Determination of immunophenotypic aberrancies provides better assessment of peripheral blood involvement by mycosis fungoides/Sézary syndrome than quantification of CD26- or CD7- CD4+ T-cells.

BACKGROUND: Blood involvement by mycosis fungoides (MF)/Sézary syndrome (SS) influences prognosis and therapeutic decisions. MF/SS blood stage is currently determined by absolute CD4 + CD26- or CD4 + CD7-cell counts, which quantification method may overestimate MF/SS by including CD26- or CD7- normal CD4+ T-cells, or underestimate disease burden when MF/SS cells show incomplete loss of CD26 and/or CD7. Recently, through the standardization effort led by the International Clinical Cytometry Society (ICCS), recommendation was made to quantify MF/SS by enumerating immunophenotypically aberrant CD4+ T-cells, rather than CD26- or CD7- in isolation. METHODS: We compared these two quantitation methods in 309 MF/SS patients who had blood samples analyzed by flow cytometry immunophenotyping (FCI) over a 1-year period. RESULTS: Using the European Organization of Research and Treatment of Cancer (EORTC)/International Society for Cutaneous Lymphomas (ISCL) criteria, 221 (71.5%) patients had a blood stage corresponding to B0, 57 (18.4%) to B1, and 31 (10%) to B2. By FCI analysis, a total of 62 patients (20.0%) were found positive for MF/SS. Among EORTC B0 patients, 11/221 (5%) were positive by FCI (false negatives), and among EORTC Stage B1 patients, 35/57 (61%) were negative by FCI (false positives). Regarding patients positive for MF/SS cells by FCI, there was an overall excellent correlation (r = .999, p < .001) between the EORTC/ISCL method and FCI method; however, four (6.5%) patients would have an altered B stage between B0 and B1. CONCLUSION: The MF/SS cell quantification method using immunophenotypic aberrancies, as recommended by the ICCS, allows to distinguish MF/SS cells from background benign T-cells and enables for more accurate staging, especially among patients currently being considered to have B0 and B1 stage diseases.

Advanced human T-cell leukemia virus type 1 carriers and early-stage indolent adult T-cell leukemia-lymphoma are indistinguishable based on CADM1 positivity in flow cytometry.

We previously reported that the cell adhesion molecule 1 (CADM1) versus CD7 plot in flow cytometry reflects disease progression in human T-cell leukemia virus type 1 (HTLV-1) infection. In CD4(+) cells from peripheral blood, CADM1(-) CD7(+) (P), CADM1(+) CD7(dim) (D) and CADM1(+) CD7(-) (N) subpopulations are observed. The D and N subpopulations increase as asymptomatic HTLV-1 carriers (AC) progress to indolent adult T-cell leukemia-lymphoma (ATL) and the N subpopulation then expands in aggressive ATL. In the present study we examined whether the analysis can estimate the risk of developing ATL in advanced AC. Peripheral blood samples from AC (N = 41) and indolent ATL patients (N = 19) were analyzed by flow cytometry using the CADM1 versus CD7 plot for CD4(+) cells and inverse long PCR (clonality analysis) of FACS-sorted subpopulations. Almost all AC with a high HTLV-1 proviral load (>4 copies/100 cells) had a CADM1(+) (D + N) frequency of >10%. AC with 25% < CADM1(+) ≤ 50% contained expanded clones similar to smoldering-type ATL. In many patients in the 25% < CADM1(+) ≤ 50% group, the proportion of abnormal lymphocytes was distributed around the 5% line, which divides AC and smoldering-type ATL in Shimoyama's classification. In conclusion, the CADM1 versus CD7 plot is useful for selection of putative high-risk AC. The characteristics of some AC and smoldering ATL are said to be similar; however, long-term follow up is required and the clinical outcome (e.g. rate of transformation) of these cases should be used to determine whether to include them in the same clinical category.

The role of 9-O-acetylated ganglioside D3 (CD60) and {alpha}4{beta}1 (CD49d) expression in predicting the survival of patients with Sezary syndrome.

BACKGROUND: Sézary syndrome is a rare and very aggressive leukemic variant of cutaneous T-cell lymphoma characterized by extensive skin involvement and a malignant circulating CD4(+) T-cell clone which homes to the skin, over-expresses CD60, and lacks CD7, CD26 and CD49d. So far prognostic markers in this disease are limited to treatment with systemic steroids, age, serum lactate dehydrogenase, and a white blood cell count of 20×10(9)/L or higher: no other biological marker with prognostic value, especially related to malignant cells, has been described. DESIGN AND METHODS: We used flow activated cell sorting analysis to compare the distribution of the T-cell receptor-Vß repertoire and several surface molecules (CD7, CD26, CD49d and CD60) within the circulating CD4(+) T-cell population in 62 patients with Sézary syndrome, 180 with mycosis fungoides, 6 with B-cell lymphomas, and 19 with chronic eczema. We calculated the 5-year overall survival of patients with Sézary syndrome after first hospital admission using Kaplan-Meier product-limit estimates and hazard ratios from the Cox proportional hazards model. RESULTS: We found that both higher number of CD60(+) and lower number of CD49d(+) cells within circulating CD4(+) T cells at disease presentation were significantly associated with a lower probability of survival. An exceedingly high risk of death was observed for patients with a combination of a high proportion of CD4(+)CD60(+) cells (≥ 0.5×10(9)/L) and low proportion of CD4(+)CD49d(+) cells (<0.5×10(9)/L) (hazard ratio = 12.303, 95% confidence interval 1.5-95.9; P<0.02). In addition, a skewed usage of T-cell receptor-Vß subfamilies was observed in the circulating T-cell clone for 61.9% of all patients with Sézary syndrome, T-cell receptor-Vß 2 and 5.1 subfamilies being the most frequently represented (42.8%), followed by T-cell receptor-Vß 12 and 13.1. CONCLUSIONS: In this study we showed that up-regulation of CD60 and down-regulation of CD49d on circulating CD4(+) T cells are two useful markers for predicting a very poor outcome in patients with Sézary syndrome.

Duplication of isodicentric chromosome 21, idic(21)(p11.2), leading to pentasomy 21q in acute myeloid leukemia with multilineage dysplasia.

Isodicentric chromosome 21, idic(21)(p11.2), is a rare but recurrent cytogenetic aberration in acute lymphoblastic leukemia. We describe here a novel case of acute myeloid leukemia (AML) with double idic(21)(p11.2). A 35-year-old man was diagnosed as having de novo AML with multilineage dysplasia because of 30% myeloperoxidase-positive blasts and trilineage dysplasia in the bone marrow. Surface marker analysis revealed that the blasts were positive for CD7, CD13, CD33, CD34, and HLA-DR. Chromosome analysis and spectral karyotyping showed 47,XY,+21,idic(21)(p11.2)x2, leading to pentasomy 21q. Fluorescence in situ hybridization demonstrated two RUNX1 signals on the idic(21)(p11.2), resulting in a total of five RUNX1 signals in metaphase spreads and interphase nuclei. These results suggest that the idic(21)(p11.2) could be implicated also in the pathogenesis of AML through amplification of genes including RUNX1 located on 21q.

[Clinical and laboratory features of patients with CD34(+) acute promyelocytic leukemia].

OBJECTIVE: To explore the expression of CD34 in patients with acute promyelocytic leukemia (APL) and investigate the clinical and laboratory features of CD34(+) APL patients. METHODS: 262 APL patients diagnosed by chromosome analysis and/or fusion gene examination in the last five years were retrospectively analyzed in this study. To survey the expression of CD34 in those patients, all the cases were divided into two groups (CD34(+) APL vs. CD34(-) APL). The clinical features including age, gender, abnormal values of the peripheral hemogram before treatment, the complete remission (CR) rate and the incidence of DIC and laboratory data such as the results of morphology, immunology, cytogenetics and molecular biology (MICM) between those two groups were compared. RESULTS: Of the 262 APL patients, 38 (14.5%) cases were positive for CD34 expression. There were no statistically significant differences between CD34(+) APL and CD34(-) APL groups in gender and age (P > 0.05). Before treatment, the median level of WBC in CD34(+) APL was 25.92 x 10(9)/L, which was significantly higher than that of CD34(-) APL (5.3 x 10(9)/L, P < 0.05). CD34(+) APL by morphology classification were mostly of the subtypes M3b and M3v (65.8%), while these subtypes in CD34(-) APL (40.3%) were significantly less (P < 0.01). There were no statistically significant differences between the two groups compared in respect of complete remission (CR) rate and the incidence of DIC (P > 0.05). The expression level of CD34 in APL had correlation to the expression level of CD2, CD7 and CD117; the latter three phenotypes in CD34(+) APL were significantly higher than those in CD34(-) APL (P < 0.01). No significant difference was found between those two groups by chromosome analysis, but there was more PML-RAR-alpha transcript short form in CD34(+) APL than that in CD34(-) APL (P < 0.05). CONCLUSION: CD34(+) acute promyelocytic leukemia is a unique subtype of APL with different biological characteristics.

Acute rejection after liver transplantation: Is there a specific immunological pattern?

The aim of the study was to assess various T-cell subsets and cytokine secretion patterns both in liver tissue and in the peripheral blood of 24 liver transplant patients to assess possible specific immunological involvement in early acute rejection episodes after liver transplantation. Particularly, we studied CD4+ CD7+, CD8+ CD38+, and CD4+ CD25+ T cells by flow cytometry, as well as contemporaneously, interleukin (IL)-2 and IL-10 secretion by ELISpot to determine possible Th1-like immune responses and the immunomodulation expressed by Treg cells in acute liver rejection, respectively. As a control group we included patients transplanted without acute rejection. Early acute rejection within the first 4 weeks was proven histologically in 42% of patients. It was associated with a greater expression of CD4+ CD7+ and CD8+ CD38+ T cells in the liver than in the blood (P < .001). A contemporaneous reduced expansion of liver Treg cells was evident in patients with acute rejection (P < .001). Our data suggested that a preferential Th1-like immune mechanism operated in local fashion as characterized by a decreased presence in the liver and blood of Treg cells.

Diagnosis of mycosis fungoides: a comparative immunohistochemical study of T-cell markers using a novel anti-CD7 antibody.

Mycosis fungoides (MF) is the most common form of primary cutaneous T-cell lymphoma. In its early stage it may mimic benign dermatoses both on a clinical and histologic basis. MF usually expresses CD3 and CD4 (T-cell) markers. CD7 is expressed on about 90% of CD4 T cells and is often deficient on malignant T cells. Thus, CD7 may be useful in evaluating the nature of dermal lymphoid infiltrates. The aim of this study was to evaluate the usefulness of immunohistochemical detection of T-cell markers on paraffin-embedded sections, CD3 and CD7 (clone CBC.37), in the differential diagnosis of MF and benign dermatoses. Forty-two patients with diffuse dermal T-lymphocytic infiltrates were selected. Previous clinicopathologic correlation and follow-up had established the diagnosis of MF in 31 patients and benign dermatoses in 11. The mean value of stained cells in MF was 86.45% for CD3 and 53.09% for CD7 (P<0.001); in benign dermatoses it was 79.09% for CD3 and 73.63% for CD7 (P=0.669). CD7 immunolabeling was significantly lower in the MF group (P=0.048). A semiquantitative evaluation revealed a considerable loss of CD7 immunolabeling in comparison with CD3 in patients with MF. The authors conclude that CD7 study may represent a valuable tool in the distinction between inflammation and neoplasia in T-lymphoproliferative skin disorders.

Interleukin-10 and tumor necrosis factor-alpha: model of immunomodulation in multiple sclerosis.

OBJECTIVES: The mechanisms involved in the pathogenesis of relapsing-remitting multiple sclerosis are still unclear. The aim of the present study was to evaluate both cerebrospinal fluid (CSF) CD4+ CD7+ T cells and peripheral blood (PB) interleukin-10 (IL-10) as well as tumor necrosis-alpha (TNF-alpha) levels in patients with definite multiple sclerosis of the relapsing-remitting type. METHODS: To assess the above-mentioned cytokine levels we performed our test by the means of ELI-spot assay; the T-helper cell subset was assayed using flow cytometry. RESULTS: PB IL-10 levels of multiple sclerosis (MS) patients in remission were significantly (p<0.001) higher than in MS patients in the active phase. There was significant and increased evidence of TNF-alpha levels only in the MS patients in the active phase. CD4+ CD7+ T cells, characterized by a preferential Th1-like cytokine profile, were detectable only in seven patients in the active phase without evidence of a statistical significance with respect to cytokine levels. CONCLUSION: The data indicate that the production of different cytokines characterized the expression of relapsing-remitting MS. The data also suggest that is it possible to control MS using the regulatory cytokine balance.

Myeloid/NK cell precursor acute leukemia lost both CD13 and CD33 at first diagnosis.

It has been reported that malignancies of natural killer (NK) cell precursors, which are present in both myeloid and lymphoid antigens, are characterized by immature lymphoblastoid morphology with CD7+, CD33+ and CD56+ phenotype. Here, we report a 18-year-old man who was diagnosed with CD33- and CD13- NK cell precursor acute leukemia at first diagnosis. Following a 3-year remission state, he had a relapse as a testicular tumor and CD33+ myeloid/NK cell precursor acute leukemia after allogenic BMT. This case suggests that myeloid antigens are not necessary for diagnosis of myeloid/NK cell precursor acute leukemia.

Absence of CD26 expression is a useful marker for diagnosis of T-cell lymphoma in peripheral blood.

We report flow cytometric characterization of surface CD26 expression in 271 peripheral blood samples from 154 patients evaluated for the presence of a T-cell lymphoproliferative disorder, primarily mycosis fungoides/Sézary syndrome (MF/SS). The presence of morphologically identifiable tumor cells on peripheral blood smears was the criterion for lymphomatous involvement. In 66 of 69 samples from 28 patients, we identified an abnormal CD26-/dim T-cell population that was distinct from the variable CD26 expression seen in normal peripheral blood T cells. This population was CD26- in 23 patients and weakly CD26+ in 5 patients. CD7 was more variably expressed in MF/SS tumor cells, allowing recognition of a distinct, quantifiable abnormal T-cell population in only 34 of 69 involved samples. An increased CD4/CD8 ratio and lower surface expression of CD4 in tumor cells also helped separate the CD26-/dim atypical population for quantification. In 35 blood samples from other types of T-cell tumors, tumor cells in 10 of 11 morphologically involved cases showed absent/dim CD26. Although capable of detecting abnormalities in most cases of MF/SS, CD7 expression does not provide as clear a separation of the neoplastic population and can be replaced by CD26 staining in routine peripheral blood flow cytometric screening of MF/SS patients.

Identification of a novel, human multilymphoid progenitor in cord blood.

The earliest stages of lymphoid commitment from human pluripotent hematopoietic stem cells have not been defined. A clonogenic subpopulation of CD34(+)CD38(-) cord blood cells were identified that expressed high levels of the CD7 antigen and possessed only lymphoid potential. CD34(+)CD38(-)CD7(+) (CD7(+)) cells uniformly coexpressed CD45RA and HLA-DR; c-kit and Thy-1 expression was absent to low. Clonal analysis demonstrated that single CD7(+) cells could generate B cells, natural killer cells, and dendritic cells but were devoid of myeloid or erythroid potential. In contrast, control CD34(+)CD38(-)CD7(-) (CD7(-)) cells generated both lymphoid and myelo-erythroid cells. The lymphoid potential (generation of lymphoid progeny in bulk and single cell cultures) of CD7(+) cells was equivalent to that of the pluripotent CD7(-) cells. RNA expression studies showed that CD7(+) cells expressed PU.1 and GATA-3, but did not express Pax-5, terminal deoxynucleotide transferase, or CD3epsilon. In contrast to the previously described murine common lymphoid progenitor, the alpha chain of the receptor for interleukin-7 was not detected by fluorescence-activated cell sorting analysis or RNA polymerase chain reaction in CD7(+) cells. These studies identify a clonogenic lymphoid progenitor with both B-cell and natural killer cell lineage potential with a molecular profile that suggests a developmental stage more primitive than previously identified lymphoid progenitors. The CD7(+) phenotype distinguishes primitive human lymphoid progenitors from pluripotent stem cells, thus allowing the study of regulation of early human lymphopoiesis and providing an alternative to pluripotent stem cells for genetic manipulation and transplantation. (Blood. 2001;97:3683-3690)

Characterization of dendritic cell differentiation pathways from cord blood CD34(+)CD7(+)CD45RA(+) hematopoietic progenitor cells.

To better characterize human dendritic cells (DCs) that originate from lymphoid progenitors, the authors examined the DC differentiation pathways from a novel CD7(+)CD45RA(+) progenitor population found among cord blood CD34(+) cells. Unlike CD7(-)CD45RA(+) and CD7(+)CD45RA(-) progenitors, this population displayed high natural killer (NK) cell differentiation capacity when cultured with stem cell factor (SCF), interleukin (IL)-2, IL-7, and IL-15, attesting to its lymphoid potential. In cultures with SCF, Flt3 ligand (FL), granulocyte-macrophage colony-stimulating factor (GM-CSF), and tumor necrosis factor (TNF)-alpha (standard condition), CD7(+)CD45RA(+) progenitors expanded less (37- vs 155-fold) but yielded 2-fold higher CD1a(+) DC percentages than CD7(-)CD45RA(+) or CD7(+)CD45RA(-) progenitors. As reported for CD34(+)CD1a(-) thymocytes, cloning experiments demonstrated that CD7(+)CD45RA(+) cells comprised bipotent NK/DC progenitors. DCs differentiated from CD7(-)CD45RA(+) and CD7(+)CD45RA(+) progenitors differed as to E-cadherin CD123, CD116, and CD127 expression, but none of these was really discriminant. Only CD7(+)CD45RA(+) or thymic progenitors differentiated into Lag(+)S100(+) Langerhans cells in the absence of exogenous transforming growth factor (TGF)-beta 1. Analysis of the DC differentiation pathways showed that CD7(+)CD45RA(+) progenitors generated CD1a(+)CD14(-) precursors that were macrophage-colony stimulating factor (M-CSF) resistant and CD1a(-)CD14(+) precursors that readily differentiated into DCs under the standard condition. Accordingly, CD7(+)CD45RA(+) progenitor-derived mature DCs produced 2- to 4-fold more IL-6, IL-12, and TNF-alpha on CD40 ligation and elicited 3- to 6-fold higher allogeneic T-lymphocyte reactivity than CD7(-)CD45RA(+) progenitor-derived DCs. Altogether, these findings provide evidence that the DCs that differentiate from cord blood CD34(+)CD7(+)CD45RA(+) progenitors represent an original population for their developmental pathways and function. (Blood. 2000;96:3748-3756)

Reconstitution of lymphocyte subpopulations after paediatric bone marrow transplantation.

We prospectively studied the reconstitution of lymphocyte subpopulations in a group of 22 children, who survived disease-free at least 6 months after allogeneic BMT for a haematological malignancy. Absolute counts of total lymphocytes, B lymphocytes, T lymphocytes, and CD4+ helper T lymphocytes reached the 5th percentile (p5) of age-matched reference values within 6 months after BMT in 15, 17, 7 and 2 patients, respectively. In particular, CD4+ helper T lymphocyte reconstitution was very slow. Unexpectedly, CMV reactivation had a profound positive influence upon the number of CD4+ helper T lymphocytes in the children. In five patients, absolute B lymphocyte counts above the 95th percentile were reached from 6 months after BMT onwards, mimicking normal ontogeny. Unlike normal ontogeny, the percentages of helper T lymphocytes expressing the 'naive' CD45RA isoform were low and those expressing the 'memory' CD45RO isoform were high in the first 3 months after BMT, as described before. Thereafter, the CD45RA:CD45RO ratio slowly normalised. Also, CD7 expression was absent on up to 90% of T lymphocytes in the first months after BMT, and on a steadily decreasing percentage thereafter, as recently described in adults. However, the absolute counts of CD45RO+/CD4+ and CD7-/CD4+ helper T lymphocytes did not change significantly. So, we found no evidence of peripheral expansion of previously primed donor-derived 'memory' T lymphocytes during the follow-up period which spanned 1-18 months after BMT. The absolute counts of 'naive' CD45RA+ helper T lymphocytes did not show a faster increase after BMT than in adults, despite the presumed presence of a non-involuted thymus in children. Bone Marrow Transplantation (2000) 25, 267-275.

The human immunodeficiency virus (HIV)-type 1 coreceptor CXCR-4 (fusin) is preferentially expressed on the more immature CD34+ hematopoietic stem cells.

In synergy with the CD4 antigen, the chemokine receptor CXCR-4 functions as a coreceptor for T-cell-tropic HIV-1 strains. Using two- and three-color immunofluorescence analysis, we examined the expression of CXCR-4 on CD34+ cells in 21 samples obtained from leukapheresis (LP) products of cancer patients who underwent G-CSF-supported cytotoxic chemotherapy. In addition, eight samples from bone marrow (BM) were obtained. CXCR-4 was expressed on the surface of CD34+ cells from samples of both hematopoietic sources. The mean proportion of CD34+/CXCR-4+ cells from LP products was 1.7-fold greater in comparison with those from bone marrow (65.9+/-4.1% vs. 37.5+/-8.6% [+/- SEM], p < 0.05). For an intraindividual comparison, LP products and bone marrow from six patients were obtained on the same day, confirming the significantly greater proportion of CD34+ cells coexpressing CXCR-4 cells in LP products. In order to examine whether the CXCR-4 expression was related to the stage of maturation and differentiation of CD34+ cells, six samples from LP products and four samples from bone marrow were assessed using three-color immunofluorescence analysis. We found that the subset of CD34+/CD38low and CD34+/HLA-DRlow cells representing a population of more immature progenitor cells were brightly positive for CXCR-4, while there was a decrease in the level of CXCR-4 expression in the population of CD34+/HLA-DRbright and CD34+/CD38bright cells. Based on the assessment of ten LP products, we found that the mean proportion of CD34+ cells coexpressing CD4 and CXCR-4 was 6.2+/-2.3% [+/- SEM], suggesting that a small population of CD34+ cells are, in principle, susceptible for an infection with T-cell-tropic HIV-1 strains. In conclusion, our data suggest that CXCR-4 is present on the surface of hematopoietic progenitor cells--particularly more primitive CD34+ cells. CXCR-4 could play a role in the homing of CD34+ cells to stromal elements of the bone marrow via its natural ligand stromal-derived factor-1 (SDF-1).

[Prognostic significance of CD7 expression in adult acute myeloid leukemia].

To evaluate the prognostic significance of CD7 expression in de novo acute myeloid leukemia (AML), we studied 63 patients with AML who had been admitted to our hospital between September 1989 and January 1996. Even of the patients were later eliminated from the study (9 due to insufficient surface marker analyses, and 2 due to early death). The remaining 52 patients (median age: 42.5 years) were evaluated for morphologic subtype, immunophenotypic classification, complete remission (CR), disease-free survival (DFS) and overall survival (OS). All 52 patients were grouped by the French-American-British classification system: 10 as M1, 16 as M2, 11 as M3, 8 as M4, 5 as M5, and 2 as M6. Ten of the patients expressed CD7 on their leukemia cells (positive rate > or = 25) and were classified as CD7(+)AML, with morphological subtypes as follows: 3 as M1, 6 as M2, and 1 as M3. Thirty-three of the 42 patients with CD7 + AML (78.6%) and 6 of the 10 patients with CD7 + AML (40%) achieved CR. DFS and OS rates for the patients with CD7(+)AML were 22.1% and 35.4%, respectively; those for the CD7(+)AML patients were 53.3% and 44.4%, respectively. No significant differences in gender hematological findings, clinical manifestations such as hepatosplenomegaly, lymphadenopathy, or incidence of central nervous system involvement, CR rate, and DFS distinguished patients with CD7(+)AML from those with CD7(+)AML. These suggest that CD7 expression is unlikely to be a prognostic factor in AML.

CD7 positive hematopoietic progenitors and acute myeloid leukemia and other minimally differentiated leukemia.

Acute leukemias are believed to arise from unregulated proliferation of hematopoietic cells and loss of the ability to differentiate. Studies on the immunophenotypes of leukemic cells are very helpful for the understanding of antigen expression during normal hematopoiesis. CD7 antigen has until recently been considered to be a T-cell marker but has been found to be expressed by leukemic cells from some acute myeloid leukemia (CD7+ AML) and the normal putative counterparts of blasts from CD7+ AML can be found in human fetal livers. These double CD7 and myeloid antigen (CD13 and/or CD33) positive progenitors tend to lose their CD7 expression, while retaining their myeloid characteristics, after in vitro culture with the differentiation-inducing agent phorbol ester (TPA). This suggests that the cells are probably committed to the myeloid cell lineage and that CD7 is only transiently expressed in the early differentiation stage. On the other hand, there is a subset of CD7+ hematopoietic precursors which lack mature myeloid and T-cell antigens and have the potential to differentiate to both T-lymphoid and myeloid cells. These cells may in fact be the common myeloid-T lymphoid progenitors and represent the normal counterparts of acute undifferentiated leukemia or minimally differentiated T-cell acute lymphoblastic leukemia.

Quantitative analysis of leukocyte membrane antigen expression on human fetal and cord blood: normal values and changes during development.

We studied the antibody binding capacity (ABC) of various cell-surface antigens in normal human fetuses and term neonates on lymphocyte, monocyte, and polymorphonuclear (PMN) cells by quantitative flow cytometry also designated by quantimetry. Analysis of changes of expression level on these leukocytes during the developmental process was also investigated. The results indicated that the ABC values of most studied markers change during the maturational process. The ABC of lymphocyte-associated antigens studied such as CD5 and CD7 showed only a decrease from fetus to adult, whereas according to the type of molecule on monocyte and PMN there was either an increase or a decrease of ABC values dependent on the stage of the developmental process, from fetus to neonate or from neonate to adult. However, the ABC values of leukocyte membrane antigens such as CD16, CD46, and CD55 on all leukocytes and CD11b, CD11c, and CD35 on myeloid cells did not change. Their expression level was already mature in fetuses compared with adult cells. In addition, in this quantimetric approach, the analysis of the results for CD11a and CD8 suggested that the changes of CD11a expression level on lymphocyte subsets can depend on one mechanism, whereas there are probably at least two for CD8. Furthermore, the expression patterns of CD5, CD7, and CD11a change during maturation. We concluded that, even if the neonate response pattern to immunological challenge differs from an adult and this is based primarily on the relative numbers and functional activity of lymphocyte T subsets (especially TH1/TH2) and their cytokine profiles, these quantitative and qualitative phenotypical differences might also contribute to explain the functional peculiarities of leukocyte fetal and cord blood cells. All these findings support the notion of immaturity and maturity of ABC expression.

Biochemical analysis of plasma-soluble invariant chains and their complex formation with soluble HLA-DR.

The invariant chain (CD74) is preferentially localized in the cytoplasm and regulates the loading of exogenous derived peptides into HLA class II heterodimers. In addition, a small proportion of CD74:class II complexes is also expressed on the cell surface. We identified and quantified soluble CD74 (sCD74) molecules in the plasma and sCD74:sHLA-DR complexes by ELISA. EDTA plasma samples from 86 healthy probands were analyzed. sCD74 could be detected in all samples with a mean concentration of 1.14 relative units +/- 1.04 SD (range 0.17-4.31). Approximately 10% of the samples had increased amounts of sCD74 (>3.0 relative units). Complexes of sCD74 and sHLA-DR were detected in all samples and their quantities were positively correlated (r=0.83, p<0.001) with the sCD74 concentrations. SDS-PAGE analysis of plasma samples with high sCD74 concentrations (>3.0 relative units) revealed four isoforms of sCD74 with molecular weights of 45, 43, 35, 31 kDa corresponding to known sizes of intracellular CD74. However, only molecular weights of the 45 and 43 kDa isoforms of sCD74 are found complexed with sHLA-DR. Our data demonstrate, that CD74 molecules are present in their soluble form in the plasma of healthy probands and form complexes with soluble HLA-DR molecules.