Strong association of the HLA-DP6 supertype with childhood leukaemia is due to a single allele, DPB1*0601

Kikuchi disease in acute leukaemia: a distinct clinical syndrome with HLA association

AIMS

To report the clinicopathological features of Kikuchi disease in patients with acute leukaemia, emphasising similarities among cases.

METHODS AND RESULTS

In a cohort of 454 Kikuchi disease patients, we identified three cases of concurrent acute leukaemia. These patients shared similar clinical traits, with Kikuchi disease emerging approximately a month after induction chemotherapy onset, featuring neck-region lymphadenopathy. Notably, two patients were middle-aged, deviating from the typical age distribution of Kikuchi disease. Histologically, these cases aligned with typical Kikuchi disease. Negative immunohistochemical stains (CD34, CD117, ERG, TdT) indicated the absence of extramedullary leukaemic infiltration. Herpes simplex virus immunohistochemical staining was also negative. Significantly, a human leucocyte antigen (HLA) association was observed in these three cases. HLA-B*15:01, C*04:01, and DRB1*04:06 were more prevalent in these patients compared to the general population (compared with three independent control cohorts: Taiwanese Han Chinese (n = 504), Tzu Chi Taiwanese bone marrow donors (n = 364) and Hong Kong Chinese (n = 5266)).

CONCLUSIONS

Our study underscores the unique link between Kikuchi disease and acute leukaemia, characterised by specific features and HLA associations. This underlines Kikuchi disease as a possible differential diagnosis in pertinent clinical scenarios. Furthermore, this syndrome offers insights into postchemotherapy immunology in acute leukaemia, enhancing comprehension.

Preexisting and Post-COVID-19 Immune Responses to SARS-CoV-2 in Patients with Cancer

Patients with cancer, in particular patients with hematologic malignancies, are at increased risk for critical illness upon COVID-19. We here assessed antibody as well as CD4⁺ and CD8⁺ T-cell responses in unexposed and SARS-CoV-2-infected patients with cancer to characterize SARS-CoV-2 immunity and to identify immunologic parameters contributing to COVID-19 outcome. Unexposed patients with hematologic malignancies presented with reduced prevalence of preexisting SARS-CoV-2 cross-reactive CD4⁺ T-cell responses and signs of T-cell exhaustion compared with patients with solid tumors and healthy volunteers. Whereas SARS-CoV-2 antibody responses did not differ between patients with COVID-19 and cancer and healthy volunteers, intensity, expandability, and diversity of SARS-CoV-2 T-cell responses were profoundly reduced in patients with cancer, and the latter associated with a severe course of COVID-19. This identifies impaired SARS-CoV-2 T-cell immunity as a potential determinant for dismal outcome of COVID-19 in patients with cancer. SIGNIFICANCE: This first comprehensive analysis of SARS-CoV-2 immune responses in patients with cancer reports on the potential implications of impaired SARS-CoV-2 T-cell responses for understanding pathophysiology and predicting severity of COVID-19, which in turn might allow for the development of therapeutic measures and vaccines for this vulnerable patient population.See related commentary by Salomé and Horowitz, p. 1877.This article is highlighted in the In This Issue feature, p. 1861.

Genetic variants in HLA-DP/DQ contribute to risk of acute myeloid leukemia: A case-control study in Chinese

Human leukocyte antigens (HLA) are heterodimeric cell surface molecules that bind short peptides derived from non-self and self proteins. Accumulative evidence showed that specific alleles of HLA class II were associated with the susceptibility to malignant tumors including acute leukemia. In this study, we investigated the association between four single nucleotide polymorphisms (SNPs) at HLA-DP/DQ and acute myeloid leukemia (AML) risk. We genotyped four SNPs in HLA-DP (rs3077 G > A and rs9277535 G > A) and HLA-DQ (rs2856718 A > G and rs7453920 G > A) in a case-control study of 545 AML cases and 1034 cancer-free controls using Taqman allelic discrimination assay. The associations between these SNPs and AML risk were estimated by computing the odds ratios (ORs) and their 95% confidence intervals (CIs) from multivariate logistic regression analysis. We found significant associations of the variant alleles in HLA-DP (rs3077 and rs9277535) and HLA-DQ rs7453920 with increased AML risk (adjusted OR = 1.29, 95%CI = 1.10-1.51for rs3077 in additive model; adjusted OR = 1.29, 95%CI = 1.11-1.51 for rs9277535 in additive model; adjusted OR = 3.18, 95%CI = 1.86-5.46 for rs7453920 in recessive model). When combining the effects of rs3077, rs9277535 and rs7453920, we found that AML risk was significantly increased with the increasing number of variant alleles of the three SNPs in a dose-dependent manner (P for trend < 0.001). Besides, we found multiplicative interaction between rs3077 and age (≤45 years old and > 45 years old; P = 0.046). In conclusion, HLA-DP and HLA-DQ loci are candidate susceptibility regions for AML in Han Chinese.

The association between HLA and non-Hodgkin lymphoma subtypes, among a transplant-indicated population

Several studies have implicated HLA in non-Hodgkin lymphoma (NHL) subtype etiology. However, NHL patients indicated for stem cell transplants are underrepresented in these reports. We therefore evaluated the association between HLA and NHL subtypes among a transplant-indicated population. One thousand three hundred and sixty-six NHL patients HLA-typed and indicated for transplant at the City of Hope National Medical Center (Duarte, CA) were compared to 10,271 prospective donors. Odds ratios and 95% confidence intervals were calculated for HLA haplotype and alleles, adjusted for sex and age. The HLA-A*0201∼C*0602∼B*1302∼DRB1*0701∼DQB1*0201 haplotype was significantly associated with follicular lymphoma (FL) risk among Caucasians. Several haplotypes were associated with diffuse large B-cell lymphoma (DLBCL) risk among Caucasians, including the previously implicated DLBCL risk loci, HLA-B*0801. The HLA-A*0101 allele was also observed to be associated with mantle cell lymphoma (MCL) risk. Our results support the association between previously reported susceptibility loci and FL and suggest potentially new DLBCL and MCL risk loci.

Bone marrow T helper cells with a Th1 phenotype induce activation and proliferation of leukemic cells in precursor B acute lymphoblastic leukemia patients

Precursor B cell acute lymphoblastic leukemia (BCP-ALL) constitutes the leading cause of cancer-related death in children. While chromosomal alterations contribute to BCP-ALL pathogenesis, they are insufficient for leukemia development. Epidemiological data and evidence from a mouse model suggest that immune responses to infections may trigger the emergence of leukemia, but the mechanisms remain unclear. Here, we show that T helper (Th) cells from bone marrow of pediatric BCP-ALL patients can be attracted and activated by autologous BCP-ALL cells. Bone-marrow Th cells supportively interacted with BCP-ALL cells, inducing upregulation of important surface molecules and BCP-ALL cell proliferation. These Th cells displayed a Th1-like phenotype and produced high levels of IFN-γ. IFN-γ was responsible for the upregulation of CD38 in BCP-ALL cells, a molecule which we found to be associated with early relapse, and accountable for the production of IP-10, a chemokine involved in BCP-ALL migration and drug resistance. Thus, our data provide mechanistic support for an involvement of Th cell immune responses in the propagation of BCP-ALL and suggest that BCP-ALL cell-supportive Th cells may serve as therapeutic target.

A causal mechanism for childhood acute lymphoblastic leukaemia

In this Review, I present evidence supporting a multifactorial causation of childhood acute lymphoblastic leukaemia (ALL), a major subtype of paediatric cancer. ALL evolves in two discrete steps. First, in utero initiation by fusion gene formation or hyperdiploidy generates a covert, pre-leukaemic clone. Second, in a small fraction of these cases, the postnatal acquisition of secondary genetic changes (primarily V(D)J recombination-activating protein (RAG) and activation-induced cytidine deaminase (AID)-driven copy number alterations in the case of ETS translocation variant 6 (ETV6)-runt-related transcription factor 1 (RUNX1)+ ALL) drives conversion to overt leukaemia. Epidemiological and modelling studies endorse a dual role for common infections. Microbial exposures earlier in life are protective but, in their absence, later infections trigger the critical secondary mutations. Risk is further modified by inherited genetics, chance and, probably, diet. Childhood ALL can be viewed as a paradoxical consequence of progress in modern societies, where behavioural changes have restrained early microbial exposure. This engenders an evolutionary mismatch between historical adaptations of the immune system and contemporary lifestyles. Childhood ALL may be a preventable cancer.

Genome-wide association study identifies susceptibility loci for B-cell childhood acute lymphoblastic leukemia

Genome-wide association studies (GWAS) have advanced our understanding of susceptibility to B-cell precursor acute lymphoblastic leukemia (BCP-ALL); however, much of the heritable risk remains unidentified. Here, we perform a GWAS and conduct a meta-analysis with two existing GWAS, totaling 2442 cases and 14,609 controls. We identify risk loci for BCP-ALL at 8q24.21 (rs28665337, P = 3.86 × 10-9, odds ratio (OR) = 1.34) and for ETV6-RUNX1 fusion-positive BCP-ALL at 2q22.3 (rs17481869, P = 3.20 × 10-8, OR = 2.14). Our findings provide further insights into genetic susceptibility to ALL and its biology.

Pediatric precursor B acute lymphoblastic leukemia: are T helper cells the missing link in the infectious etiology theory?

Precursor B acute lymphoblastic leukemia (BCP-ALL), the most common childhood malignancy, arises from an expansion of malignant B cell precursors in the bone marrow. Epidemiological studies suggest that infections or immune responses to infections may promote such an expansion and thus BCP-ALL development. Nevertheless, a specific pathogen responsible for this process has not been identified. BCP-ALL cells critically depend on interactions with the bone marrow microenvironment. The bone marrow is also home to memory T helper (Th) cells that have previously expanded during an immune response in the periphery. In secondary lymphoid organs, Th cells can interact with malignant cells of mature B cell origin, while such interactions between Th cells and malignant immature B cell in the bone marrow have not been described yet. Nevertheless, literature supports a model where Th cells—expanded during an infection in early childhood—migrate to the bone marrow and support BCP-ALL cells as they support normal B cells. Further research is required to mechanistically confirm this model and to elucidate the interaction pathways between leukemia cells and cells of the tumor microenvironment. As benefit, targeting these interactions could be included in current treatment regimens to increase therapeutic efficiency and to reduce relapses.

Acute myeloid leukemia is a disease associated with HLA-C3

BACKGROUND

We aimed to observe human leukocyte antigen (HLA) associations with human acute myeloid leukemia (AML) in a large population, in order to investigate the roles of HLA in leukemogenesis. Furthermore, we examined the HLA association according to morphological, cytogenetic, immunological, and clinical classifications.

MATERIALS AND METHODS

We performed HLA genotyping, bone marrow studies, cytogenetic analyses, and fluorescence-activated cell sorting analyses. A clinical outcome database was constructed, and the HLA frequency, gene frequency, relative risk (RR), linkage disequilibrium, and the 2-locus and 3-locus haplotype frequency using the Mattiuz formula were calculated. For the healthy controls, Korean HLA data published by Park and co-workers were used.

RESULTS

AML was found to be associated with HLA-C3 (RR = 1.46; p < 0.001). In the French-American-British (FAB) classification, acute myelomonocytic leukemia (AML-M4) was associated with HLA-C3 (47.2 vs. 74.1%; RR = 3.13; p = 0.005), in cytogenetic classification, del(9), which is frequently observed in AML-M4, was also associated with HLA-C3 (47.2 vs. 100%; RR = 13.43; p = 0.024), and in clinical classification, incomplete remission was associated with HLA-C3 as well (47.2 vs. 63.2%; RR = 1.92; p = 0.002). No correlations between AML and immunological classifications were observed. Moreover, and in terms of 2-locus haplotypes, AML was found to be associated with HLA-C3/B62 (HLA-C3 gene frequency 0.3415; HLA-B62 gene frequency 0.1361; linkage disequilibrium 0.0136; haplotype frequency 4.15 vs. 6.0%; p < 0.05). In clinical classification, incomplete remission (linkage disequilibrium 0.0136; haplotype frequency 4.15 vs. 13.6%; p = 0.013) and relapse (linkage disequilibrium 0.0136; haplotype frequency 4.15 vs. 71.0%; p = 0.044) were associated with HLA-C3/B62, whereas no association was observed for FAB, cytogenetic and immunological classifications. No association was observed for the 3-locus haplotype.

CONCLUSION

The HLA-C3 antigen and the 2-locus haplotype are associated with AML.

Differences in meiotic recombination rates in childhood acute lymphoblastic leukemia at an MHC class II hotspot close to disease associated haplotypes

Childhood Acute Lymphoblastic Leukemia (ALL) is a malignant lymphoid disease of which B-cell precursor- (BCP) and T-cell- (T) ALL are subtypes. The role of alleles encoded by major histocompatibility loci (MHC) have been examined in a number of previous studies and results indicating weak, multi-allele associations between the HLA-DPB1 locus and BCP-ALL suggested a role for immunosusceptibility and possibly infection. Two independent SNP association studies of ALL identified loci approximately 37 kb from one another and flanking a strong meiotic recombination hotspot (DNA3), adjacent to HLA-DOA and centromeric of HLA-DPB1. To determine the relationship between this observation and HLA-DPB1 associations, we constructed high density SNP haplotypes of the 316 kb region from HLA-DMB to COL11A2 in childhood ALL and controls using a UK GWAS data subset and the software PHASE. Of four haplotype blocks identified, predicted haplotypes in Block 1 (centromeric of DNA3) differed significantly between BCP-ALL and controls (P = 0.002) and in Block 4 (including HLA-DPB1) between T-ALL and controls (P = 0.049). Of specific common (>5%) haplotypes in Block 1, two were less frequent in BCP-ALL, and in Block 4 a single haplotype was more frequent in T-ALL, compared to controls. Unexpectedly, we also observed apparent differences in ancestral meiotic recombination rates at DNA3, with BCP-ALL showing increased and T-ALL decreased levels compared to controls. In silico analysis using LDsplit sotware indicated that recombination rates at DNA3 are influenced by flanking loci, including SNPs identified in childhood ALL association studies. The observed differences in rates of meiotic recombination at this hotspot, and potentially others, may be a characteristic of childhood leukemia and contribute to disease susceptibility, alternatively they may reflect interactions between ALL-associated haplotypes in this region.

Genetic variation in the extended major histocompatibility complex and susceptibility to childhood acute lymphoblastic leukemia: a review of the evidence

The enduring suspicion that infections and immunologic response may play a role in the etiology of childhood leukemia, particularly acute lymphoblastic leukemia (ALL), is now supported, albeit still indirectly, by numerous epidemiological studies. The cumulative evidence includes, for example, descriptive observations of a peculiar peak incidence at age 2–5 years for ALL in economically developed countries, clustering of cases in situations of population mixing associated with unusual patterns of personal contacts, associations with various proxy measures for immune modulatory exposures early in life, and genetic susceptibility conferred by variation in genes involved in the immune system. In this review, our focus is the extended major histocompatibility complex (MHC), an approximately 7.6 Mb region that is well-known for its high-density of expressed genes, extensive polymorphisms exhibiting complex linkage disequilibrium patterns, and its disproportionately large number of immune-related genes, including human leukocyte antigen (HLA). First discovered through the role they play in transplant rejection, the classical HLA class I (HLA-A, -B, and -C) and class II (HLA-DR, HLA-DQ, and HLA-DP) molecules reside at the epicenter of the immune response pathways and are now the targets of many disease susceptibility studies, including those for childhood leukemia. The genes encoding the HLA molecules are only a minority of the over 250 expressed genes in the xMHC, and a growing number of studies are beginning to evaluate other loci through targeted investigations or utilizing a mapping approach with a comprehensive screen of the entire region. Here, we review the current epidemiologic evidence available to date regarding genetic variation contained within this highly unique region of the genome and its relationship with childhood ALL risk.

HLA-DPβ1 Asp84-Lys69 antigen-binding signature predicts event-free survival in childhood B-cell precursor acute lymphoblastic leukaemia: results from the MRC UKALL XI childhood ALL trial

We previously reported that children in the UKALL XI ALL trial with HLA-DP 1 and -DP 3 supertypes had significantly worse event-free survival (EFS) than children with other DP supertypes. As DP 1 and DP 3 share two of four key antigen-binding amino-acid polymorphisms (aspartic acid84–lysine69), we asked whether Asp84-Lys69 or Asp84 alone were independent prognostic indicators in childhood acute lymphoblastic leukemia (ALL). We analysed EFS in 798 UKALL XI patients, stratified by Asp84-Lys69 vs non-Asp84-Lys69, for a median follow-up of 12.5 years. Asp84-Lys69 was associated with a significantly worse EFS than non-Asp84-Lys69 (5-year EFS: Asp84-Lys69: 58.8% (95% CI (confidence of interval): 52.7–64.9%); non-Asp84-Lys69: 67.3% (63.4–71.2%); 2P=0.007). Post-relapse EFS was 10% less in Asp84-Lys69 than non-Asp84-Lys69 patients. EFS was significantly worse (P=0.03) and post-relapse EFS marginally worse (P=0.06) in patients with Asp84 compared with Gly84. These results suggest that Asp84-Lys69 predicted adverse EFS in the context of UKALL XI because of Asp84, and may have influenced post-relapse EFS. We speculate that this may be due to the recruitment of Asp84-Lys69-restricted regulatory T cells in the context of this regimen, leading to the re-emergence of residual disease. However, functional and molecular studies of the prognostic value of this and other HLA molecular signatures in other childhood ALL trials are needed.

Perspectives on the causes of childhood leukemia

Acute leukemia is the most common cancer in children but the causes of the disease in the majority of cases are not known. About 80% are precursor-B cell in origin (CD19+, CD10+), and this immunophenotype has increased in incidence over the past several decades in the Western world. Part of this increase may be due to the introduction of new chemical exposures into the child's environment including parental smoking, pesticides, traffic fumes, paint and household chemicals. However, much of the increase in leukemia rates is likely linked to altered patterns of infection during early childhood development, mirroring causal pathways responsible for a similarly increased incidence of other childhood-diagnosed immune-related illnesses including allergy, asthma, and type 1 diabetes. Factors linked to childhood leukemia that are likely surrogates for immune stimulation include exposure to childcare settings, parity status and birth order, vaccination history, and population mixing. In case-control studies, acute lymphoblastic leukemia (ALL) is consistently inversely associated with greater exposure to infections, via daycare and later birth order. New evidence suggests also that children who contract leukemia may harbor a congenital defect in immune responder status, as indicated by lower levels of the immunosuppressive cytokine IL-10 at birth in children who grow up to contract leukemia, as well as higher need for clinical care for infections within the first year of life despite having lower levels of exposure to infections. One manifestation of this phenomenon may be leukemia clusters which tend to appear as a leukemia "outbreak" among populations with low herd immunity to a new infection. Critical answers to the etiology of childhood leukemia will require incorporating new tools into traditional epidemiologic approaches - including the classification of leukemia at a molecular scale, better exposure assessments at all points in a child's life, a comprehensive understanding of genetic risk factors, and an appraisal of the interplay between infectious exposures and the status of immune response in individuals.

Association between HLA-DQB1 gene and patients with acute lymphoblastic leukemia (ALL)

Acute lymphoblastic leukemia (ALL) affects both children and adults. Survival in ALL has improved in recent decades due to recognition of its biological heterogeneity. Although children have higher remission and cure rates than adults, both populations have benefited from these improvements. Our aim in this study is to determine the association between HLA-DQB1 genes with childhood and adult ALL patients. To define this association, we compared HLA-DQB1 allele frequencies and allele carrier frequencies in a cohort of 135 adults and children with ALL with 150 controls, using polymerase chain reaction with sequence-specific primers. Allele carrier frequencies in childhood ALL show a deficiency in DQ2 (*0201) (P 0.049 and RR 0.75), but an increase in DQ5 (*0501-*0504) and DQ7 (*0301, *0304) compared to the control group (P 0.001 RR 1.89, P 0.003 RR 1.48, respectively). Allele carrier frequencies in adult ALL indicated an increase in DQ5 (*0501-*0504) (P0.045 RR 2.28). Allelic frequencies in childhood ALL revealed the same increase in DQ5 and DQ7, and a decrease in DQ2. In adult ALL it shows a decrease in DQ7. Therefore, our results in adult ALL were similar to childhood ALL addressing DQ5 allele carriers, which showed an increase in both age groups. We suggest that DQ5 could be more strongly considered as an ALL susceptibility allele, and that this allele may underlie a pathogenic phenotype with a major role in the immunologic process involved in both adults and children with ALL.

Transmission of HLA-DP variants from parents to children with B-cell precursor acute lymphoblastic leukemia: log-linear analysis using the case-parent design

Childhood B-cell precursor acute lymphoblastic leukemia (BCP ALL) is usually initiated in utero and is thought to progress to overt leukemia under the influence of delayed exposure to a common infection. Based on the hypothesis that polymorphic HLA-DP variants can restrict T-cell responses to infection, we previously compared DP supertype frequencies in BCP ALL patients with that of unrelated newborn controls. We reported that the DP2 supertype was associated with susceptibility, whereas DP1 was associated with protection. However, the association of genetic variants in children with early-onset diseases such as ALL may be a proxy for parental effects. Here we examine whether maternal DP1 and DP2 are associated with BCP ALL by fitting log-linear models in a combined series of family triads (both parents and case child) and dyads (1 parent and case child; n = 571) in comparison with similar models in non-BCP leukemia (n = 198). We report no evidence of maternal DP1 or DP2 associations with BCP ALL, but we did identify suggestive evidence of maternal undertransmission of the infrequent supertypes DP11 and DP15. Although these results require confirmation, they suggest that DP11 and DP15 may be protective or that there is transmission ratio distortion of these supertypes in BCP ALL.

MHC variation and risk of childhood B-cell precursor acute lymphoblastic leukemia

A role for specific human leukocyte antigen (HLA) variants in the etiology of childhood acute lymphoblastic leukemia (ALL) has been extensively studied over the last 30 years, but no unambiguous association has been identified. To comprehensively study the relationship between genetic variation within the 4.5 Mb major histocompatibility complex genomic region and precursor B-cell (BCP) ALL risk, we analyzed 1075 observed and 8176 imputed single nucleotide polymorphisms and their related haplotypes in 824 BCP-ALL cases and 4737 controls. Using these genotypes we also imputed both common and rare alleles at class I (HLA-A, HLA-B, and HLA-C) and class II (HLA-DRB1, HLA-DQA1, and HLA-DQB1) HLA loci. Overall, we found no statistically significant association between variants and BCP-ALL risk. We conclude that major histocompatibility complex-defined variation in immune-mediated response is unlikely to be a major risk factor for BCP-ALL.