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PubMed2004

Vpr and Vpu are important for efficient human immunodeficiency virus type 1 replication and CD4+ T-cell depletion in human lymphoid tissue ex vivo.

The relevance of the accessory vpr, vpu, and nef genes for human immunodeficiency virus type 1 (HIV-1) replication in human lymphoid tissue (HLT), the major site of viral replication in vivo, is largely unknown. Here, we show that an individual deletion of nef, vpr, or vpu significantly decreases HIV-1 replication and prevents CD4+ T-cell depletion in ex vivo HLT. However, only combined defects in all three accessory genes entirely disrupt the replicative capacity of HIV-1. Our results demonstrate that nef, vpr, and vpu are all essential for efficient viral spread in HLT, suggesting an important role in AIDS pathogenesis.

CD4-Positive T-Lymphocytes↗

PubMed1998

T-Helper 1 and T-helper 2 cytokine responses in gut-associated lymphoid tissue following enteric reovirus infection.

Enteric infection of mice with reovirus serotype 1 elicits antibody and cytotoxic T-lymphocytes in gut-associated lymphoid tissue (GALT). This led to the hypothesis that T-helper 1 (Th1) and T-helper 2 (Th2) responses develop in GALT. Reverse transcriptase-polymerase chain reactions on RNA from Peyer's patches (PP), intraepithelial lymphocytes (IEL), and lamina propria (LP) lymphocytes demonstrated that interferon (IFN)-gamma message was increased in PP and IEL, but not in LP following infection. No increase in mRNA for interleukin (IL)-4, IL-5, or IL-6 was detected. IFN-gamma, IL-5, and IL-6 were produced in in vitro cultures of PP 4-10 days postinfection. PP and spleen lymphocytes from infected mice produced IFN-gamma, but no IL-5 following in vitro restimulation. Infection also induced production of mRNA for the beta2 chain of the IL-12 receptor in PP. We conclude that reovirus induces robust Th1 and weak Th2 cell responses in GALT.

Animals↗

PubMed1996

[Countermeasures for hypofunction of gut associated lymphoid tissue during TPN in rats].

Total parenteral nutrition (TPN) causes atrophy of the intestinal mucosa, resulting in the degeneration and atrophy of gut associated lymphoid tissues (GALT). This suppressive effect of TPN on GALT was examined using rats. In rats receiving TPN for 2 weeks, a decrease and atrophy of Peyer's patches and a decrease in thoracic duct lymphocytes (TDL) were observed. Daily oral administration of 1000 mg/kg PSK to the rat in the TPN group corrected the number and size of Peyer's patches, and the number of TDL and its subsets were also improved compared with the TPN group. Diminution of the S-IgA of bile and portal venous blood was noticed during TPN in rats. But the groups PSK administrated were increased the amount of S-IgA in bile and portal venous blood. The immune plasma cells in the Peyer's patches were observed, the number of the MHC-class II, T helper, and IL-2 (T CGF) positive cells were decreased in the TPN group compared with control group (PSK group). It has been concluded, therefore, that PSK is effective for improving GALT inhibition caused by TPN.

Animals↗

PubMed2006

Toll-like receptor 2 and 9 are expressed and functional in gut-associated lymphoid tissues of presuckling newborn swine.

To clarify the crucial role of Toll-like receptor (TLR) 2 and TLR9 in immature gut-associated lymphoid tissues (GALT), we focused on the expression of TLR2 and TLR9 and the immune responses induced by their ligands in the GALT of presuckling newborn swine. Quantitative real-time PCR revealed that TLR2 and TLR9 mRNA were expressed at detectable levels in all tested tissues (heart, thymus, lung, spleen, liver, kidney, skeletal muscle, duodenum, jejunum, ileum, ileal Peyer patches (Pps), and mesenteric lymph nodes (MLN)). In particular, in immature intestinal tissues and GALT, TLR2 and TLR9 mRNA were expressed at higher levels in ileal Pps and MLN than in the duodenum, jejunum, and ileum. We confirmed that the TLR2 and TLR9 proteins were also highly expressed and that their ligands were preferentially recognized by TLR2- or TLR9-expressing cells in the MLN and ileal Pps. Zymosan, CpG2006, and lactic acid bacteria could promote mitogenesis and production of multiple cytokines by the MLN and ileal Pps. In addition, double immunostaining for cytokeratin 18 and either TLR2 or TLR9 revealed that both TLR2 and TLR9 are strongly expressed in the columnar membranous (M) cells. Interestingly, while the apical membrane of the columnar M cells strongly expressed TLR2 protein and preferentially recognized zymosan, both "TLR2 expression on the apical membrane" and "TLR2-mediated zymosan binding" were negligible in neighboring enterocytes. These results indicate that TLR2 and TLR9 allow MLN and ileal Pps to respond to a variety of bacterial components immediately after birth, thereby providing newborns with a host defense system.

Animals↗

PubMed2006

The incidence and anatomic site specificity of chromosomal translocations in primary extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) in North America.

Several balanced translocations have been identified in extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) but there are few data regarding their frequency in different anatomic sites or the frequency of translocations involving BCL6 or kappa or lambda immunoglobulin light chain genes (IGK or IGL), particularly in patients from geographic regions other than Europe and Japan. One hundred thirty-three paraffin-embedded North American primary MALT lymphoma specimens from diverse anatomic sites were studied by fluorescence in situ hybridization (FISH) using probes for API2-MALT1, IGH-MALT1, IGH-BCL10, IGH-FOXP1, IGH, +/- centromeres 3, 7, 12, and 18, and a subset (n=74) were analyzed using FISH probes for IGK, IGL, and BCL6. Translocations were mutually exclusive and were detected in 26% of cases (17% API2-MALT1, 5% IGH-MALT1, 3% IGH-unknown translocation partner, and 1% IGH-BCL10). Aneuploidy was associated with IGH-MALT1 and IGH-BCL10 but only rarely with API2-MALT1. There was striking site specificity, with API2-MALT1 showing a marked predilection for lung and intestine, and IGH-MALT1 and IGH-BCL10 occurring almost exclusively in lung. Twenty-three percent of translocation-negative primary MALT lymphomas from diverse sites showed complete/partial trisomy 18. No MALT lymphomas with translocations involving IGK, IGL, BCL6, or FOXP1 were identified. This FISH panel detected cytogenetic abnormalities in half of all MALT lymphomas, and translocations arose preferentially in MALT lymphomas of the lung and gastrointestinal tract. Differences in incidence and anatomic site specificity of translocations between North American and non-North American cases may reflect geographic variability of infectious or other etiologic factors.

Adaptor Proteins, Signal Transducing↗

PubMed2004

Expression of COX-2, iNOS, p53 and Ki-67 in gastric mucosa-associated lymphoid tissue lymphoma.

AIM: To assess the expression of cyclooxygenase-2 (COX-2), nitric oxide synthase (iNOS), p53 and Ki-67 in gastric mucosa-associated lymphoid tissue (MALT) lymphoma and clarify the relationship between COX-2 expression and iNOS or p53 expression in these patients. METHODS: The expressions of COX-2, iNOS, p53 and Ki-67 were detected in 32 gastric MALT lymphoma specimens and 10 adjacent mucosal specimens by immunohistochemical Envision method. RESULTS: COX-2 and iNOS expressions were significantly higher in gastric MALT lymphoma tissues than those in adjacent normal tissues. The expression of COX-2 was observed in 22 of 32 cases of MALT lymphoma tissues (68.8%). A positive cytoplasmic immunoreactivity for iNOS was detected in 17 of 31 cases (53.1%). COX-2 expression in gastric MALT lymphoma tissues was positively correlated with iNOS expression (r=0.448, P=0.010) and cell proliferative activity analyzed by Ki-67 labeling index (r=0.410, P=0.020). The expression of COX-2 protein did not correlate with age, sex, stage of disease, lymph node metastasis or differentiation. The accumulation of p53 nuclear phosphoprotein was detected in 19(59.4%) of tumors. p53 protein was expressed in 11 of 23 assessed LG tumors and in 8 of 9 assessed HG tumors. The difference of p53 positivity was found statistically significant between LG and HG cases (P=0.0302). The p53 accumulation correlated with advanced clinical stage (stage III+IV vs stage I+II, P=0.017). There was a significant positive correlation between COX-2 expression and p53 accumulation status (r=0.403, P=0.022). The mean PI of Ki-67 in each grade group were 36.0+/-7.73% in HG and 27.4+/-9.21% in LG. High-proliferation rate correlated with HG tumors (r=0.419, P=0.017). The correlation coefficient showed a significant positive correlation between PI and COX-2 expression in MALT lymphoma patients (r=0.410, P=0.020). CONCLUSION: COX-2 expresses in the majority of gastric MALT lymphoma tissues and correlates with cellular proliferation and iNOS expression. COX-2 overexpression is closely associated with p53 accumulation status. iNOS and COX-2 may play a synergistic role in the pathogenesis of gastric MALT lymphoma.

Biomarkers, Tumor↗

PubMed1992

Low-grade gastric B-cell lymphoma of mucosa-associated lymphoid tissue (MALT): a multifocal disease.

Gastrectomy specimens from five patients following gastroscopic biopsies which showed low-grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) were examined by serially sectioning and paraffin wax embedding using a 'swiss roll' technique. This procedure allowed the construction of a map of the specimen on which the distribution of the lymphoma could be plotted. In each case confluent lymphoma was identified. In addition small foci of lymphoma consisting of 1-4 lymphoid follicles surrounded by neoplastic centrocyte-like cells were seen. The positions of these 'micro-lymphomas' were plotted on the gastrectomy maps, showing multiple foci distributed throughout the gastric mucosa. The identification of these microscopic lesions may explain the development of local relapse, often after a long disease-free interval, in patients with gastric MALT lymphoma treated by partial gastrectomy where excision appears to have been complete. Patients treated in this way should, therefore, be followed-up indefinitely, with regular endoscopy and gastric biopsy, in order to identify early local disease relapse.

Adult↗

PubMed1994

Nasopharyngeal lymphoid tissue masses in patients with human immunodeficiency virus-1. Histologic findings and clinical correlation.

BACKGROUND: Although the histologic changes in lymph nodes in patients infected with the human immunodeficiency virus-1 (HIV-1) are well described, the histology and resulting clinical symptoms of hyperplastic nasopharyngeal lymphoid tissue (NPLT) in these patients are not widely known, particularly to pathologists and oncologists. METHODS: Nine patients with HIV-1 presented with a nasopharyngeal mass, nasal stuffiness, nasal bleeding, hearing loss, and cervical lymphadenopathy in various combinations. Tonsillar tissue was biopsied or removed from all nine. RESULTS: The tonsillar tissue showed a spectrum of the changes of reactive lymphoid hyperplasia. CONCLUSIONS: Clinicians and pathologists must be aware of the spectrum of histologic changes and clinical features relating to biopsies from NPLT to interpret the changes correctly and to avoid a misdiagnosis of malignant lymphoma.

Adult↗

PubMed1994

Statin--a novel marker of nonproliferation. Expression in nonneoplastic lymphoid tissues and follicular lymphomas.

Statin is a 57 kDa nuclear protein exclusively found in noncycling cells. Its expression in hematolymphoid cells had not been examined previously. The authors studied statin immunoreactivity in nonneoplastic lymphoid tissues from 26 lymph nodes, 3 tonsils, and 2 spleens. Statin was detected primarily in small lymphoid cells and histiocytes, along with such accessory elements as fibroblasts and endothelial cells. The distribution of positive cells showed an inverse correlation with the proliferative activity of the various lymphoid compartments. Statin labeling was also quantified in 15 follicular lymphomas and compared with that in hyperplastic follicles. Although reactivity in benign germinal centers was less than that in neoplastic follicles, this difference did not prove statistically significant. Statin provides an alternative to proliferation-associated parameters, such as Ki-67 and proliferating cell nuclear antigen, in the analysis of hematolymphoid processes and may be helpful in the dissection of their kinetic heterogeneity.

Cell Cycle Proteins↗

PubMed1991

Differences in murine gut-associated lymphoid tissues in generating broadly nonspecific cytotoxic cells in response to interferon alpha A/D and interleukin 2.

We examined the response of cells of murine gut-associated lymphoid tissues to agents that augment the activity of natural killer (NK) cells. Specifically, we studied the effect of polyinosinic: polycytidylic acid (Poly I:C) in vivo, and recombinant interferon alpha A/D (rIFN alpha A/D) and recombinant interleukin 2 (rIL2) in vitro on lymphoid cells of mesenteric lymph nodes (MLN) and Peyer's patches (PP) in generating cytotoxicity against NK-sensitive (YAC-1) and NK-insensitive (B16BL6) tumor targets. The effect of these agents on spleen cells was examined for comparison with their effect on MLN and PP cells and as a positive control. MLN and PP cells lacked spontaneous NK activity: however, NK activity could be augmented to different levels by the three agents. The treatment of mice in vivo with Poly I:C induced considerable cytotoxicity in the spleen and MLN but only a weak cytotoxic response in PP. The in vitro enhancement of NK activity by rIFN alpha A/D was strong in the spleen, intermediate in MLN, and consistently poor in PP. The weak NK augmentation by rIFN alpha A/D in PP was not restricted to a single mouse strain. PP cells from five strains of mice responded poorly to rIFN alpha A/D. Furthermore, NK augmentation by rIFN alpha A/D in PP cells did not improve after passing the responder cells through nylon wool, indicating that the lack of augmentation of NK activity was not the result of a preponderance of B cells or the masking of NK cells by adherent lymphoid populations in PP. In contrast to weak augmentation of NK activity by rIFN alpha A/D, considerable IL2-induced lymphocyte-activated killer (LAK) activity against NK-insensitive B16BL6 tumor cells was induced in PP. Limiting-dilution analysis showed that the frequency of LAK precursors in the MLN and PP was not markedly different from that of the spleen. The differences among spleen, MLN, and PP lymphoid populations in generating the broadly nonspecific cytotoxic effector cells in response to rIFN alpha A/D or rIL2 may result from differences in the pools of different pre-NK cells or to differential sensitivity of the same pool of pre-NK cells to rIFN alpha A/D and rIL2 in different anatomical locations.

Animals↗

PubMed2004

Chemokine receptors that mediate B cell homing to secondary lymphoid tissues are highly expressed in B cell chronic lymphocytic leukemia and non-Hodgkin lymphomas with widespread nodular dissemination.

B cell neoplasms present heterogeneous patterns of lymphoid organ involvement, which may be a result of the differential expression of chemokine receptors. We found that chemokine receptor (CCR)7, CXC chemokine receptor (CXCR)4, or CXCR5, the main chemokine receptors that mediate B cell entry into secondary lymphoid tissues and their homing to T cell and B cell zones therein, were highly expressed in B malignancies with widespread involvement of lymph nodes. Conversely, those pathologies with little or no nodular dissemination showed no expression to very low levels of CCR7 and CXCR5 and low to moderate levels of CXCR4. These findings provide evidence for the role of CCR7, CXCR4, and CXCR5 in determining the pattern of lymphoid organ involvement of B tumors. Functional studies were performed on B malignancies expressing different levels of CCR7, CXCR5, and CXCR4. Multiple myeloma (MM) cells did not express CCR7 nor CXCR5 and did not migrate in response to their ligands; a moderate expression of CXCR4 on MM cells was accompanied by a migratory response to its ligand, CXCL12. By contrast, cells from B cell chronic lymphocytic leukemia (B-CLL) expressed the highest levels of these chemokine receptors and efficiently migrated in response to all ligands of CCR7, CXCR4, and CXCR5. In addition, the migration index of B-CLL cells in response to both of the CCR7 ligands correlated with the presence of clinical lymphadenopathy, thus indicating that the high expression of functional chemokine receptors justifies the widespread character of B-CLL, representing a clinical target for the control of tumor cell dissemination.

ADP-ribosyl Cyclase↗

PubMed1989

Application of the AgNOR method to cell imprints of lymphoid tissue.

The argyrophil (AgNOR) staining technique for nucleolar organizer regions was applied to both cell imprint preparations and 3 microns sections of 40 specimens of lymphoid tissue (10 normal tonsil, 10 reactive follicular hyperplasia, and 10 low-grade and 10 high-grade non-Hodgkin's lymphomas). The mean AgNOR count per nucleus was higher for imprint preparations than for 3 microns sections for each group of specimens (P less than 0.01). The difference was particularly evident for specimens with high AgNOR counts, that is, the high-grade non-Hodgkin's lymphomas (pooled mean AgNOR count/cell 16.3 for imprints as opposed to 6.0 for 3 microns sections, P less than 0.0001). Furthermore, individual AgNOR dots were much more readily discerned in cell imprints than in sections, and this appears to be the method of choice if pathologists wish to at least approach absolute rather than relative AgNOR counts.

Humans↗

PubMed1989

Pathologic findings in adenosine deaminase deficient-severe combined immunodeficiency. II. Thymus, spleen, lymph node, and gastrointestinal tract lymphoid tissue alterations.

Eight autopsies of patients with adenosine deaminase deficient-severe combined immunodeficiency disease (ADA-SCID) were reviewed with special emphasis on the lymphoid tissues. The thymus histology in five cases was remarkably uniform, whether or not prior ADA enzyme replacement or immunologic reconstitution therapy had been administered. Lymph nodes and spleens in all cases examined showed a residual nonlymphoid architectural framework corresponding to usual T and B cell zones found in normals. The development of an extranodal, monoclonal IgA lambda B cell immunoblastic lymphoma as a terminal event in one patient after several years of successful ADA enzyme replacement therapy through multiple red blood cell transfusions is described. In another patient with long-term ADA enzyme replacement, a terminal autoimmune hemolytic anemia developed. Autopsy revealed severe deposits of iron in the B cell zones of the lymph nodes, which is an unusual location. In addition, iron deposits outlined the splenic trabeculae, as well as the ring fibers and bridging fibers of the splenic sinuses.

Adenosine Deaminase↗

PubMed2002

Treatment of extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue type with cladribine: a phase II study.

PURPOSE: As chemotherapy has not been extensively studied in patients with lymphoma of the mucosa-associated lymphoid tissue (MALT), we initiated a prospective study to evaluate the activity of the nucleoside analog cladribine (2-chlorodeoxyadenosine [2-CdA]) in this disease. PATIENTS AND METHODS: Patients with histologically verified MALT-type lymphoma were enrolled. 2-CdA was administered at a dose of 0.12 mg/kg body weight on 5 consecutive days, as a 2-hour infusion. Cycles were repeated every 4 weeks for a maximum of six cycles. RESULTS: Nineteen patients with gastric and seven patients with extragastric MALT lymphoma were enrolled. All patients were chemotherapy-naive, and two had been locally irradiated before systemic relapse of the lymphoma. A total of 102 cycles was administered to our patients (median number of cycles per patient, four). All 25 assessable patients responded to treatment: 21 patients (84%) achieved complete remission (CR) and four patients achieved partial remission. All patients (100%) with gastric presentation, but only three patients (43%) with extragastric presentation, achieved CR. Toxicities were moderate and mainly hematologic and required dose reduction and/or premature discontinuation of therapy in only three cases. Two patients died from vascular events, one shortly after the first cycle because of myocardial infarction and the other from stroke 3 months after the second course. Three patients relapsed after 13, 18, and 22 months and one patient showed progressive disease after 15 months. At present, 24 patients are alive at a median follow-up time of 32 months. CONCLUSION: Our data demonstrate that 2-CdA is highly effective in inducing CR in 84% of patients with MALT-type lymphoma.

Adult↗

PubMed1997

Recovery of gut-associated lymphoid tissue and upper respiratory tract immunity after parenteral nutrition.

OBJECTIVE: The authors characterize the recovery of parenteral nutrition-induced changes in gut-associated lymphoid tissue (GALT) and upper respiratory tract immunity with enteral nutrition and provide further information defining the effects of enteral feeding on mucosal immunity. SUMMARY BACKGROUND DATA: The small intestine plays a prominent role in development and maintenance of mucosal immunity, both intestinal and extraintestinal, primarily through immunoglobulin A (IgA)-mediated mechanisms. Prior research has shown that mice fed total parenteral nutrition (TPN) have reduced GALT T and B cells, the cells responsible for IgA production, as well as impaired upper respiratory tract immunity to viral challenge of previously immunized animals. The recovery of TPN-induced changes in GALT and upper respiratory tract immunity after enteral refeeding is studied. METHODS: Male institute of Cancer Research mice received 5 days of TPN followed by 0 to 4 days of chow. Small intestinal GALT was characterized by flow cytometry. In a second experiment, animals were immunized intranasally with moused-adapted influenza virus. Three weeks later, one group received a 5-day course of TPN followed by enteral refeeding for 5 days. A second group received TPN alone. Both groups were challenged with intranasal virus and killed 40 hours postchallenge to determine viral shedding from the upper respiratory tract. RESULTS: Animals fed TPN only had significantly fewer GALT lymphocytes compared with those chow-fed control subjects. Peyer's patch counts increased after a single day of refeeding, returning to normal levels by 48 hours. Lamina propria counts remained significantly depressed after 24 hours of refeeding, but also returned to normal after 48 hours of refeeding. The T-cell and B-cell populations mimicked total cell patterns. Lamina propria CD4+/CD8+ ratio returned to normal only after 72 hours of refeeding. None of the 9 animals refed enterally for 5 days were positive for viral shedding, compared with 8 of 12 matched TPN-fed animals. CONCLUSIONS: Enteral refeeding after TPN is associated with rapid repletion of GALT cellularity, initially within Peyer's patches and subsequently within the lamina propria. Refeeding corrects the impairment of IgA-mediated upper respiratory tract antiviral immunity occurring with TPN administration. This work further enhances the authors' knowledge of the underlying immunologic differences influenced by routes of nutrition.

Animals↗

PubMed2002

A light and electron microscopic quantitative analysis of nerve-immune cell contacts in the gut-associated lymphoid tissue of the mouse colon.

Light microscopy (LM) histochemistry and transmission electron microscopy (EM) have been used to investigate the structural relationship between immunocompetent cells and enteric nerves in the gut-associated lymphoid tissue (GALT) of the mouse colon, i.e., a) the scattered immune cells in the lamina propria, b) the lymphoid follicles and c) the cryptopatches. Nerve-immune cell contacts have been quantified by LM, using the osmium-zinc iodide procedure for visualizing nerve fibers. Appositions of nerves to immune cells have been studied by EM when the distance between the immune cell plasma membrane and the neurilemma was 200 nm or less. In the diffuse GALT a), the LM incidence of nerve-lymph cell and nerve-plasma cell contacts has been calculated to be one and half and, respectively, three times greater than would be expected by chance alone (P < 0.0001 in both cases). EM showed close apposition of axonal varicosities, mostly containing 60 nm diameter dense-cored vesicles, to B lymphoblasts/immunoblasts or plasma cells. In isolated lymphoid follicles b), nerve-immune cell contacts were identified almost exclusively in the T-cell dependent parafollicular regions; the incidence of such contacts, calculated by LM, did not exceed expected theoretical values. By EM, apposition of nerve varicosities to small/middle-sized lymphocytes containing cytoplasmic lysosomal granules was seen sporadically. Examination of nerve-immune cell contacts in cryptopatches c), a recently identified extrathymic T-cell generating compartment, allowed recognition of a small proportion of nerve-lymph cell structural interactions, both at LM and EM. This study provides systematic quantitative data on the microanatomical relationship between enteric nerves and immune cells in the various GALT compartments. Findings suggest that such nerve-immune cell contacts might represent the structural foundation for communication between enteric nerves and the GALT.

Animals↗

PubMed1982

Gut and bronchus associated lymphoid tissue: an overview.

The mucosal lymphoid aggregates in lung and gut contain precursor cells destined to seed mucosal tissues with IgA containing cells. It is likely that both tissues also are sources of both IgE B cell precursors as well as the cells responsible for their regulation (38). Although the traffic of B cells is relatively well understood from the standpoint of IgA, the factors responsible for localization in mucosal tissue are at best unclear. Furthermore, little is known about the migration patterns of helper or suppressor cells of any kind and these may have, if derived from mucosal tissue, a preferential site of action in the mucosa. The mucosal mast cell may well be a cell of different lineage than the mast cell from the peritoneal cavity and may itself have a mucosal localization pattern. Much more work needs to be done to render some of these speculations onto a better factual base, and to harness these systems in provision of better approaches to vaccination and control of disease.

Animals↗

PubMed1982

Dipeptidyl(amino)peptidase IV (DAP-IV) histochemistry on normal and pathologic lymphoid tissues.

The enzyme glycyl-proline-naphthylamidase (dipeptidyl-amino-peptidase IV), (DAP-IV) has been histochemically analysed in normal and pathological specimens of different lymphoid tissues. In all the tissues examined, the enzyme appeared to be highly specific for T cells. Using chloroformacetone fixation and sections of proper thickness, DAP-IV could be successfully demonstrated in cortical thymocytes, which exhibited weak reactivity, as well as in medullary thymocytes which showed a more intense and variable reactivity. A similar reactivity was observed in T cells of peripheral blood, lymph node, and spleen. Various acute lymphoblastic and nonlymphoblastic leukemias and malignant lymphomas were studied using the histochemical method for DAP-IV. Malignant cells from all the acute leukemias and from the B-cell lymphomas were DAP-IV unreactive, while strong reactivity was observed in one case of T-CLL and one case of T-PLL. The possible relationship of DAP-IV positivity pattern with T-cell maturation and its potential use as a diagnostic tool in lymphoproliferative disorders are discussed.

Bone Marrow↗