Genetic Characteristics of Non B Cell-Derived Immunoglobulin Genes.

It is widely acknowledged that immunoglobulins (Igs) are produced solely by B-lineage cells. The Ig gene is created by the rearrangement of a group of gene segments [variable (V), diversity (D), and joining (J) segments rearrangement, or V(D)J recombination], which results in the vast diversity of B cell-derived Ig responsible for recognising various antigens. Ig subsequently undergoes somatic hypermutation (SHM) and class switch recombination (CSR) after exposure to antigens, thus converting the low-affinity IgM to IgG, IgA, or IgE antibodies. IgM and IgD are primarily expressed in naïve B cells that have not been exposed to antigens, they do not undergo somatic hypermutation; hence, their variable region sequences remain the same as those in the germline. In contrast, IgG, IgA, and IgE are expressed in antigen-stimulated memory B cells or plasma cells, and thus, they often possess high-frequency mutations in their variable region sequences. Since the discovery that Ig can be produced by non-B cells, Qiu's group has investigated and compared the genetic characteristics of B cell-derived Ig and non-B cell-derived Ig. These findings demonstrated that non-B cell-derived Ig shares certain similarities with B cell-derived Ig in that the sequence of its constant region is identical to that of B cell-derived Ig, and its variable region is also strictly dependent on the rearrangement of V, D, and J gene segments. Moreover, akin to B cell-derived Ig, the V regions of IgM and IgD are rarely mutated, while IgG, IgA, and IgE produced by cancer cells are frequently mutated. However, the non-B cell-derived Ig V region sequence displays unique characteristics. (1) Unlike the vast diversity of B cell-derived Igs, non-B cell-derived Igs exhibit restricted diversity; cells from the same lineage always select the same V(D)J recombination patterns; (2) Both mRNA and proteins of RAG1/RAG2 recombinase have been detected in Ig positive cancer cell lines and normal tissues. But Ig recombination could also be found in RAG1-/- and RAG2-/- mice, suggesting that they are not necessary for the rearrangement of non-B cell-derived Igs. These features of non-B cell-derived Igs suggest a potentially undiscovered mechanism of V(D)J recombination, ligation, and SHM in non-B cells, which necessitates further investigation with advanced technology in molecular biology.

Differential analysis of immunoglobulin gene expression pattern in chickens of distinct breeds and developmental periods.

Immunoglobulin is an essential component of the body's defense against pathogens, aiding in the recognition and clearance of foreign antigens. Research concerning immunoglobulin gene and its diversity of expression across different breeds within the same species is relatively scarce. In this study, we employed RACE (Rapid Amplification of cDNA Ends) technology, prepared DNA libraries, performed high-throughput sequencing, and conducted related bioinformatics analysis to analyze the differences in immunoglobulin gene diversity and expression at different periods in Hy-line brown hens, Lueyang black-bone chickens, and Beijing-You chickens. The study found that the composition of chicken immunoglobulin genes is relatively simple, with both the light chain and heavy chain having a functional V gene. Additionally, the mechanisms of immunoglobulin diversity generation tended to be consistent among different breeds and periods of chickens, primarily relying on abundant junctional diversity, somatic hypermutation (SHM), and gene conversion (GCV) to compensate for the limitations of low-level V(D)J recombination. As the age increased, the junctional diversity of IgH and IgL tended to diversify and showed similar expression patterns among different breeds. In the three chicken breeds, the predominant types of mutations observed in IGHV and IGLV SHM were A to G and G to A transitions. Specifically, IGLV exhibited a preference for A to G mutations, whereas IGHV displayed a bias toward G to A mutations. The regions at the junctions between framework regions (FR) and complementarity-determining regions (CDR) and within the CDR regions themselves are typically prone to mutations. The locations of GCV events in IGLV and IGHV do not show significant differences, and replacement segments are concentrated in the central regions of FR1, CDR, and FR2. Importantly, gene conversion events are not random occurrences. Additionally, our investigation revealed that CDRH3 in chickens of diverse breeds and periods the potential for diversification through the incorporation of cysteine. This study demonstrates that the diversity of immunoglobulin expression tends to converge among Hy-line brown hens, Lueyang black-bone chickens, and Beijing-You chickens, indicating that the immunoglobulin gene expression mechanisms in different breeds of chickens do not exhibit significant differences due to selective breeding.

Immunoglobulins play a key role in the organism's defense against pathogens, and their diverse expression allows the body to generate a wide array of antibodies. This diversity serves as a critical safeguard for the immune system against various pathogens. Natural geographical variances and artificial breeding and selection can potentially lead to different immune responses in distinct populations of the same species when confronted with the same pathogen. In this study, we investigated the diversity of immunoglobulin gene expression in the natural state of different chicken breeds (Hy-line brown hens, Lueyang black-bone chickens, and Beijing-You chickens) and at different periods from the perspective of immunoglobulin gene expression mechanism. We analyzed the diversity of immunoglobulin based on the results of high-throughput sequencing by extracting Fabricius bursa RNA, RACE (Rapid Amplification of cDNA Ends) technique, and constructing DNA libraries. Our study reveals that the junctional diversity, somatic hypermutation, CDR3 diversity, and gene conversion expression of immunoglobulins in Hy-line brown hens, Lueyang black-bone chickens, and Beijing-You chickens converge during the same time period. This indicates that the immunoglobulin gene expression mechanisms in different chicken breeds do not exhibit significant variations as a result of selective breeding.

Primary Immunodeficiency in South China: Clinical Features and a Genetic Subanalysis of 138 Children

Objetivos: El objetivo de este estudio fue analizar los datos clínicos en 138 casos de pacientes con inmunodeficiencia primaria (IDP) y realizar el diagnóstico genético con el fin de mejorar la capacidad de su diagnóstico para pediatras, especialmente en el sur de China. Métodos: Se realizó un análisis retrospectivo de pacientes con IDP hospitalizados entre mayo de 1999 y junio del 2012, realizando el estudio genético en 59 casos. Resultados: En cuanto a los resultados obtenidos comprobamos como las manifestaciones clínicas más frecuentes fueron fiebre e infecciones de repetición, generalmente respiratorias y digestivas. En 138 pacientes estudiados la relación varón: mujer fue 113:25, la edad de comienzo 0-119 meses, la edad de diagnóstico 2-159 meses. En 20 casos (14.49%) había una historia familiar de infecciones recurrentes o de miembros muertos en la infancia por dichas infecciones. En 48 casos (34.78%) se evidenciaron defectos en la producción de anticuerpos, 45 casos (32.61%) mostraban inmunodeficiencia común combinada, y 45 casos (32.61%) otros síndromes de inmunodeficiencias bien definidas. En 59 casos se realizó estudio genético encontrando en 24 de ellos (15.94%) una clara mutación genética, incluyendo 8 casos con Hipogammaglobulinemia selectiva con déficit de IgA, 8 casos con inmunodeficiencia combinada de células T y B, 3 casos de inmunodeficiencia combinada con aumento de IgM, 3 casos con aumento de IgE, 2 casos con CGD. Se encontraron 4 mutaciones nuevas. El resto de los 35 casos no mostraron mutaciones relevantes. Tras el tratamiento con inmunoglobulinas intravenosas y antibióticos, 16 pacientes fallecieron en el hospital, otros 5 tras el tratamiento, siendo la mortalidad del 15.22%. Conclusiones: En conclusión, en los últimos años se aprecia una elevación de la incidencia de pacientes con IDP en el sur de China. El análisis genético confirma el diagnóstico de la enfermedad, que afecta gravemente la calidad de vida de los niños, siendo muy importante su diagnóstico y tratamiento precoz. Los resultados de este estudio pueden guiar el protocolo de estudio de la IDP (AU)

Objectives: We analyzed the clinical features of 138 patients with primary immunodeficiency (PID) and performed genetic testing on a subset of patients in order to complete gaps in research on PID in South China and thus improve pediatricians' ability to recognize and diagnose PID. Methods: We performed a retrospective analysis based on the medical records of PID patients hospitalized in our institution between May 1999 and June 2012. Gene sequencing was performed in 59 cases. Results: Children with PID usually present with fever and repeated infections that generally affect the respiratory and digestive tracts. Growth retardation is observed in some cases. Of the 138 patients, 113 were boys, median age at onset was 5 months (range, 0-119 months), and age at diagnosis was 10 months (2-159 months). A family history of repeated infection or death of family members in infancy because of recurrent infections was recorded in 20 cases (14.49%). Antibody defects were detected in 48 cases (34.78%), combined immunodeficiency disease in 45 cases (32.61%), and other well-defined immunodeficiency syndromes in 45 cases (32.61%). Of the 59 patients from the genetic subanalysis, 24 (15.94%) had a genetic mutation (x-linked agammaglobulinemia, 8 cases; severe combined immunodeficiency, 8 cases; hyperimmunoglobulin M syndrome, 3 cases; hyperimmunoglobulin E syndrome, 3 cases; chronic granulomatous disease, 2 cases). We detected 4 novel mutations. No relevant mutations were found in the remaining 35 cases. After treatment with intravenous immunoglobulin and anti-infectious agents, 16 patients died in hospital, and 5 cases died after discontinuing treatment (mortality, 15.22%). Conclusions: In recent years, the number of patients with PID has risen gradually in South China. Genetic testing can confirm diagnosis (AU)