Immunohistochemical analysis of Hodgkin's disease in Kampala, Uganda

BACKGROUND

Histopathological examination remains crucial for diagnosis and classification of Hodgkin's disease (HD) but poses problems when characteristic features of HD are not present and hence the value of immunohistochemistry. Experience with immunohistochemistry in developing countries is limited due to cost.

OBJECTIVE

To describe the immunophenotypic and histologic types of Hodgkin's disease in Kampala, Uganda

DESIGN

A cross-sectional study.

SETTING

Makerere University Medical School, Department of Pathology.

METHODOLOGY

Two hundred formalin fixed, paraffin- embedded biopsies, which had been previously diagnosed as Hodgkin's disease in the Makerere University, Department of Pathology from 1980--2000, were re-assessed with haematoxylin and eosin. The sections were then subjected to immunohistochemistry using monoclonal antibodies: leucocyte common antigen (CD45), antibodies to Reed-Sternberg cells (CD15, CD30) and to B cells (CD20).

RESULTS

Of the 200 biopsies, 171 (71.3%) were diagnosed as Hodgkin's disease using immunohistochemistry. The mean age of the 171 cases was 26.1(SD 16.2) years; mode 20.0; median 22.5 years. The 15-24 year age group was most affected (47.2%). There were more males (65.9%) than females and most were Baganda who are the main tribe in the central region of Uganda. Mixed cellularity (35.7 %) and lymphocyte depleted (24.6 %) HD were the commonest histological types. Classic HD (CD30, CD 15, CD20, CD45) was the most commonest (77.8%) immunophenotype.

CONCLUSION

Classic Hodgkin's disease (CD30, CD 15, CD20 and CD45) is the most commonest immunophenotype in Kampala, Uganda, and mixed cellularity and Iymphocyte depleted are the main histologic subtypes.

Establishment of a microplate assay for flow cytometric assessment and it is use for the evaluation of age-related phenotypic changes in canine whole blood leukocytes

The effectiveness of flow cytometric assays for canine use is still requiring standardization. Despite several studies using purified mononuclear cells, no methodology or reference ranges are available for immunophenotyping of whole blood leukocytes (WBL). Fresh and pre-fixed WBL were used to identify cell-subsets, (Thy-1(+)/CD5(+)/CD4(+)/CD8(+)/CD21(+) and CD14(+)) and measure MHC-II, CD45RA/CD45RB expression. We described here an efficient method for fast quantification of canine-WBL, using pre-fix in a microplate assay, which allows long-term sample storage prior to phenotyping. Decreased percentage of CD5(+)-T-cells within the lymphocyte-gate and increased percentage of CD21(+)-B-cells were observed in young animals, which led to higher T/B cell ratios in middle-aged dogs. Lower numerical counts of Thy-1(+), CD4(+), CD8(+) and CD21(+) lymphocyte were observed when compared to young animals. In addition, we identified an age-related decline of MHC-II/CD45RA expression by lymphocytes. We proposed an improved method for phenotyping of canine peripheral blood mononuclear cells (PBMC) that has significant use for researchers and veterinary clinicians. The hematological changes of senescence previously identified on PBMC could be adequately reproduced on features identified by whole blood. Furthermore, this study supplies normal range references as baseline standards for clinical purposes, besides specific immunological parameters to monitor canine aging process.

Gammadelta and alphabeta T-cell acute lymphoblastic leukemia: comparison of their clinical and immunophenotypic features

Gammadelta-T-cell acute lymphoblastic leukemia (ALL) is a rare variant of ALL. The comparison of some clinical and laboratory features in children and adults with gammadelta-T-ALL or alphabeta-ALL showed that in gammadelta-T-ALL the CD45RAEth/CD45RO+ phenotype was predominant, the hemoglobin concentration was lower in children and the presence of splenomegaly and the white cell counts was higher in adults.

Flow cytometry identification and characterization of mononuclear cell subsets in the neotropical primate Saimiri sciureus (squirrel monkey)

BACKGROUND

The neotropical primate squirrel monkey is used in many areas of biomedical research including neuroendocrinology, immunology and infectious diseases. However, research has been hampered by the lack of immunological tools for this primate.

METHODS

A series of 67 commercially available monoclonal antibodies to human CD antigens or cytokines were tested on Saimiri mononuclear cells and the specificity was assessed by double staining using flow cytometry.

RESULTS

Monoclonal antibodies defining the main mononuclear cells subsets (monocytes, B, T, including CD4 and CD8 T cells) as well as activation markers have been identified. The conditions to specifically identify the various cell subsets using two color flow cytometry and establish their relative proportions have been set-up. We also have established normal values of the main circulating mononuclear cell subsets for adult Saimiri sciureus monkeys from the breeding unit of Institut Pasteur in French Guiana. The distribution between spleen, blood and lymph nodes has been compared.

CONCLUSIONS

These tools allow documenting the phenotype of most Saimiri mononuclear cell subsets and assessing their activation level. This opens new perspectives for vaccinology and immunopathology research in this experimental non-human primate host, in particular for malaria research.

Impaired Dendritic Cell Immunophenotype and Function in Heart Transplant Patients Undergoing Active Cytomegalovirus Infection

BACKGROUND

Human cytomegalovirus (HCMV) infects dendritic cells (DCs) in vitro and inhibits their maturation properties and their ability to stimulate T-cell proliferation and cytotoxicity. This study analyzed HCMV infection of DCs in vivo.

METHODS

We compared blood DCs and monocyte-derived DCs from heart-transplant patients undergoing an acute HCMV infection with DCs obtained from HCMV-negative transplant patients. Diagnosis of active HCMV infection was established by antigenemia test.

RESULTS

We detected viral RNA and antigens in defined DC subsets obtained from patients undergoing an active HCMV infection. In addition, we found an impaired immunophenotype in immature DCs from HCMV-positive subjects and a reduced ability of mature DCs from the same group of patients to stimulate allogenic T-cell proliferation.

CONCLUSIONS

The impaired immunophenotype and function detected in DCs from transplant patients undergoing an active HCMV infection may be a mechanism used by the virus to interfere with early immune functions and thereby contributing to the HCMV-induced immunosuppression in these patients.

Relative contributions of enzyme cytochemistry and flow cytometric immunophenotyping to the evaluation of acute myeloid leukemias with a monocytic component and of flow cytometric immunophenotyping to the evaluation of absolute monocytoses

We evaluated the contributions of enzyme cytochemical stains and flow cytometric immunophenotyping (FCI) data to detection of monocytic cells (MCs) in acute myelomonocytic and acute monocytic leukemias (AMMLs and AMoLs) and compared FCI findings in AMoL, chronic myelomonocytic leukemia (CMML), and normal peripheral blood (PB) and bone marrow (BM) monocytes to classify and evaluate absolute monocytoses (AMs). We reviewed 10 AMMLs and 6 AMoLs with a-naphthyl-acetate esterase (ANAE) and a-naphthyl-butyrate esterase stains and a complete FCI profile and compared FCI data for 6 AMoLs, 7 CMMLs, 2 AMs, and normal monocytes. We confirmed increased sensitivity of ANAE staining to FCI data in detecting MCs in AMML and AMoL. CD14 was insensitive for confirming MCs; other characteristic markers of MCs were absent or partially lost in AMML and AMoL. Aberrant expression of CD56 (detected in 50% of AMMLs and AMoLs), CD34, and CD117 indicated malignancy. The mature MCs of the CMMLs revealed variable FCI abnormalities (partial loss of CD13, CD14, and CD15; expression of CD56), as in the monoblasts of AMoL. These FCI abnormalities in morphologically mature MCs might indicate markers for CMML. AMs revealed FCI abnormalities, indicating clues to their correct classification as CMML.

Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma With Trisomy 12 and Focal Cyclin D1 Expression: A Potential Diagnostic Pitfall

Chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) and mantle cell lymphoma usually are distinctly different in regard to clinical presentation, morphology, immunophenotype, and molecular/genetic findings. In spite of this, select cases may show overlapping characteristics and represent a diagnostic challenge. Cyclin D1 immunohistochemical staining is usually envisioned as a definitive method for resolving this differential diagnosis, with positivity supporting a diagnosis of mantle cell lymphoma. We report a case involving a 58-year-old man with a diagnosis of CLL/SLL for several years. A lymph node excision was performed after increased adenopathy was noted in the cervical region. The excised lymph node showed typical morphologic findings of CLL/SLL, including the presence of characteristic proliferation centers. Cyclin D1 staining, using 3 different antibodies, was present in scattered prolymphocytes and paraimmunoblasts, mostly within proliferation centers. Fluorescence in situ hybridization and conventional cytogenetics demonstrated trisomy 12 and an absence of t(11;14) in lymph node tissue. Focal cyclin D1 expression by immunohistochemistry in nodal CLL/SLL is quite unusual and is discussed as a potential diagnostic pitfall.

Immunophenotyping characteristic of the major lymphocyte populations and subpopulations in patients during salmonella infection

AIM

To study the quantitative changes in the major lymphocyte populations and subpopulations in the peripheral blood of patients during salmonellosis and find correlations of these changes with disease severity and bacterial clearance.

MATERIAL AND METHODS

The study included 24 adult patients with culture-proven gastrointestinal salmonellosis. Flow-cytometry was used to identify CD19+ (B lymphocytes), CD2+ (total T lymphocytes), CD3(+)CD4+ (helper T cells), CD3(+)CD8+ (suppressor/cytotoxic T lymphocytes), CD4(+)CD29+ and CD4(+)CD45(-)RA+ (helper/ inducer subpopulation and naive Tlymphocytes) in the acute and the convalescent phases of disease. The absolute number and percentage of cells in 1 microl of peripheral blood were also determined. Immunophenotype analysis was conducted on an EPICS XL-MCL flow cytometer, Coulter, USA using monoclonal antibodies produced by the same firm.

RESULTS

T and B lymphocytes and the immunocompetent T cells were slightly decreased transiently in the acute phase of the disease. Helper T lymphocytes were slightly increased with a significant increase observed of helper/inducer cells and decrease of the naive T lymphocytes.

CONCLUSION

The increase of B lymphocytes at the height of salmonellosis bears additionally a diagnostic significance in determining the severity of the disease while the increase of the helper T lymphocytes can be a prognostic marker of early bacterial clearance.

[Immunoglobulin heavy chain gene rearrangements in the monoclonal gammopathies]

Plasma cell neoplasia occurs as a result of the expansion of an immunoglobulin-secreting B-cells clones, known as monoclonal component or M component. Malignant neoplasias include multiple myeloma and Waldenstrom macroglobulinemia, while premalignant conditions comprise monoclonal gammopathies of unknown significance (MGUS). MGUS present a monoclonal component with no signs of multiple myeloma, Waldenström macroglobulinemia, primary amyloidosis or other disorders. Pathological, radiological and clinical features are required for the diagnosis. Approximately 25% of patients with MGUS will become multiple myeloma, primary amiloidosis, macroglobulinemia, or other lymphoproliferative disease, which would be a premyelomatous condition. The objective of this study was to determine the clinical implications of immunophenotyping by flow cytometry and of the detection of clonality by molecular biology. A total of 32 patients were studied. Seven of them were diagnosed with multiple myeloma, and 25 with monoclonal gammopathy under study. These 32 patients were divided into four groups, based on their clinical data and flow cytometry outcome. In patients with non-diagnostic flow cytometry detection of immunoglobulin heavy chain gene rearrangements by PCR was performed, and monoclonality was found in 59% of the cases. The study of immunoglobulin heavy chain gene rearrangements by molecular biology allows a more sensitive detection of clonality.

IgVH mutations in blastoid mantle cell lymphoma characterize a subgroup with a tendency to more favourable clinical outcome

Mantle cell lymphoma (MCL) is associated with a very unfavourable clinical course. This is particularly true for mantle cell lymphoma of the blastoid subtype (MCL-b). In order to define prognostic factors, we analysed the impact of immunoglobulin heavy chain variable (IgV H) gene somatic hypermutations on clinical outcome in a series of 21 cases of morphologically, phenotypically, and genotypically well-characterized MCL-b. Testing and estimation were performed using log-rank statistics and displayed on Kaplan-Meier graphs. Thirteen of 21 cases of MCL-b revealed a homology rate of > or = 99% compared to IgV H germ-line sequences in the databases and were scored as non-mutated. Eight of 21 cases (38%) of MCL-b were mutated. In MCL-b the mutation frequency was usually low and the mutation pattern was only rarely antigen-selected, in contrast to a control group of 11 cases with morphologically almost identical, but phenotypically and genotypically clearly distinguishable, diffuse large B cell lymphoma, derived, most likely, from germinal centre B cells. In our series of 21 MCL-b, positive IgV H mutational status, irrespective of varying homology thresholds, had no statistically significant prognostic impact on event-free or overall survival. However, mutated MCL-b tended to present more frequently at an earlier stage and without bone marrow involvement and to show lower rates of relapse and death, resulting in a more favourable clinical outcome.

Advantages of flow cytometry immunophenotyping for the diagnosis of central nervous system non-Hodgkin's lymphoma in AIDS patients

BACKGROUND

Neurological disorders are common in HIV-infected patients. Central nervous system (CNS) lymphoma should always be considered because it is an important cause of morbidity and mortality.

OBJECTIVES

To investigate the clinical utility of flow cytometry immunophenotyping (FCI) in diagnosing or discarding leptomeningeal involvement in HIV-infected patients and to compare its sensitivity with that of conventional cytological methods.

METHODS

Fifty-six cerebrospinal fluid (CSF) samples from 29 HIV-infected patients were independently evaluated by flow cytometry and cytology. The description of an aberrant immunophenotype was the criterion used to define the malignant nature of any CSF cell population.

RESULTS

FCI and cytology gave concordant results for 48 of the 56 CSF samples studied: 37 were negative for malignancy and 11 had evidence of CNS lymphoma. Discordant results were obtained for eight CSF samples, and the accuracy of the FCI findings could be demonstrated for four CSF samples described as positive for malignancy according to the FCI criteria.

CONCLUSIONS

A high level of agreement was found between the results obtained using the two methods, but FCI gave at least 25% higher sensitivity than conventional cytomorphological methods for the detection of malignant cells. This advantage suggests that, in case of negative flow cytometry results, disorders other than non-Hodgkin's lymphoma should be strongly considered.

HLA-DP4 expression and immunity to NY-ESO-1: correlation and characterization of cytotoxic CD4+ CD25- CD8- T cell clones

NY-ESO-1 is one of the most immunogenic cancer antigens known to date, eliciting spontaneous immune responses in approximately 50% of patients with NY-ESO-1+ cancers. Spontaneous CD4+ and CD8+ T cell responses were found in patients with detectable NY-ESO-1 serum antibody, indicating an integrated type of immune response induced by NY-ESO-1+ malignancies. A close association between spontaneous NY-ESO-1 immunity and the HLA-DP4 allele was suggested in a recent study. To address these results, we assessed the NY-ESO-1 antibody and HLA-DP4 status of 102 patients with NY-ESO-1+ malignancies. However, no correlation between HLA-DP4 and NY-ESO-1 immunity was found. To explore the role of HLA-DP4-restricted CD4+ T cells in cancer immunity, we established HLA-DP4- restricted NY-ESO-1-specific CD4+ T cell clones by limiting dilution and repeated stimulation with NY-ESO-1 peptide p157-170 from NY-ESO-1 seropositive patients. A subset of CD4+ T cell clones was reactive with naturally processed NY-ESO-1 presented by autologous DCs that were pulsed with recombinant NY-ESO-1 protein, lysates of NY-ESO-1-expressing tumor cell lines, or transduced with recombinant NY-ESO-1 viral constructs in ELISPOT assays. Three different CD4+ T cell clones were used to mediate the specific lysis of allogeneic HLA-DP4+ Epstein-Barr virus-transformed B cells (EBV-B) pulsed with NY-ESO-1 p157-170. The Th1 phenotype and effector functions of the CD4+ T cell clones described here provide an important rationale for the activation of antigen-specific CD4+ T cells along with CD8+ T cells in cancer vaccination strategies.

Are alterations of lymphocyte subpopulations in polymicrobial sepsis and DHEA treatment mediated by the tumour necrosis factor (TNF)-alpha receptor (TNF-RI)? A study in TNF-RI (TNF-RI(-/-)) knock-out rodents

Sepsis is associated with depression of T cell-dependent immune reactivity with proinflammatory cytokines, such as tumour necrosis factor (TNF)-alpha, playing an important role. Recent investigations describe an association between these immunological alterations and disturbances of the endocrine system, related most frequently to sex steroid hormones. Dehydroepiandrosterone (DHEA), one of the most abundant adrenal sex steroid precursors, seems to have a protective immunological effect towards septic insults. In this study, both the role of TNF-receptor I (RI) and possible interactions in the protective role of DHEA were investigated in a murine model of polymicrobial sepsis. Polymicrobial sepsis was induced by caecal ligation and puncture (CLP) in a murine model. The effects of DHEA on survival, clinical parameters and cellular immunity (T lymphocytes and natural killer (NK) cells) were investigated. CLP was performed in genetically modified TNF-RI knock-out (TNF-RI(-/-)) and genetically unmodified (wild-type, WT) mice. DHEA application was associated with a decrease in the mortality rate in WT animals. A mortality rate of 91.7% was observed in TNF-RI(-/-) mice after CLP. This mortality rate was reduced to 37.5% by the application of DHEA. In sham-operated TNF-RI(-/-) animals, a significantly higher proportion of NK cells within the lymphocyte population was measured compared with the corresponding WT group. After CLP, a significant increase in the percentage cell count of NK cells was recorded in WT mice. Overall, following DHEA application in WT mice, an alteration in the cellular immune response was characterized by a reduction in the percentage counts of CD4(+), CD8(+) and NK cells. In the group of TNF-RI(-/-) mice treated with DHEA, no increase in the percentage cell count of NK cells was observed after CLP. No data for cell analysis were available from the CLP-TNF-RI(-/-) mice treated with saline, due to the high mortality rate in these animals. DHEA reduces the complications of sepsis in a TNF-RI-independent manner. Our study suggests that NK cells are involved in the protective mechanism of DHEA in WT mice. It would therefore seem that DHEA represents a feasible alternative therapy for the dysregulated immune system in sepsis.

Molecular methods to distinguish reactive and neoplastic lymphocyte expansions and their importance in transitional neoplastic states

Although lymphoma and leukemia usually can be diagnosed by routine cytology and histology, some cases present a diagnostic challenge for pathologists and clinicians. Often the dilemma lies in determining whether a population of lymphocytes is reactive or neoplastic. We review currently available methods for analyzing lymphocyte populations by immunophenotyping and by identifying clonally rearranged immunoglobulin and T-cell receptor genes and discuss how these tests can be used to clarify such diagnostic dilemmas. We also describe the detection of chromosomal abnormalities and methods on the horizon, such as gene expression profiling, to identify diagnostically useful oncogenes. Finally, we review the emerging concept of transitional neoplastic states, in which reactive lymphocytes transform to neoplastic lymphocytes in the presence of continued antigenic stimulation, such as that caused by infection with Helicobacter pylori. The existence of transitional neoplastic states underscores the need for an array of molecular diagnostic tools that would improve our ability to characterize lymphocyte populations in human and animal patients and enhance early detection of neoplastic lymphocytes such that eradication of the infectious or inflammatory stimulus could lead to cure.

Primary malignant melanoma of the oesophagus: a clinical and pathological study with emphasis on the immunophenotype of the tumours for melanocyte differentiation markers and cancer/testis antigens

SUMMARY

Primary malignant melanomas of the oesophageal squamous mucosa are exceedingly rare. We present here the clinical and pathological findings of 10 patients (mean age 64 years) with primary oesophageal melanoma, with emphasis on the immunophenotype of the tumours. The majority of melanomas were located in the mid to distal oesophagus and were large (mean tumour size at the time of diagnosis 6.2 cm; mean depth of invasion 1.86 cm). All but two of the melanomas were associated with an extensive in situ component. Half of the tumours were amelanotic. The histological spectrum was wide, including appearances mimicking lymphoma, poorly differentiated adenocarcinoma or sarcoma. Immunohistochemical studies were performed on six tumours using monoclonal antibodies (MAb) to S100 protein, tyrosinase (MAb T311), Melan-A (MAb A103), and gp100 (MAb HMB-45), as well as antibodies to five cancer/testis (CT) antigens (MAb CT7-33 to CT7/MAGE-C1, MAb ESO121 to NY-ESO-1, MAb 57B to MAGE-A4, MAb MA454 to MAGE-A1, and MAb M3H67 to MAGE-A3). Seven patients had metastatic disease at the time of presentation. All but one patient underwent resection of the tumour with negative surgical margins. Survival was poor, with a mean survival of 19.8 months. One patient, however, whose tumour was limited to the submucosa, is still alive 108 months post-oesophagectomy. All six melanomas examined by immunohistochemistry were positive for all the melanocyte differentiation markers tested. In addition, they were all positive for CT antigens, with MA454 being the most commonly found, suggesting that CT antigens may be a promising immunotherapeutic target for oesophageal melanomas.

Systematic Comparison of Dendritic Cell-based Immunotherapeutic Strategies for Malignant Gliomas: In Vitro Induction of Cytolytic and Natural Killer-like T Cells

OBJECTIVE

To compare the efficacy of various immunotherapeutic strategies of loading dendritic cells (DCs) with whole-glioma cell antigens and characterize the effector responses induced.

METHODS

DCs were either fused with major histocompatibility complex (MHC)-matched glioma cells (Fusion) or pulsed with apoptotic tumor cells (DC/Apo), total tumor ribonucleic acid (RNA) (DC/RNA), or tumor lysate (DC/Lys). These tumor-DC preparations were then assessed for their phenotype, cytokine profile, and capacity to stimulate autologous peripheral blood mononuclear cells (PBMCs) in vitro. Phenotype and tumor-specific cytolytic activities of various effector cell populations were characterized and compared.

RESULTS

The various tumor-DC preparations exhibited similar phenotype and cytokine profiles irrespective of the method of loading tumor-cell antigens. However, the fusion, DC/Apo, and DC/RNA induced superior tumor cytolytic activities in PBMCs compared with DC/Lys or DC and tumor controls. DC/Apo induced the greatest expansion of tumor-specific lymphocytes, as detected by trypan blue exclusion and thymidine incorporation assays. Flow cytometric analyses also revealed the highest relative percentages of T helper cells (CD3+CD4+), cytotoxic T lymphocytes (CTLs) (CD3+CD8+), and natural killer (NK)-like T cells (CD3+CD56+) in the DC/Apo group among all the groups studied, indicating that DC/Apo induced expansion of PBMCs bearing multiple T and NK cell markers. Interestingly, isolated NK-like T cells demonstrated significantly higher tumor cytotoxicity compared with CTLs isolated from the same groups and was also non-MHC-restricted.

CONCLUSION

Apoptotic tumor cells may be an optimal source of whole-tumor-cell antigen for immunotherapy of gliomas. The study also demonstrates for the first time that both CTLs and NK-like T cells are expanded and stimulated by mature, tumor-pulsed DCs.

Unusual immunophenotype of CD8+ T cells in familial hemophagocytic lymphohistiocytosis

Familial hemophagocytic lymphohistiocytosis (FHL) is an inherited, fatal disorder of infancy. We report here a 17-day-old female infant who presented with high fever, hepatosplenomegaly, hypertriglyceridemia, hypofibrinogenemia, thrombocytopenia, and liver failure. Leukocytosis was detected with circulating “atypical” lymphoid cells. Flow cytometric studies revealed expanded subpopulations of CD8+ T cells with unusual immunophenotypic features, including a subset that lacked CD5 expression. A liver biopsy showed hemophagocytic lymphohistiocytosis with exuberant infiltrates of CD8+ T cells that lacked perforin. Mutational studies revealed a 666C→A (H222Q) missense mutation in the perforin gene. T-cell receptor studies on flow-sorted T-cell subpopulations revealed no evidence of monoclonality. Analysis of T-cell receptor excision circle levels indicated long proliferative history in the aberrant CD8+ T-cell subsets. This case provides an instructive example of uncontrolled reactive proliferation of CD8+ T cells in FHL, resulting in atypical morphology and unusual immunophenotypic features that might suggest malignancy in other clinical settings.

Correlation between karyotype and quantitative immunophenotype in acute myelogenous leukemia with t(8;21)

Acute myelogenous leukemia with t(8;21) is a distinct clinicopathologic entity in which the malignant myeloblasts display a characteristic pattern of surface antigen expression. Quantitative analysis of surface marker expression in patients with this chromosomal abnormality compared to acute myelogenous leukemia patients with a different karyotype has not been reported. From 305 consecutive newly diagnosed acute myelogenous leukemia patients underwent immunophenotyping and cytogenetic analysis at our center; 16 patients (5.2%) had a t(8;21). Fluorescence intensity values were obtained, using a set of reference microbeads, by conversion of mean channel fluorescence to molecular equivalent of soluble fluorochrome. Patients with t(8;21) displayed higher levels of CD34, HLA-DR and MPO expression (P < 0.001 for each) and lower levels of CD13 (P = 0.03) and CD33 (P = 0.02) expression. In order to study the sensitivity, specificity and predictive value of these markers, molecular equivalent of soluble fluorochrome thresholds were statistically determined. The statistically established threshold for each of the individual markers (CD34 > 60.5 x 10(3), HLA-DR > 176.1 x 10(3), MPO > 735.1 x 10(3), CD13 < 24.3 x 10(3) and CD33 < 17.3 x 10(3)) had a sensitivity of 100%, a specificity of 62-92% and a positive predictive value of 7-45%. In multivariate analysis, two quantitative patterns (CD34 > 60.5 x 10(3) and MPO > 176.1 x 10(3); CD33 < 17.3 x 10(3) and MPO > 176.1 x 10(3)) had a sensitivity, specificity and positive predictive value of 100%. These aberrant phenotypic patterns might help identify patients with t(8;21) at diagnosis and could be useful in minimal residual disease monitoring.

Quantitative histology by multicolor slide-based cytometry

BACKGROUND

In lymphatic organs, the quantitative analysis of the spatial distribution of leukocytes by tissue cytometry would give relevant information about altercations during diseases (leukemia, HIV, AIDS) and their therapeutic regime, as well as in experimental settings.

METHODS

We have developed a semiautomated analysis method for laser scanning cytometry (LSC) termed "multiple thresholding," which is suitable for archived or fresh biopsy material of human lymph nodes and tonsils. Sections are stained with PI for nuclear DNA and up to four antigens using direct and indirect immunofluorescence (argon laser, Ar) or on specific cell labeling. Due to the heterogeneity of cell density, measurements are performed repeatedly at different threshold levels (low threshold: regions of low cellular density, germinal center; high threshold: dense regions, mantle zone). Data are acquired by single-(Ar) or dual-laser excitation (Ar-HeNe) in order to analyze single-(FITC) up to fourcolor (FITC/PE/PECy5/APC) stained specimen.

RESULTS

Percentage and cellular density of cell-subsets is quantified in different microanatomical regions of the specimen. These data were highly correlated with manual scoring a identical specimens (r(2) = 0.96, P < 0.0001). With LSC, semiautomated operator-independent immunophenotyping in tissue sections of lymphatic organs with up to three antibodies simultaneously is possible.

CONCLUSIONS

We expect this tissue cytometric approach to yield new insight into processes during diseases and help to quantify the success of therapeutic interventions.

Immunophenotyping of the cutaneous cellular infiltrate after atopy patch testing in cats with atopic dermatitis

Cats with spontaneously occurring atopic dermatitis have clinical and immunocytochemical characteristics compatible with these in humans with atopic dermatitis (AD). The atopy patch test (APT) has proven to be a valuable tool in elucidating the disease process in humans. Additionally, the APT is very specific and bypasses the problem of conflicting results due to differences in chronicity of lesions of AD patients. We adapted the APT for use in cats to explore the suitability of the APT as a tool to study the onset of allergic inflammation in cats with atopic dermatitis. APT were performed in AD cats (n = 6) and healthy cats (n = 10). All cats were patch tested with two allergens in three different dilutions and a diluent control. The allergens for the APT were selected from positive intradermal test and /or prick test results and consisted of: Dermatophagoides farinae, D. pteronyssinus, Tyrophagus putrescentiae, and a grass pollen mixture. APT were read after 10, 24 and 48 h, and punch biopsies for immunohistochemical evaluation were collected at these time points. Macroscopically positive APT reactions were observed in three out of six cats at 24 and/or 48 h with allergen concentrations of 25,000 and 100,000 NU/ml. Reactions were not observed at negative control sites and neither in control animals. A significantly increased number of IL-4+, CD4+, CD3+, MHC class II+ and CD1a+ cells was found in one AD cat with positive APT reactions. Five out of six AD cats had significantly increased IL-4+ T cell numbers at 24 and/or 48 h. Our data indicate that in cats, macroscopically positive patch test reactions can be induced, which have a cellular infiltrate similar to that in lesional skin. We found a high specificity and a macroscopically positive APT reaction in half of the cats, which is similar to what is seen in humans. Hence, the APT in cats might be a useful tool in studying the immunopathogenesis of feline atopic dermatitis.

Chronic mucocutaneous candidiasis and primary hypothyroidism in two families

We describe the clinical and immunological features of two families with chronic mucocutaneous candidiasis (CMC) and primary hypothyroidism. Family A includes three siblings with both candidiasis and hypothyroidism and four individuals with hypothyroidism only. Family B includes four members with candidiasis, of whom one (a male child) also had hypothyroidism. All individuals affected with CMC had suffered from oral candidiasis and onychomycosis since infancy. Facial seborrhoic dermatitis, general folliculitis and scaling blepharitis were main manifestations. Hypothyroidism became evident during childhood. No thyroid antibodies were present in the affected siblings in family A, while the male in family B with hypothyroidism had antibodies against thyroid peroxidase at diagnosis. Immunological evaluation revealed intra-individual variations in serum immunoglobulin levels, lymphocyte subsets and proliferative responses, but there were no consistent abnormalities. Vaccine responses were normal. AIRE gene region microsatellite markers did not segregate with disease nor were autoantibodies typical for autoimmune polyendocrine syndrome type 1 detected in the families.

CONCLUSION

The link between hypothyroidism and chronic mucocutaneous candidiasis remains to be identified.

[Immunophenotyping of haematologic malignancies]

Over the last 10 years, immunophenotyping of haematologic malignancies has become an indispensable diagnostic supplement to the classical morphological approach. Immunophenotyping of haematopoietic cells is performed with the use of a number of monoclonal antibodies (MOABs), which are directed specifically against structures of blood cells that become expressed at the different stages of differentiation and maturation. Cells to which the fluorescently labelled MOABs are directed can be recognised and measured using fluorescence microscopy or fluorescence flow cytometry. Many MOABs, fluorochromes and user-friendly flow cytometers have become available in the last 15 years, as a result of which immunophenotyping is now routinely applied in clinical practice. Immunophenotyping has the potential to classify leukaemias and other malignant lymphomas according to cell type and stage of maturation. This information is important for the establishment of the right diagnosis and prognosis, and for the optimal treatment choice. In a number of cases immunophenotyping provides information which cannot be obtained by simple morphological investigation. The immunophenotyping of blood and bone-marrow cells is also a sensitive method for detecting minimal residual disease after an apparent complete remission has been achieved.

Flow cytometry for diagnosis and assessment of prognosis in patients with myelodysplastic syndromes

The Myelodysplastic Syndrome (MDS) comprises a spectrum of hematopoietic stem cell disorders. Identification of additional parameters that might distinguish different risk groups or entities would be useful. Flow cytometric studies have begun to characterize individual or composite immunophenotypic abnormalities as well as light scatter properties that may be helpful for diagnosis and of prognostic value for the natural course of the disease and for outcome after therapy. Here we review the current state of the art of the use of flow cytometry in patients with MDS.