Alpha 4 beta 7 integrin expression is associated with the leukemic evolution of human and murine T-cell lymphoblastic lymphomas.

We have previously shown that the in vivo coordinated expression of individual alpha 4 and beta 7 integrin chains correlated with the leukemic potential displayed by cell lines derived from murine lymphoblastic T-cell lymphomas (T-LBLs) when transplanted subcutaneously into syngeneic AKR mice. In the present study, by using immunofluorescence and immunocytochemical analyses, we have confirmed that the in vivo up-regulation of the alpha 4 beta 7 heterodimeric complex is associated with the leukemic behavior of AKR T-LBLs. In addition, when compared with the parental, highly leukemic NQ22 cells, the variant cell line NQ22V exhibited a reduced leukemic potential that was invariably associated with a delayed alpha 4 beta 7 up-regulation in vivo Moreover, the leukemic cell line SJ-1, derived from a spontaneous T-LBL of the SJL strain, also displayed high levels of alpha 4 beta 7 expression with a pattern of tissue distribution similar to that of NQ22 cells from leukemic AKR animals. Of note, in most of the tissues involved by murine T-LBL dissemination, and particularly in liver, kidney, and lung, alpha 4 beta 7-positive leukemic cells were always located around strongly VCAM-1-positive vascular spaces. These findings are consistent with a possible role of alpha 4 beta 7/VCAM-1 interactions in the extravasation and, consequently, in the leukemic dissemination of murine T-LBL cells. Immunocytochemical analysis carried out in 11 human T-LBLs showed that pathological lymph nodes from all 7 cases with bone marrow infiltration at presentation carried alpha 4 beta 7-positive cells, whereas all 4 aleukemic T-LBLs were repeatedly alpha 4 beta 7 negative, also in metachronous lesions. These findings suggest that alpha 4 beta 7-positive human T-LBLs may represent a distinct clinicopathological entity. In addition, alpha 4 beta 7 expression was significantly more prevalent in younger patients (< 11 years; P = 0.02), further supporting such a hypothesis. Moreover, as in murine T-LBLs, the pattern of alpha 4 beta 7 positivity in involved lymph nodes was mainly focal, whereas nearly all neoplastic cells infiltrating bone marrow expressed this integrin, suggesting a possible role for alpha 4 beta 7 in the leukemic dissemination also of human T-LBLs.

All-trans, 13-cis and 9-cis retinoic acids induce a fully reversible growth inhibition in HNSCC cell lines: implications for in vivo retinoic acid use.

Retinoids are a group of vitamin A analogues that have shown promise as chemopreventive and therapeutic agents in many types of malignancy and have been entered in clinical trials with some successful results. To better understand the mechanism that mediates retinoid action and the anti-proliferative effects, we treated 7 human oral squamous-cell carcinoma (SCC) cell lines (FADU, HEp-2, CCL-17, SCC-9, SCC-15, SCC-25 and HN-212) with 10(-6) M of all-trans retinoic acid (ATRA), 9-cis and 13-cis retinoic acid (RA) in continuous for different periods of time. We assessed the extent of growth inhibition, the stability of the anti-proliferative effect and the mRNA expression levels (by RT-PCR) of RA receptors (RARs), retinoid X receptors alpha (RXR alpha) and cytosolic RA-binding proteins (CRBP I and CRABP II) in treated cells compared with controls. The data obtained showed that all 3 RAs were able to inhibit the cellular growth of the tested cell lines, although to a different extent. The cis compounds were able to inhibit the proliferation of all cell lines, whereas ATRA was ineffective in inhibiting the proliferation of the CCL-17 cell line, which was naturally resistant to ATRA concentrations in the range between 10(-5) and 10(-6) M. All inhibitory effects were completely reversible since all cell lines restored their normal growth proliferation within few days after drug removal. RT-PCR analysis of the receptor and cell binding protein status of control and treated cells showed a good correlation between growth inhibition and induction of, or increase in, the expression levels of RAR beta in RA-treated cells. No differences were observed in RAR alpha and RXR alpha mRNA expression levels between control and treated cells. CRBP I, CRABP II and RAR gamma mRNA levels increased in some treated cell lines but not in all.

Retinoids irreversibly inhibit in vitro growth of Epstein-Barr virus-immortalized B lymphocytes.

Natural and synthetic retinoids have proved to be effective in the treatment and prevention of various human cancers. In the present study, we investigated the effect of retinoids on Epstein-Barr virus (EBV)-infected lymphoblastoid cell lines (LCLs), since these cells closely resemble those that give rise to EBV-related lymphoproliferative disorders in the immunosuppressed host. All six compounds tested inhibited LCL proliferation with no significant direct cytotoxicity, but 9-cis-retinoic acid (RA), 13-cis-RA, and all-trans-RA (ATRA) were markedly more efficacious than Ro40-8757, Ro13-6298, and etretinate. The antiproliferative action of the three most effective compounds was confirmed in a large panel of LCLs, thus appearing as a generalized phenomenon in these cells. LCL growth was irreversibly inhibited even after 2 days of treatment at drug concentrations corresponding to therapeutically achievable plasma levels. Retinoid-treated cells showed a marked downregulation of CD71 and a decreased S-phase compartment with a parallel accumulation in Gzero/ G1 phases. These cell cycle perturbations were associated with the upregulation of p27 Kip1, a nuclear protein that controls entrance and progression through the cell cycle by inhibiting several cyclin/cyclin-dependent kinase complexes. Unlike what is observed in other systems, the antiproliferative effect exerted by retinoids on LCLs was not due to the acquisition of a terminally differentiated status. In fact, retinoid-induced modifications of cell morphology, phenotype (downregulation of CD19, HLA-DR, and s-Ig, and increased expression of CD38 and c-Ig), and IgM production were late events, highly heterogeneous, and often slightly relevant, being therefore only partially indicative of a drug-related differentiative process. Moreover, EBV-encoded EBV nuclear antigen-2 and latent membrane protein-1 proteins were inconstantly downregulated by retinoids, indicating that their growth-inhibitory effect is not mediated by a direct modulation of viral latent antigen expression. The strong antiproliferative activity exerted by retinoids in our experimental model indicates that these compounds may represent a useful tool in the medical management of EBV-related lymphoproliferative disorders of immunosuppressed patients.

The role of molecular analyses of B-cell and T-cell clonality in the study of B-cell lymphomagenesis.

While the simple detection of B-cell clonality does not imply B-cell malignancy, comprehensive analyses of B-cell clonality are crucial to investigate the pathobiology of B-cell lymphoproliferative disorders. Our recent studies in patients with Sjögren's syndrome have highlighted how multiple molecular analyses of B-cell clonality (Southern blot, polymerase chain reaction, single strand conformation polymorphism, and DNA sequence analysis) in prelymphomatous lesions may be of great value in helping to define the stages of progression towards low-grade malignancy. The study of T-cell expansion may also be important in investigations of the pathobiology of the different stages of B-cell lymphoproliferation (fully benign, pseudolymphomatous, or definitely malignant), which may still be T-cell-and antigen/ autoantigen-dependent.

A CD5+ leukemic lymphoma with monocytoid features: an unusual B-cell lymphoma mimicking hairy-cell leukemia.

A case of lymphoma presenting with features shared by hairy cell leukemia (HCL) and its variant, intermediate lymphocytic lymphoma (ILL) and monocytoid B-cell lymphoma (MBCL) is described. Clinical presentation and the morphological findings observed in peripheral blood and in bone marrow biopsy suggested an HCL; however, the tartrate-resistant acid phosphatase negativity of peripheral blood lymphocytes, the histologic pattern observed in the spleen, and the immunophenotyping of peripheral blood, spleen and bone marrow neoplastic lymphocytes (expression of CD5 and lack of CD25), were strongly against this hypothesis. The clinical course was aggressive. This report emphasizes the concept of the equivocal presentation of some 'low-grade' B-cell lymphomas. It is further pointed out that, even with complete and exhaustive morphological and immunological analyses, atypical cases may be encountered.

Transbronchial biopsy in sarcoidosis: the role of immunohistochemical analysis for granuloma detection.

In this study 27 transbronchial biopsy specimens obtained from patients with clinical and/or laboratory features suggestive for sarcoidosis were analysed with conventional morphology and immunohistochemistry comparing the sensitivity and reproducibility of the two methods. A limited panel of monoclonal antibodies recognizing epitopes resistant to conventional fixation and embedment procedures were used (CD45R0, CD68, anti-cheratin, anti-collagen IV). All specimens were independently observed by two different pathologists. On the basis of the recognition of bona-fide noncaseating granulomas, 9 cases were uniformly judged as positive, 10 cases as negative, but 8 cases were considered doubtful. Immunohistochemical analysis reliably demonstrated the presence of epithelioid cells in 3 of these cases and absence in 5. These data suggest that the use of a limited immunohistochemical analysis can significantly improve histological diagnosis of sarcoidosis on small transbronchial biopsies using conventional routine material.