of 4.4-4.9, is sensitive to both pronase and DNase but not RNase, and is active at a minimal dose of 250-500 micrograms (dry wt). Dose-response bioassays for active and passive EAO revealed that mAP1 preferentially elicits active disease, whereas mAP2 is most effective at eliciting passive disease. These results support the concept that the different histopathologic profiles seen in active and passive EAO are, in part, the result of different immunopathologic responses elicited by separate aspermatogenic autoantigens.

Experimental allergic orchitis is an organ-specific autoimmune disease characterized by inflammatory infiltrates associated with the seminiferous tubules of the testes. Orchitis is often, but not always, accompanied by aspermatogenesis in susceptible strains of mice. In this study, various strains of H-2 congenic mice were used to examine the relationship between orchitis and aspermatogenesis, and as a result, a genetic predisposition to spontaneous aspermatogenesis has been defined. A high correlation was seen between orchitis and aspermatogenesis in B10.D2/nSnJ mice, however, the two conditions were uncorrelated in C57BL/10J mice. Subsequent analysis of C57BL/10J congenic strains showed their aspermatogenesis to be spontaneous, rather than due to either testis-specific antigen or adjuvants. Further studies using other H-2 congenic strains revealed that the aspermatogenesis seen in C57BL/10J mice is linked to H-2 and influenced by C57BL/10J background genes. Finally, spontaneous aspermatogenesis was shown not to be a function of differences in the level of testicular testosterone.

Pertussis toxin (PTX) is the primary component responsible for eliciting the majority of biological activities associated with Bordetella pertussis, including the induction of several tissue-adjuvant models of organ-specific autoimmune disease. PTX, when administered in vivo, enhances vascular permeability, which is made manifest by a concomitant increase in sensitivity to a variety of agents and treatments affecting the vascular bed. One such agent is histamine, and the response to PTX, as measured by hypersensitivity following vasoactive amine challenge, is genetically controlled by the Bphs locus. Susceptibility to the induction of both experimental allergic encephalomyelitis (EAE) and experimental allergic orchitis (EAO) in mice is associated with, and in the latter case linked to, a susceptible allele at this locus. We report here the mapping of the Bphs locus to mouse chromosome 6, telomeric of Tcrb and centromeric of Prp (D6Nds8). This region also contains a number of loci of immunologic relevance including Igk, Ly-2, Ly-3, Il-5r, Ly-35, Ly-4, and Tnfr-2.

The polymerase chain reaction (PCR)-based technique of random amplification of polymorphic DNA (RAPD) is extremely useful for developing DNA-based markers. We previously identified a linkage group of eight unmapped RAPD markers that distinguish C57BL/6J and DBA/2J mice (Mammalian Genome 3: Woodward et al., 73-78, 1992). In this study, we report that all eight markers are Y Chromosome (Chr)-linked. One additional Y-linked RAPD was discovered serendipitously during the screening of a C3H/HeJ x (C3H/HeJ x SJL/J)F1 BC1 population. The segregation of all nine markers was analyzed with a panel of 14 independent inbred strains of male mice. The nine markers could be divided into three distinct groups: (1) DYByu2, DYByu5, DYByu6, and DYByu8 identify both the M.m. musculus and M.m. domesticus type Y Chr; (2) DYByu1, DYByu3, DYByu4, and DYByu7 are specific for the M.m. musculus type; and (3) DYByu9 is specific for the M.m. domesticus type. The results clearly indicate that the RAPD technique can be used to identify Y Chr-linked, DNA-based markers in mammalian species.