Stability and prognostic influence of FLT3 mutations in paired initial and relapsed AML samples.

In acute myeloid leukemia (AML), activating mutations in the fms-like tyrosine kinase 3 (FLT3) gene predict poor prognosis. We determined FLT3 internal tandem duplications (FLT3/ITD) and D835 point mutations in paired initial and relapse samples from 80 pediatric and adult AML patients. One D835 point mutation was found in an initial pediatric AML sample. Fms-like tyrosine kinase 3/ITDs were present in 21 initial and 22 relapse samples (26.3 and 27.5%, respectively). Interestingly, FLT3/ITD positivity was related to a significantly shorter time to relapse, most pronounced when the ITD-positive status was found at relapse (P<0.001). However, FLT3/ITD status changed between diagnosis and relapse in 14 cases. In four patients, the FLT3/ITD became undetectable at relapse in five patients FLT3/ITDs were only detected at relapse, and in five patients the length or number of FLT3/ITDs changed. Gain of FLT3/ITDs may suggest oligoclonality with selective outgrowth of the FLT3/ITD-positive clone, whereas losses may reflect ITDs in the more mature leukemic cells rather than in the leukemic stem cell, or, alternatively, that other genetic aberrations provided a greater selective advantage. Studying FLT3/ITD kinetics in minimal residual disease setting may provide some answers for the changes we observed. Fms-like tyrosine kinase 3/ITD is a relevant marker for prognosis, and remains an important target for therapeutic inhibition.

Proteoglycans on bone marrow endothelial cells bind and present SDF-1 towards hematopoietic progenitor cells.

Recognition events between hematopoietic progenitor cells (HPC) and bone marrow endothelial cells (BMEC) initiate homing of HPC to the bone marrow. The chemokine SDF-1 is present on BMEC and plays a crucial role in bone marrow engraftment. We studied the role of proteoglycans (PGs) on BMEC in binding and presentation of SDF-1. SDF-1 mRNA was present in three human BMEC cell lines. Competition experiments showed that 125I-SDF-1 alpha binding to the BMEC cell line 4LHBMEC was inhibited by heparins, heparan sulfate (HS) intestinal mucosa, chondroitin and dermatan sulfate (CS/DS), but not by HS bovine kidney. Pretreatment of 4LHBMEC with glycosaminoglycan (GAG)-degrading enzymes or sodium chlorate demonstrated that SDF-1 bound to both HSPGs and CS/DSPGs in a sulfation-dependent manner, as determined with an SDF-1 antibody recognizing the CXCR4-binding site. 4LHBMEC bound four-fold more SDF-1 than HUVEC. Isolated endothelial PGs did not bind SDF-1 in a filter or microplate-binding assay, suggesting the necessity of membrane association. In flow adhesion experiments, endothelial arrest of CXCR4+ KG-1 and not of CXCR4- KG-1a cells increased significantly when SDF-1 was presented on 4LHBMEC. In conclusion, SDF-1 is produced by BMEC and binds to the BMEC cell surface via HS and CS/DS-GAGs, thereby presenting its CXCR4 binding site to HPC contributing to their arrest.

Storage of unprocessed G-CSF-mobilized whole blood in a modified Leibovitz's L15 medium preserves clonogenic capacity for at least 7 days.

Autologous stem cell transplantation using unprocessed, G-CSF-mobilized whole blood (WB) is a simple, cost-reducing procedure and supports high-dose chemotherapy regimens not exceeding 72 h. Thereafter, clonogenic capacity rapidly decreases if routine anticoagulants are used for storage. In order to increase clinical applicability, we investigated the requirements for optimal preservation of unprocessed WB for 7 days. During storage at 22 degrees C in CPDA-1, a decrease in pH was noted, which was at least partially responsible for the low recovery of clonogenic cells. Subsequently, WB cells were stored in various cell culture media (RPMI 1640, alpha-MEM, X-VIVO15, CellGro SCGM and Leibovitz's L15 medium) containing either serum, serum-free substitutes or no additives. Leibovitz's L15 showed significantly better CFU-GM recoveries than the other media. Using a calcium-free modification of L15 medium (added 3:10 to WB), 94 +/- 24% of CD34(+) cells, 41 +/- 14% of BFU-E, 56 +/- 17% CFU-GM and 90 +/- 14% of LTC-IC were preserved during storage for 7 days at 22 degrees C. Storage at 4 degrees C was also feasible, but showed less optimal recoveries of 52 +/- 29% (CD34), 32 +/- 10% (BFU-E), 13 +/- 7% (CFU-GM) and 58 +/- 9% (LTC-IC). The expression of CD38, Thy-1, c-kit, AC133, L-selectin and CXCR4 on CD34-positive cells remained unchanged. In conclusion, a modified Leibovitz's L15 medium better meets the metabolic requirements of a high-density cell culture and allows safe storage of G-CSF mobilized WB for at least 7 days. The results encourage further exploration of WB transplants stored for 7 days for clinical use.

A single-step colony-forming unit assay for unseparated mobilized peripheral blood, cord blood, and bone marrow.

The colony-forming unit (CFU) assay is exposed to a lot of variation, part of which is introduced by several enrichment strategies that are routinely performed before assessment of clonogenic capacity in mobilized peripheral blood (PB), bone marrow (BM), or cord blood (CB). We investigated the possibility to perform a single-step CFU assay by direct plating of PB, BM, or CB into CFU culture medium to obtain more reproducible results than after a standard Ficoll or lysis procedure. Direct plating implies the presence of red blood cells (RBC), white blood cells (WBC), and plasma in the CFU assay, which could possibly influence the outcome of the assay. Of all components, only the RBC was found to negatively influence CFU-GM growth if a concentration of > 0.02 x 10(9)/ml was present in the CFU culture medium. Subsequently, depending on the RBC concentration PB, BM, and CB samples were prediluted in triplicate or quadruplicate and plated into CFU medium. Lysis and/or Ficoll procedures were also performed in triplicate or quadruplicate on the same samples, and the mean colony number and coefficient of variation (CV) of the three techniques were compared. Significantly smaller CV values were found using the direct plating technique (all assays, mean 7.5%, range 1.6-15.6%) than after Ficoll separation (mean 18.0%, range 2.2-62.5%). Intermediate results were obtained with the lysis method (mean CV 11.6%, range 3.3-29%). In most samples, and especially in those with a very low number of clonogenic cells per milliliter, more colonies were detected with the direct plating method than with either the lysis or Ficoll method. In conclusion, the single-step direct plating method significantly enhances reproducibility of the CFU assay for PB, BM, and CB samples in comparison with standard techniques by circumvention of loss of colony formation and by decreasing variability. Furthermore, the direct plating technique is a timesaving assay.

Differences in cytokine mRNA profiles between premalignant and malignant lesions of the uterine cervix.

The aim of this study was to assess the expression of cytokine transcripts, reflecting the type of ongoing immune responses at the site of human papillomavirus (HPV) infection, in relation to the development of cervical neoplasia. To this end reverse transcription-polymerase chain reaction (RT-PCR) was performed for interferon (IFN) gamma, interleukin (IL)-2, IL-4, IL-5, IL-10, IL-12 (p35 and p40), and transforming growth factor (TGF beta 1) in snap-frozen cervical biopsies, which were tested for the presence of high risk HPV DNA and histologically classified from normal to invasive carcinoma (n = 40). IFN gamma, IL-10 and IL-12 (p35 and p40) transcripts were found to be expressed at significantly lower frequencies in invasive carcinoma as compared with premalignant biopsies (P = 0.006, P = 0.007 and P = 0.002, respectively). IFN gamma IL-10 mRNA were associated with the presence of the IL-12 p35 and p40 transcripts (P = 0.008 and P < 0.00001, respectively). These results are consistent with a locally reduced cellular (type 1) immunity correlating with HPV-induced invasive cervical carcinoma.

Effects of bryostatin-1 on chronic myeloid leukaemia-derived haematopoietic progenitors.

Bryostatin-1 belongs to the family of macrocyclic lactones isolated from the marine bryozoan Bugula neritina and is a potent activator of protein kinase C (PKC). Bryostatin has been demonstrated to possess both in vivo and in vitro anti-leukaemic potential. In samples derived from chronic myeloid leukaemia (CML) patients, it has been demonstrated that bryostatin-1 induces a macrophage differentiation, suppresses colony growth in vitro and promotes cytokine secretion from accessory cells. We investigated the effect of bryostatin-1 treatment on colony-forming unit-granulocyte macrophage (CFU-GM) capacity in the presence of accessory cells, using mononuclear cells, as well as in the absence of accessory cells using purified CD34-positive cells. Cells were obtained from 14 CML patients as well as from nine controls. Moreover, CD34-positive cells derived from CML samples and controls were analysed for stem cell frequency and ability using the long-term culture initiating cell (LTCIC) assay at limiting dilution. Individual colonies derived from both the CFU-GM and LTCIC assays were analysed for the presence of the bcr-abl gene with fluorescence in situ hybridization (FISH) to evaluate inhibition of malignant colony growth. The results show that at the CFU-GM level bryostatin-1 treatment resulted in only a 1.4-fold higher reduction of CML colony growth as compared to the control samples, both in the presence and in the absence of accessory cells. However, at the LTCIC level a sixfold higher reduction of CML growth was observed as compared to the control samples. Analysis of the LTCICs at limiting dilution indicates that this purging effect is caused by a decrease in output per malignant LTCIC combined with an increase in the normal stem cell frequency. It is concluded that bryostatin-1 selectively inhibits CML growth at the LTCIC level and should be explored as a purging modality in CML.

Differentiation and cell-type-restricted expression of HOXC4, HOXC5 and HOXC6 in myeloid leukemias and normal myeloid cells.

HOX genes have shown a lineage-specific expression in hematopoiesis and are suggested as being involved in the expression of certain adhesion molecules. Recently, we have demonstrated that HOXC4 and HOXC6, but not HOXC5, are expressed during lymphoid differentiation. Reports on the expression of these genes in myeloid leukemias and normal myeloid cells are still scarce. Therefore, we have investigated the expression of HOXC4, HOXC5 and HOXC6 in purified subpopulations of bone marrow in addition to 36 specimens of acute myeloid leukemias (AMLs), eight chronic myeloid leukemias (CMLs), several myeloid cell lines and cutaneous localizations of three myelomonocytic leukemias and one granulocytic sarcoma by RT-PCR and partly by RNA in situ hybridization (RISH). HOXC4 and HOXC6 transcripts were both detected by RT-PCR in 22/36 and 24/36 AMLs, respectively. The distribution of HOXC4 and HOXC6 gene expression over the different types of AML was largely similar and covered all types of AML. In contrast, HOXC5 gene expression was found in only 6/32 AMLs. Expression of HOXC5 was restricted to AMLs of the granulocytic (FAB M1-M3), early monocytic (FAB M4) and early erythroid (FAB M6) lineage. In general, except in one FAB M5b case, no expression of HOXC5 was found in AMLs derived from late stages of monocytic (FAB M5) and megakaryocytic (FAB M7) lineages. As for HOXC4 and HOXC6, expression of HOXC5 was absent in CMLs. Using RISH significant HOXC4, HOXC5 and HOXC6 expression was found in a number of additionally studied AML samples of different FAB classification (M2, M4, M5b and M5b), (M2 and M5b) (M2, M4, M5b), respectively. In tissue localizations of leukemias a different expression pattern of HOXC4, HOXC5 and HOXC6 was found. In contrast to mature leukemic stages of myeloid differentiation, these skin localizations of leukemias expressed HOXC5 and HOXC6. HOXC4 expression was found both in leukemic cells derived from peripheral blood and from cutaneous localizations. Besides HOXC4 expression in monocytes no expression of HOXC4, HOXC5 and HOXC6 was found in granulocytes and monocytes, colonies of growth factor-induced CD34+ bone marrow cells. In earliest CD34+/CD38low and high cell fractions of bone marrow only HOXC4 and in megakaryocytic cells both HOXC4 and HOXC6 were found. Thus, the expression patterns of these HOXC genes found in the limited number of cell fractions of normal bone marrow suggest that the expression patterns found in AMLs and CMLs might reflect the normal situation. Furthermore, the presence of HOXC5 and HOXC6 expression specifically in skin infiltrates of late differentiation stages of myeloid leukemias, suggests an additional role for these genes in the positioning of these myeloid cells in skin tissue.

Differentiation between actinic reticuloid and cutaneous T cell lymphoma by T cell receptor gamma gene rearrangement analysis and immunophenotyping.

AIMS: Differentiation between actinic reticuloid and cutaneous T cell lymphoma can be extremely difficult. Demonstration of clonal T cell receptor (TCR) gene rearrangements has been suggested as a potential diagnostic criterion, but the results obtained thus far have been conflicting. This study investigated whether TCR gamma gene rearrangement analysis, using polymerase chain reaction (PCR) in combination with denaturing gradient gel electrophoresis (DGGE) and immunohistochemistry, can serve as a diagnostic criterion. METHODS: PCR/DGGE was performed on skin, peripheral blood mononuclear cells, and/or lymph nodes of seven patients with actinic reticuloid, 11 patients with Sézary syndrome, and 15 patients with a benign form of erythroderma. The results of PCR/DGGE and Southern blot analysis of TCR beta gene rearrangements were compared. In addition, CD4:CD8 ratios in skin and peripheral blood samples were investigated. RESULTS: Clonal T cell populations were detected in 19 of 21 samples obtained from patients with Sézary syndrome but were not detected in any of the 12 samples from patients with actinic reticuloid. Clonal T cells were detected in the peripheral blood of only one of 15 patients with a benign form of erythroderma. PCR/DGGE and Southern blot analysis gave concordant results in 28 of 29 samples. Immunophenotypic analysis demonstrated increased proportions of CD8+ T cells in skin (seven of seven cases) and peripheral blood (four of seven cases) of patients with actinic reticuloid. CONCLUSION: The results of this study demonstrate that gene rearrangement analysis, in combination with immunohistochemistry, may be an important adjunct in differentiating between actinic reticuloid and cutaneous T cell lymphoma. In patients suspected of having actinic reticuloid, application of both techniques is recommended.

Mobilization of hematopoietic progenitors in patients with chronic myeloid leukemia.

Although the mobilization and harvesting of Philadelphia chromosome-negative progenitors has been proven feasible by a number of groups, it is not clear which techniques should be used with regard to the monitoring of purging and evaluation of stem cell yield. Therefore, we isolated CD34-positive cells from leukapheresis samples of seven CML patients after induction therapy. These cells were analyzed using the colony-forming unit granulocyte-macrophage (CFU-GM) and long-term culture-initiating cell (LTCIC) assays. In addition, we analyzed frequency and clonogenicity of single stem cells using the LTCIC assay at limiting dilution. Individual colonies derived from these assays were subsequently analyzed for the presence of the bcr-abl gene with interphase fluorescence in situ hybridization (FISH) and for the presence of bcr-abl mRNA with RT-PCR. We compared these results with the cytogenetic analysis of the leukapheresis material. Molecular analysis of individual colonies correlated well with the results of cytogenetic analysis. However, in nine out of 18 samples, cytogenetic analysis exclusively demonstrated the presence of either Philadelphia chromosome-positive or -negative cells whereas with the molecular analysis of individual colonies tumor contamination or the presence of residual normal cells could be substantiated. We concluded that molecular analysis of individual colonies should be employed to further optimize induction protocols. With regard to stem cell mobilization we demonstrated that about 67 CFU-GM colonies and clusters were generated by one single LTCIC both for the CML samples and the samples obtained from patients with non-hematologic malignancy. This number is important since until now most centres use a number of four colonies and clusters generated by one LTCIC. Dividing the CFU-GM output in the LTCIC assay by four to determine LTCIC frequency could thus lead to an almost 20-fold overestimation of the LTCIC frequency. It is concluded that stem cell frequency analysis is an important tool with regard to the interpretation of mobilization protocols.

HOXC4, HOXC5, and HOXC6 expression in primary cutaneous lymphoid lesions. High expression of HOXC5 in anaplastic large-cell lymphomas.

Homeobox (HOX) genes are involved in the lineage-specific differentiation of bone marrow stem cells. Recently, we reported a largely similar expression pattern of HOXC4 and HOXC6 in normal and neoplastic cells of the lymphoid lineage. In contrast, HOXC5 was specifically expressed in a subset of B-cell non-Hodgkin's lymphomas (B-NHL) but not in normal lymphocytes or lymphoid leukemias. This might suggest a role for HOXC5 in the pathogenesis of these lymphomas. In the present study the expression of HOXC4, HOXC5, and HOXC6 in primary cutaneous lymphomas was investigated. Using RNA in situ hybridization (RISH) and semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR), we found strong expression of HOXC4 and HOXC6 in all, except one, primary cutaneous lymphomas and all reactive cutaneous lymphoid infiltrates. Interestingly, a strong expression of HOXC5 in primary anaplastic CD30+ large T-cell lymphomas was found. RISH was consistently negative for HOXC5 in all other types of primary cutaneous B- and T-cell lymphomas. However, by semiquantitative RT-PCR these lymphomas showed a weak expression of HOXC5 mRNA. Therefore, we concluded that these lymphomas express low constitutive levels of HOXC5 mRNA. Furthermore, HOXC5 expression was consistently absent in reactive cutaneous lymphoid infiltrates, hyperplastic tonsils and lymph nodes, and peripheral blood lymphocytes either unstimulated or stimulated by a cocktail of CD3 and CD28 antibodies. As a strong expression of HOXC5 in primary cutaneous lymphomas was observed only in anaplastic large T-cell lymphomas and reactive control tissues lacked HOXC5 expression, these data strongly support a role for HOXC5 in the genesis of anaplastic large-T-cell lymphomas.

HOXC4, HOXC5, and HOXC6 expression in non-Hodgkin's lymphoma: preferential expression of the HOXC5 gene in primary cutaneous anaplastic T-cell and oro-gastrointestinal tract mucosa-associated B-cell lymphomas.

Most of the 39 members of the homeobox (HOX) gene family are believed to control blood cell development. HOXC4 and HOXC6 gene expression levels increase with differentiation of lymphoid cells. In contrast, HOXC5 is not expressed in the lymphoid lineage, but was found in lymphoid cell lines, representing the neoplastic equivalents of various differentiation stages of T and B lymphocytes. In the present study, we investigated the HOXC4, HOXC5, and HOXC6 gene expression pattern in 89 non-Hodgkin's lymphomas (NHLs) of different histologic subtypes and originating from different sites. Using RNA in situ hybridization and semiquantitative reverse transcription-polymerase chain reaction, we found expression of HOXC4 in 83 of 88 and HOXC6 in 77 of 88 NHLs and leukemias investigated. In contrast, HOXC5 expression was found in only 26 of 87 NHLs and appeared to be preferentially expressed by two specific subsets of lymphomas, ie, primary cutaneous anaplastic T-cell lymphomas (9 of 9) and extranodal marginal zone B-cell lymphomas (maltomas; 7 of 9). These results indicate that, in contrast to HOXC4 and HOXC6, HOXC5 shows a type- and site-restricted expression pattern in both T- and B-cell NHLs.

Hypersensitivity of bcr-abl-positive progenitors to hyperthermia in patients with chronic myeloid leukemia.

In this study, we evaluated the effect of hyperthermia on hematopoietic progenitors from six chronic myeloid leukemia (CML) bone marrow (BM) samples at diagnosis and four peripheral blood stem cell (PBSC) samples from CML patients after stem cell mobilisation. CD34-positive cells, isolated from these samples, were incubated for 2 h at 37, 42 or 43 degrees C and were plated in the colony-forming unit granulocyte-macrophage (CFU-GM) and the long-term culture initiating cell (LTCIC) assay. To evaluate purging, individual colonies from these assays were analyzed for the presence of the bcr-abl gene with interphase fluorescence in situ hybridization (FISH) and/or RT-PCR. BM samples showed a significant higher sensitivity both at the CFU-GM and LTCIC level, after treatment at 42 degrees C, as compared to the control BM samples obtained from healthy volunteers. The four BM samples of CML patients with a low leukocyte number at diagnosis harbored a mixture of bcr-abl-negative and positive colonies and an increase in the percentage of bcr-abl-negative colonies was observed in all cases. CML patients with a high leukocyte count at diagnosis, however, showed only bcr-abl-positive progenitors even after hyperthermia. PBSCs showed a significant higher sensitivity at the LTCIC level but not at the CFU-GM level, after treatment at 42 degrees C, as compared to the control PBSC samples obtained from nonhematologic cancer patients. Molecular analysis of individual colonies demonstrated an increase of bcr-abl-negative progenitors after thermic treatment in two out of three samples. When comparing both stem cell sources, PBSCs showed a decreased thermic sensitivity as compared to the BM samples at the CFU-GM level, whereas at the LTCIC level an increased thermic sensitivity was observed, both for the controls and the CML samples. In conclusion, both for BM and PBSCs samples, CML progenitors are more sensitive to hyperthermia than control cells, especially at the LTCIC level. In agreement with these results, an increase of bcr-abl-negative progenitors in six out of seven samples could be demonstrated either at the CFU-GM level, LTCIC level or both. Hyperthermia should be explored further as a possible purging modality in CML.

Immunophenotyping and gene rearrangement analysis provide additional criteria to differentiate between cutaneous T-cell lymphomas and pseudo-T-cell lymphomas.

Differentiation between cutaneous pseudo-T-cell lymphomas and cutaneous T-cell lymphomas (CTCLs) may be extremely difficult. In this study, it was investigated whether demonstration of an aberrant phenotype and detection of clonal T-cell receptor gamma (TCR gamma) gene rearrangements can be used as additional differential diagnostic criteria. Immunohistochemical studies and TCR gamma gene rearrangement analysis using a polymerase chain reaction with primers specific for V gamma 1-8 and V gamma 9 gene segments in combination with denaturing gradient gel electrophoresis (PCR/ DGGE) were performed on frozen material of 11 pseudo-T-cell lymphomas and 17 CTCLs, including 9 cases of mycosis fungoides (MF) and 8 pleomorphic CTCLs. Clonal TCR gamma gene rearrangements were found in 66% of patch/plaque-stage MF and 100% of tumor-stage MF and pleomorphic CTCL, but not in any of 10 pseudo-T-cell lymphomas studied. Aberrant expression of CD2, CD3, and/or CD5 antigens was noted in 3 of 6 (50%) cases of patch/plaque-stage MF, all three cases of tumor-stage MF, and 5 of 8 (62%) pleomorphic CTCLs, but not in any of the 11 pseudo-T-cell lymphomas. Moreover, in pseudo-T-cell lymphomas exhibiting a nodular or diffuse growth pattern, a considerable admixture with reactive CD8+ T cells (15 to 60%), B cells (up to 20%), and macrophages was a characteristic finding. In conclusion, the results of this study suggest that demonstration of clonal TCR gene rearrangements and an aberrant phenotype, as well as demonstration of many admixed CD8+ T cells and B cells can be considered as useful additional criteria in the differentiation between pseudo-T-cell lymphomas and CTCLs.

Molecular analysis of hematopoietic colonies derived from chronic myeloid leukemia patients: interphase fluorescence in situ hybridization compared with RT-PCR.

In this study we compared interphase fluorescence in situ hybridization (I-FISH) with reverse transcription polymerase chain reaction (RT-PCR) for the molecular analysis of hematopoietic colonies derived from patients with chronic myeloid leukemia (CML). Molecular analysis of individual colonies is often performed to monitor purging efficacy in CML. We harvested individual colony-forming unit granulocyte-macrophage (CFU-GM) colonies. One half was analyzed with I-FISH, for the presence of bcr-abl fusion gene. The other half was analyzed with RT-PCR for the presence of the bcr-abl mRNA. We wanted to address the following questions: (1) is the bcr-abl gene always expressed in CFU-GM colonies and (2) which technique has to be preferred to analyze individual CFU-GM colonies? In total, 133 colonies, derived from six CML patients, could be analyzed both with I-FISH and RT-PCR. We found a positive correlation in 89% of the cases: 118 colonies showed the same results with both techniques. However, 15 of the 106 I-FISH-positive colonies were negative in the RT-PCR. Serial analysis of the cDNA derived from 22 colonies showed in each round of amplification 21-29% RT-PCR-negative but I-FISH-positive colonies. However, all I-FISH-positive colonies showed at least one positive RT-PCR, either in the first, second or third round of amplification. These results indicate that the bcr-abl gene is probably always transcriptionally active in CFU-GM colonies. Reliable analysis with RT-PCR is possible but likely to generate false negative results. We conclude that: (1) I-FISH offers a reliable alternative to RT-PCR for analyzing individual hematopoietic colonies and (2) results obtained with RT-PCR should only be interpreted with caution.

Expression of HOXC4, HOXC5, and HOXC6 in human lymphoid cell lines, leukemias, and benign and malignant lymphoid tissue.

Besides their regulatory role in embryogenesis, homeobox (HOX) genes are expressed in a specific manner in hematopoietic cell lineages, implying a role in the molecular regulation of hematopoiesis. Some HOX C cluster genes are found to be expressed in lymphoid cells of mice and humans. Their function and expression in normal hematopoiesis are still largely unknown. We have studied the mRNA expression of HOXC4, HOXC5, and HOXC6 in several stages of lymphocyte maturation by reverse transcriptase-polymerase chain reaction (RT-PCR) and RNA in situ hybridization (RISH). We examined CD34+/CD38low and CD34+/CD38high cells obtained from normal donor bone marrow (BM), a panel of 19 lymphoid cell lines, several types of leukemias and non-Hodgkin's lymphomas (NHL), and lymphocytes isolated from tonsillar tissue and peripheral blood (PB). HOXC4 and HOXC6 were found to be expressed during maturation in B- and T-lymphoid cells. The expression of each gene was found to be initiated at different cell maturation stages. HOXC4 transcripts were present in CD34+/CD38low cells, which are thought to comprise stem cells and noncommitted progenitor cells, and in subsequent stages to terminally maturated lymphoid cells. HOXC6 expression is initiated in equivalents of prothymocyte and pre-pre-B cell stage and remains present in mature cells. However, HOXC5 is only expressed in neoplastic cell lines and in neoplastic cells of NHL, but not in CD34+ BM cells, nor in resting or activated lymphoid cells isolated from tonsil, PB, or in leukemia cells. In cell lines, weak expression of HOXC5 is initiated in equivalents of pre-B cell and common thymocyte stage and is continuously expressed in mature cell lines. Semi-quantitative RT-PCR showed that expression levels of HOXC5 were much lower than those of HOXC4 and HOXC6; furthermore an increase of expression of HOXC4, HOXC5, and HOXC6 during lymphoid cell differentiation was demonstrated. Thus, mainly mature lymphoid cell lines and neoplastic cells of NHL do express HOXC5, in contrast to the lack of expression in normal lymphoid cells and leukemias. These findings suggest involvement of HOXC5 in lymphomagenesis.

Lack of granzyme expression in T lymphocytes indicates poor cytotoxic T lymphocyte activation in human papillomavirus-associated cervical carcinomas.

Changes in major histocompatibility complex (MHC) class I expression in neoplastic cells are frequently observed in human papillomavirus type 16 (HPV16)-associated cervical carcinomas. In order to investigate whether this affects cytotoxic T-cell (CTL) activation, 20 HPV16-positive cervical carcinomas with variable MHC expression were analyzed immunohistochemically for the expression of granzyme B and interleukin-2 receptor (IL-2R). The results revealed that most carcinomas show strong CD3+ T-lymphocyte infiltrates. In nine of these cases CD8+ cells outnumbered the CD4+ cells, whereas in the remaining cases equal amounts of CD4+ and CD8+ cells were found. Double staining revealed that CD3+ granzyme B+ cells were not detected in 19 out of 20 cervical lesions, whereas in one carcinoma an occasional cluster of granzyme B+ T cells was observed. Positive controls, including genital warts and renal allograft rejections, showed granzyme B+ T cells. In agreement with this observation was the extremely low frequency of IL-2R+ T cells in the carcinomas tested, while warts contained IL-2R+ lymphocytes. The data indicate that cytotoxic (CD8+) T cells in cervical carcinomas are not activated, as demonstrated by the lack of granzyme B and IL-2R expression in the T cells.

Functional expression of adhesion receptors and costimulatory molecules by fresh and immortalized B-cell non-Hodgkin's lymphoma cells.

Peripheral blood lymphocytes of a patient with follicular B-cell non-Hodgkin's lymphoma (B-NHL) were immortalized in vitro by Epstein-Barr virus (EBV). Eight cell lines were obtained (termed BNS1, BNS2-1 through BNS2-7), which showed a pattern of idiotypic (id) Ig surface expression and Ig JH and kappa gene rearrangement, identical to that of the parent cells (termed NS), confirming their neoplastic origin. Induction of allogeneic T-cell proliferation by NS cells was mediated by HLA-DR, leukocyte function-associated antigen-1 (LFA-1), LFA-3, B7-1/CD80, and CTLA4 and resulted in the upregulation (LFA-3, intercellular adhesion molecule-1 [ICAM-1], CD40) and induction (B7-1/CD80, B7-2/CD86, L16/activated LFA-1) of accessory molecules on NS cells. In turn, responder T lymphocytes were induced to express B7-1/CD80, B7-2/CD86, CD40 ligand (CD40L), ICAM-1, L16/activated LFA-1, and HLA-DR, reflecting bidirectional signaling between T lymphocytes and B-NHL cells. Preactivation of NS cells by EBV transformation or CD40 engagement resulted in enhanced expression of accessory molecules and abolished the requirement for accessory cells during allostimulation. These resting and activated clonal B cells will be useful in further dissecting the requirements for B-NHL costimulation.

Expression of the homeobox gene HOXC4 in keratinocytes of normal skin and epithelial skin tumors is correlated with differentiation.

Homeobox (HOX) genes share a highly conserved 183-bp sequence. The encoded proteins are capable of binding to specific DNA sequences and functioning as transcription factors. HOX genes play a critical role in the temporal and spatial differentiation of cells during embryogenesis. In several adult tissues, HOX genes are expressed in a constant, tissue-specific pattern, whereas in malignant tumors of these tissues an altered expression pattern was found. We investigated the expression of HOXC4 in adult normal skin by reverse-transcription polymerase chain reaction and non-radioactive RNA in situ hybridization. Moreover, HOXC4 expression was studied in various epidermal neoplasms (solar keratosis, six specimens; Bowen's disease, four; squamous cell carcinoma, nine; basal cell carcinoma, three) by RNA in situ hybridization. HOXC4 was found to be expressed in the suprabasal layers of the epidermis in normal skin specimens and the adjacent non-lesional epidermis of all other specimens. Atypical keratinocytes of solar keratoses and Bowen's disease as well as basaloid cells of basal cell carcinomas were negative. In squamous cell carcinoma, well differentiated areas with keratinization showed HOXC4 expression, whereas poorly differentiated areas were negative. Immunostaining with an antibody against cytokeratin 10, a marker of epidermal differentiation, was performed. A good correlation between the distribution pattern of HOXC4 and cytokeratin 10 in the lesions examined was found. These results suggest that HOXC4 is expressed mainly in differentiated keratinocytes. Lack of differentiation (as in neoplastic cells) is accompanied by downregulation of HOXC4 expression.