A preliminary gene expression profile of acute graft-versus-host disease.

Allogeneic hematopoietic stem cell transplantation (HSCT) is the treatment of choice for high-risk hematological malignancies, yet a major complication associated with this therapy is acute graft-versus-host disease (GVHD). Despite a well-defined pathophysiological mechanism, there are no definitive markers for predicting acute GVHD development or progression to advanced stages. In the current study, we enrolled four acute GVHD and four acute GVHD-free recipients of allogeneic HSCT and collected peripheral blood just prior to onset of clinical acute GVHD for analysis on Affymetrix GeneChip Human Genome U133 Plus 2.0 microarrays. We noted significant differences in expression of 1,658 genes between control and acute GVHD patients, based on an analysis of covariance (ANCOVA) by type of transplant, a pooled error estimate, and a false discovery rate (FDR) of 10%. In conclusion, we offer the first report of a preliminary molecular signature of acute GVHD in allogeneic HSCT patients.

Hematopoietic stem cell mobilization with G-CSF induces innate inflammation yet suppresses adaptive immune gene expression as revealed by microarray analysis.

OBJECTIVE: Granulocyte colony-stimulating factor (G-CSF) is used to boost granulocyte counts in immunocompromised patients, but its effects on the immune system may be counterproductive. We tested the hypothesis that G-CSF-mobilized peripheral blood stem cell (PBSC) products are immunologically downregulated based on gene microarray analysis. METHODS: Ten peripheral blood samples from normal donors for allogeneic PBSC transplantation were obtained before and after administration of G-CSF and tested on Affymetrix Human U133 Plus 2.0 GeneChip microarrays and by flow cytometry. Significant changes in gene expression after G-CSF were reported by controlling the false discovery rate at 5%. The quantitative real-time polymerase chain reaction method was used to validate expression of representative genes. RESULTS: All immune cells measured, including neutrophils, monocytes, lymphocytes, and dendritic cells, were significantly increased after G-CSF. In terms of gene expression, inflammatory and neutrophil activation pathways were upregulated after G-CSF. However, adaptive immune-related gene expression, such as antigen presentation, co-stimulation, T-cell activation and cytolytic effector responses, were downregulated. CONCLUSION: Despite significant increases in lymphocytes and antigen-presenting cells, G-CSF-mobilized PBSC allografts exhibit a suppressive adaptive immune-related gene-expression profile. However, innate and inflammatory responses are elevated. Our data provides an explanation for the potentially immunosuppressive effects observed after G-CSF administration.

Resolution of the novel immune-type receptor gene cluster in zebrafish.

The novel immune-type receptor (NITR) genes encode a unique multigene family of leukocyte regulatory receptors, which possess an extracellular Ig variable (V) domain and may function in innate immunity. Artificial chromosomes that encode zebrafish NITRs have been assembled into a contig spanning approximately 350 kb. Resolution of the complete NITR gene cluster has led to the identification of eight previously undescribed families of NITRs and has revealed the presence of C-type lectins within the locus. A maximum haplotype of 36 NITR genes (138 gene sequences in total) can be grouped into 12 distinct families, including inhibitory and activating receptors. An extreme level of interindividual heterozygosity is reflected in allelic polymorphisms, haplotype variation, and family-specific isoform complexity. In addition, the exceptional diversity of NITR sequences among species suggests divergent evolution of this multigene family with a birth-and-death process of member genes. High-confidence modeling of Nitr V-domain structures reveals a significant shift in the spatial orientation of the Ig fold, in the region of highest interfamily variation, compared with Ig V domains. These studies resolve a complete immune gene cluster in zebrafish and indicate that the NITRs represent the most complex family of activating/inhibitory surface receptors thus far described.