Dendritic cell lineage, plasticity and cross-regulation.

Dendritic cells (DCs) are professional antigen-presenting cells that have an extraordinary capacity to stimulate naïve T cells and initiate primary immune responses. Here we review progress in understanding the additional functions of DCs in regulating the types of T cell-mediated immune responses and innate immunity to microbes. In addition, evidence for the existence of myeloid and lymphoid DC lineages and their different functions are summarized. We propose that the diverse functions of DCs in immune regulation are dictated by the instructions they received during innate immune responses to different pathogens and from their evolutionary lineage heritage.

Thyroglobulin type-I-like domains in invariant chain fusion proteins mediate resistance to cathepsin L digestion.

The MHCII associated invariant chain isoform Ii41 shows homology to a repeat in thyroglobulin (TgR). We show that the Ii31 isoform, which lacks the TgR-like domain, is sensitive to cathepsin L treatment whereas Ii41 displays substantial resistance. The TgR-like sequence of Ii41 was exchanged for thyroglobulin type-IA and -IB repeats, that contain six or four cysteine residues. Resistance to cathepsin L digestion was maintained upon substitution of the Ii41 TgR for homologous sequences from TgR type-IA. Mutation of a conserved cysteine in the TgR domain of an Ii fusion protein strongly reduced resistance to cathepsin L digestion.

Hodgkin and Reed-Sternberg-like cells in B-cell chronic lymphocytic leukemia represent the outgrowth of single germinal-center B-cell-derived clones: potential precursors of Hodgkin and Reed-Sternberg cells in Hodgkin's disease.

In rare cases of B-cell chronic lymphocytic leukemia (B-CLL), large cells morphologically similar to or indistinguishable from Hodgkin/Reed-Sternberg (HRS) cells of Hodgkin's disease (HD) can be found in a background of otherwise typical B-CLL. To test these HRS-like cells for a potential clonal relationship to the B-CLL cells, single cells were micromanipulated from immunostained tissue sections, and rearranged immunoglobulin genes were amplified from HRS-like cells and B-CLL cells and sequenced. The same variable (V) gene rearrangements with shared and distinct somatic mutations were found in HRS-like and B-CLL cells from 1 patient, which indicates derivation of these cells from 2 distinct members of a germinal-center B-cell clone. Separate clonal V gene rearrangements were amplified from HRS-like and B-CLL cells from 2 other patients, showing concomitant presence of 2 distinct expanded B-cell clones. Epstein-Barr virus (EBV) was detected in the HRS-like cells of these 2 latter cases, indicating clonal expansion of an EBV-harboring B cell in the setting of B-CLL. There is evidence that HRS-like cells in B-CLL, like HRS cells in HD, derive from germinal-center B cells. In all cases, somatic mutations have been detected in the rearranged V genes of the HRS-like cells, and in 1 of the EBV-positive HRS-like cell clones, somatic mutations rendered an originally functional V gene rearrangement nonfunctional. We speculate that the HRS-like cells in B-CLL represent potential precursors for HRS cells causing HD.

Somatic mutations within the untranslated regions of rearranged Ig genes in a case of classical Hodgkin's disease as a potential cause for the absence of Ig in the lymphoma cells.

Hodgkin-Reed-Sternberg (H-RS) cells are clonal B cells carrying Ig gene rearrangements. However, in situ hybridization methods failed to demonstrate Ig gene expression in H-RS cells of classical Hodgkin's disease (HD). Because somatic mutations rendering potentially functional Ig gene rearrangements nonfunctional were detected in some cases of the disease, it was speculated that H-RS cells in classical HD may have lost the ability to express antigen receptor as a rule. Recently, we established a novel cell line (L1236) from H-RS cells of a patient with mixed cellularity subtype of HD. L1236 cells harbor a potentially functional VH1 and a potentially functional Vkappa3 gene rearrangement. However, no antibody expression was detected. To show potential reasons for this lack of Ig expression, we analyzed the genomic organization of the Ig genes and their transcription in the primary and cultivated H-RS cells of this patient. The H-RS cells were found to have switched their isotype to IgG4, confirming their mature B-cell nature. By amplifying cDNA from L1236 cells as well as from frozen biopsy material transcripts of the Vkappa3 and the VH1 gene rearrangement were detected for both sources of cDNA. However, Northern blot hybridization of L1236 RNA failed to demonstrate VH1 and Vkappa3 transcripts, indicating only a low level of transcription. Sequence analysis of the promoter and leader regions of the VH1 gene rearrangement from L1236 cells as well as from lymphoma-affected tissue showed a somatic mutation in the conserved octamer motif of the promoter region. Somatic mutations were also detected within the 3' splice site of the leader intron and adjacent nucleotides in the rearranged Vkappa light chain gene, leading to aberrant splicing. These mutations might prevent the generation of adequate amounts of functional Ig gene transcripts as template for translation into protein. Thus, mutations in H-RS cells that prevent Ig gene expression might also be located outside the coding region of the Ig genes.

Detection of clonal Hodgkin and Reed-Sternberg cells with identical somatically mutated and rearranged VH genes in different biopsies in relapsed Hodgkin's disease.

Hodgkin's disease (HD) represents a malignant lymphoma in which the putative malignant Hodgkin and Reed-Sternberg (H-RS) cells are rare and surrounded by abundant reactive cells. Single-cell analyses showed that H-RS cells regularly bear clonal Ig gene rearrangements. However, there is little information on the clinical evolution of HD in a given patient. In this study, we used the single-cell polymerase chain reaction (PCR) to identify H-RS cells with clonal Ig gene rearrangements in biopsy specimens of patients with relapsed HD. The obtained clonal variable region heavy-chain (VH) gene rearrangements were used to construct tumor-clone-specific oligonucleotides spanning the complementarity determining region (CDR) III and somatically mutated areas in the rearranged VH gene. A number of biopsies were obtained during a period of 3 years from two HD patients. H-RS cells with identical VH rearrangements were detected in two separate infiltrated lymph nodes from one patient with nodular sclerosis HD. In a second patient with mixed cellularity HD subtype, clonal VH rearrangements with identical sequences were detected in infiltrated spleen and two lymph node biopsies. Despite the high sensitivity of the PCR method used (one clonal cell in 10(5) mononuclear cells), residual H-RS cells were not found in peripheral blood, leukapheresis material, purified CD34(+) stem cells or bone marrow. The results show that different specimens from relapsed patients suffering from classical HD carry the same clonotypic IgH rearrangements with identical somatic mutations, demonstrating the persistence and the dissemination of a clonal tumor cell population. Thus, PCR assays with CDRIII-specific probes derived from clonal H-RS cells are of clinical importance in monitoring the dissemination of HD and tumor progression and could be useful for analysis of minimal residual disease after autologous stem cell transplantation.

Somatic hypermutation in normal and transformed human B cells.

In the human, most IgM+IgD+ as well as CD5+ peripheral blood B cells express unmutated V genes and thus can be assigned to a pre-germinal centre (GC) stage of development. The memory B-cell compartment generated in the GC reaction and characterized by cells bearing somatically mutated V-region genes consists not only of class-switched cells, but also of IgM-only B cells and perhaps a subset of IgM+IgD+B cells expressing the CD27 antigen. Comparison of the rearranged V-region genes of human B-cell lymphomas with those of the normal B-cell subsets allows the identification of the progenitor cells of these tumours in terms of their stage of maturation. On this basis, most B-cell non-Hodgkin lymphomas, and in addition Hodgkin and Reed-Sternberg (HRS) cells in Hodgkin's disease (HD), are derived from B cells at a GC or post-GC stage of development. The mutation pattern indicates that the precursors of the tumour clones have been stringently selected for expression of a functional antigen receptor with one notable exception: HRS cells in classical (but not lymphocyte-predominant) HD appear to be derived from "crippled" GC B cells. Sequence analysis of rearranged V genes amplified from single tonsillar GC B cells revealed that the somatic hypermutation process introduces deletions and/or insertions into V-region genes more frequently than indicated by previous investigations. Presumably, this feature of the hypermutation mechanism is often responsible for the generation of heavy chain disease, and also several types of chromosomal translocations of oncogenes into immunoglobulin loci in human B-cell lymphomas.

Detection of identical Hodgkin-Reed Sternberg cell specific immunoglobulin gene rearrangements in a patient with Hodgkin's disease of mixed cellularity subtype at primary diagnosis and in relapse two and a half years later.

BACKGROUND: The malignant nature of Hodgkin-Reed Sternberg (H-RS) cells has been questioned due to their scarcity in lymphoma tissues. Recently, using micromanipulation of H-RS cells and single cell PCR evidence was obtained that H-RS cells represent a clonal B-cell population. In these studies H-RS cells were isolated from each one lymph node for a given case. In classical Hodgkin's disease (HD) it thus could not be ruled out that H-RS cell clonality reflected a locally restricted clonal proliferation. We analysed biopsy specimens from a patient suffering from HD for the presence of clonally related H-RS cells at primary diagnosis and during relapse of the disease. MATERIALS AND METHODS: In 1994 the H-RS cell line L1236 was generated from the peripheral blood of a patient suffering from a disseminating relapse of HD of mixed cellularity subtype. The patient had relapsed despite intensive treatment including high dose chemotherapy and autologous bone marrow transplantation. The clonal identity of this cell line with H-RS cells in situ was proven by amplifying identical Ig gene rearrangements of the cell line as well as of single H-RS cells picked from the patients bone marrow. Primers covering the CDR3 region were chosen from the H-RS cell specific VH1 gene rearrangement to detect H-RS cells of the identical clone by amplifying the rearranged VH1 genes in tissue samples obtained during disseminating relapsing disease and at primary diagnosis of HD in 1991. RESULTS: The H-RS cell specific DNA sequence was detected in all affected tissues analysed including the cervical lymph node which has been exstirpated at primary diagnosis. CONCLUSION: This finding indicates the existence of a clonal H-RS cell population during the first manifestation of HD and persistence and dissemination of this clone despite aggressive treatment. Thus, in the described case the malignant nature of H-RS cells defined by dissemination and recurrence of the identical H-RS cell clone in relapsing disease is proven.

Normal and malignant B-cell development with special reference to Hodgkin's disease.

During their development, B lymphocytes are repeatedly selected for the expression of an appropriate surface receptor: the pre-B-cell receptor at the pre-B-cell stage and surface immunoglobulin (Ig) at the transition from a pre-B cell to a mature B cell. Furthermore, stringent selection for B cells expressing high affinity antibodies operates when antigen-activated B cells proliferate within germinal centers (GC). Here, somatic point mutations are introduced into rearranged V region genes at a high rate, and B cells acquiring favorable mutations are selected to differentiate into memory B cells or plasma cells. In the frame of this developmental scheme, extending a recent analysis, we investigated 10 primary cases of Hodgkin's disease (HD) for B-lineage origin and clonality [1]. Single Hodgkin and Reed-Sternberg (H-RS) cells were micromanipulated from frozen tissue sections and analyzed by PCR for rearranged V genes. Clonal VH and/or V kappa/ V delta gene rearrangements were obtained from 9 of the cases. This shows that H-RS cells represent a clonal, B-lineage-derived population of tumor cells. Somatic mutations were found in all clonal VH gene rearrangements. Interestingly, mutations leading to stop codons in in-frame V gene rearrangements were detected in four cases. Since GC B cells acquiring such crippling mutations are usually efficiently eliminated within the GC, the finding of those mutations indicates that H-RS cells are derived from precursors within the GC that escaped apoptosis by a transforming event.

Molecular single cell studies of normal and transformed lymphocytes.

The polymerase chain reaction allows the characterization of RNA and DNA sequences from single cells. Methods were established to analyse single cells isolated from suspension or by multicolour flow cytometry. We established a method to isolate single immunostained cells from frozen tissue sections and to analyse those cells for immunoglobulin gene rearrangements. This method was first used to study B cell differentiation within human germinal centres. In another series of experiments, Hodgkin and Reed-Sternberg (HRS) cells from a total of 14 cases of HD were analysed for B lineage derivation and clonality. In 13 of the 14 cases, clonal V gene rearrangements were identified. This shows that HRS cells generally represent the outgrowth of a clonal population of B cells. The detection of somatic mutations in all VH gene rearrangements amplified from HRS cells and the nature of those mutations identifies a GC B cell as the HRS precursor.

Hodgkin and Reed-Sternberg cells in Hodgkin's disease represent the outgrowth of a dominant tumor clone derived from (crippled) germinal center B cells.

In Hodgkin's disease (HD), the Hodgkin and Reed-Sternberg (HRS) cells represent only a minute population in the diseased tissue. The investigation of lineage derivation and clonal origin of these cells has yielded conflicting results. We have analyzed HRS cells micromanipulated from infiltrated tissue sections of 10 primary HD patients for rearranged V genes, extending a previous study. Clonally related rearrangements were found in nine cases, indicating that HRS cells represent a dominant clone of B lineage-derived cells in at least a large fraction of cases of HD. Rearranged VH genes from HRS cells carried a high load of somatic mutation, indicating that HRS cells are derived from germinal center (GC) cells or their progeny. Stop codons in some in-frame V gene rearrangements suggest that the HRS cell precursors reside inside GCs, have acquired crippling mutations that prevent antigenic selection, but escape apoptosis through some transforming event.

Molecular single cell analysis demonstrates the derivation of a peripheral blood-derived cell line (L1236) from the Hodgkin/Reed-Sternberg cells of a Hodgkin's lymphoma patient.

A novel cell line, L1236, was established from the peripheral blood of a patient with Hodgkin's disease (HD). Two Ig VH and one Vkappa gene rearrangements were amplified by polymerase chain reaction (PCR) from the DNA of this cell line, demonstrating its derivation from the B-cell lineage. To test the cell line for its clonal relationship to the Hodgkin/Reed-Sternberg (H-RS) cells in the patient, single H-RS cells were micromanipulated from tissue sections of a tumor-infiltrated bone marrow specimen from that patient and analyzed by PCR for Ig gene rearrangements. The same rearrangements detected in the cell line were also found repeatedly in H-RS cells of the biopsy material. Thus, L1236 is the first cell line established from a case of HD for which a derivation from the H-RS cells of the patient could be demonstrated. Furthermore, the selective isolation of identical V gene rearrangements from multiple single H-RS cells demonstrates that these cells represented a clonal population in the patient.

Single cell analysis of Hodgkin/Reed-Sternberg cells.

The origin and clonality of the Hodgkin and Reed-Sternberg (HRS) cells in Hodgkin's disease (HD) has been much debated. Recently, single cell PCR techniques were established, allowing the study of HRS cells at the single cell level. HRS cells were analysed for Ig gene rearrangements to reveal a potential origin from B lineage cells. Whereas one study did not detect any V gene rearrangements, such rearrangements were found in three other investigations. However, whereas our own group detected clonal V gene rearrangements in the HRS cells of 11 (10 classical and one lymphocyte predominant) out of 12 cases of HD and no rearrangements in the twelfth, Delabie et al. (Blood 1994; 84: 3291-8) described four cases of lymphocyte predominant HD with polyclonal V gene rearrangements and Hummel and colleagues detected monoclonal as well as polyclonal and "mixed' populations of HRS cells in cases of classical HD. Potential reasons for the differing results of those investigations are discussed.

Evidence for two distinct azurins in Alcaligenes xylosoxidans (NCIMB 11015): potential electron donors to nitrite reductase.

We have isolated two type 1 copper-containing proteins (M(r) approximately 13K) from Alcaligenes xylosoxidans (NCIMB 11015) grown under denitrifying conditions. Amino acid sequence analysis of these two proteins shows one to be the previously identified azurin (Ambler, 1971), which we shall call azurin I, and the other to be a related, but previously undescribed, blue copper protein which we show to also be an azurin and propose to call azurin II. Thus, NCIMB 11015 becomes the second system where two distinct azurins are found, the other being Methylomonas J (Ambler & Tobari, 1989). On isoelectric focusing, azurin I migrates very similarly to the previously identified azurin from this organism while azurin II migrates similarly to azurin purified from Alcaligenes denitrificans NCTC 8582. The sequence of azurin II is 33% different than the azurin I sequence but is only 11% different than the azurin from Alcaligenes denitrificans NCTC 8582. Optical spectra for the two proteins are very similar with epsilon mM values of 6.27 and 5.73 mM-1 cm-1 for azurin I and II, respectively, at lambda max approximately 620 nm. The 291 nm shoulder normally ascribed to the hydrophobic nature of tryptophan 48 is clearly observed in azurin I but is missing in azurin II. Amino acid analysis confirms that this tryptophan is missing in azurin II. Azurin I and azurin II show essentially the same redox potential of 305 +/- 10 mV at pH 7.5 and are equally effective electron donors to the purified dissimilatory nitrite reductase of Alc. xylosoxidans in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)