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Several phenotypic changes have been shown to occur after NK-cell stimulation, involving molecules that have been proved to regulate NK-cell migration into tissues and NK-cell activation and proliferation as well as target cell recognition and killing. Here, we review the reactive phenotypes observed in vivo after acute and chronic NK-cell activation.

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We report a case of CD8(+)/V beta 5.1(+) T-cell large granular lymphocyte leukemia (T-LGL leukemia) presenting with mild lymphocytosis, severe autoimmune neutropenia, thrombocytopenia, polyarthritis and recurrent infections with a chronic disease course. Immunophenotyping showed an expansion of CD3(+)/TCR alpha beta(+)/CD8(+bright)/CD11c(+)/CD57(-)/CD56(-) large granular lymphocytes with expression of the TCR-V beta 5.1 family. Southern blot analysis revealed a clonal rearrangement of the TCR beta-chain gene. Hematopoietic growth factors, high dose intravenous immunoglobulin and corticosteroids were of limited therapeutic benefit to correct the cytopenias. During the disease course, the patient developed a severe cutaneous leg ulcer and bilateral vascular mammary skin lesions. Treatment with 2-deoxycoformycin resulted in both clinical and hematological complete responses, including the resolution of vascular skin lesions. Combined immuno-staining with relevant T-cell associated and anti-TCR-V beta monoclonal antibodies proved to be a sensitive method to assess the therapeutic effect of 2-deoxycoformicin and to evaluate the residual disease.

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At present, a major challenge in the initial diagnosis of leukemia of large granular lymphocytes (LGLs) is to establish the clonal nature of the expanded population. In the present study we have analyzed by flow cytometry immunophenotyping the TCR-Vbeta repertoire of 98 consecutive cases of persistent expansions of CD4(+) or CD8(+bright) CD3(+)/TCR-alphabeta(+) LGLs and compared the results with those obtained in molecular studies of TCR-beta gene rearrangements. Fifty-eight cases were considered to be monoclonal in molecular studies whereas in the remaining 40 cases there was no evidence for monoclonality (11 cases were considered oligoclonal and 29 polyclonal). The TCR-Vbeta repertoire was biased to the preferential use of one or more TCR-Vbeta families in 96% of cases, a total of 124 TCR-Vbeta expansions being diagnosed: one TCR-Vbeta expansion in 71 cases and two or more TCR-Vbeta expansions in 23 cases. The highest TCR-Vbeta expansion observed in each case was higher among monoclonal (74 +/- 19%) as compared to nonmonoclonal cases (24 +/- 14%) (P = 0.001), as did the fraction of LGLs that exhibited a TCR-Vbeta-restricted pattern (86 +/- 16% and 42 +/- 23%, respectively; P = 0.0001); by contrast, the proportion of cases displaying more than one TCR-Vbeta expansion was higher in the latter group: 7% versus 48%, respectively (P = 0.001). Results obtained in oligoclonal cases were intermediate between those obtained in polyclonal and monoclonal cases and similar results were observed for CD4(+) as for CD8(+bright) T-cell expansions. TCR-Vbeta families expressed in CD8(+bright) T-cell-LGL proliferations showed a pattern of distribution that mimics the frequency at which the individual TCR-Vbeta families are represented in normal peripheral blood T cells. Assuming that a given proliferation of LGLs is monoclonal whenever there is an expansion of a given TCR-Vbeta family of at least 40% of the total CD4(+) or CD8(+bright) T-cell compartment, we were able to predict clonality with a sensitivity of 93% and a specificity of 80%. By increasing the cut-off value to 60%, sensitivity and specificity were of 81% and 100%. In summary, our results suggest that flow cytometry immunophenotypic analysis of the TCR-Vbeta repertoire is a powerful screening tool for the assessment of T-cell clonality in persistent expansions of TCR-alphabeta(+) LGLs.

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In the present study we have compared the immunophenotypic characteristics of the CD56+lo and CD56+hi NK-cell subsets in a group of normal healthy adults. Our results show that CD56+hi NK-cells display greater light-scatter properties than CD56+lo NK-cells at the same time they have higher levels of CD25 and CD122 IL-2 chains, together with a higher reactivity for HLA-DR and CD45RO and lower levels of CD45RA, supporting that, as opposed to the majority of the CD56+lo population, CD56+hi NK-cells might correspond to a subset of activated circulating NK-lymphocytes. Higher expression of the CD2 and CD7 costimulatory molecules found for the CD56+hi NK-cells would support their greater ability to respond to various stimuli. In addition, CD56+hi NK-cells expressed higher levels of several adhesion molecules such as CD2, CD11c, CD44, CD56, and CD62L compared to CD56+lo NK-cells, supporting a particular ability of these cells to migrate from blood to tissues and/or a potential advantage to form conjugates with target cells. Interestingly, CD56+lo and CD56+hi NK-cells showed a different pattern of expression of killer receptors that might determine different activation requirements for each of these NK-cell subsets. For instance, absence or low levels of CD16 expression might explain the lower antibody-dependent cytotoxicity activity of CD56+hi NK-cells. On the other hand, the virtual absence of expression of the CD158a and NKB1 immunoglobulin-like and the greater reactivity for the CD94 lectin-like killer receptors on CD56+hi in comparison to CD56+lo NK-cells might determine different MHC-class I specificities for both NK-cell subsets, a possibility that deserves further studies to be confirmed.

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We report the clinical and laboratory findings of a patient with an aggressive Epstein-Barr virus positive CD2+/CD56+ natural killer-cell lymphoma with a high mitotic activity and complex chromosomal abnormalities presenting with life-threatening pericardial and pleural effusions, disseminated skin lesions, breast nodule and large suprarenal masses. The clinical course was characterized by resistance to chemotherapy and relapsing pericardial and pleural effusions with respiratory and haemodynamic failure. Death occurred 4 months after the first manifestations of the disease as a consequence of cardiac tamponade.

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In this paper we report a rare association of a splenic marginal zone B-cell lymphoma with villous lymphocytes and a T-cell large granular lymphocytic leukemia coexpressing CD4 and CD8 as well as CD56 and CD57 natural killer-associated markers in an asymptomatic patient investigated because of an occasional finding of erythrocytosis and leukocytosis in routine blood analysis. We also discuss the possible reasons for this particular association.

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We describe the immunophenotypic and gross DNA defects in 55 patients with myeloma and 50 patients with monoclonal gammopathy and review the literature on this subject (MedLine, 1994-2000). Our data confirmed previous reports indicating that in myeloma nearly all marrow plasma cells are abnormal (98.7 +/- 8.1%). In monoclonal gammopathy the fraction of abnormal plasma cells was 35.0 +/- 32.8%. In both myeloma and monoclonal gammopathy, the most frequent aberrant phenotypic features consisted of absence of expression of CD19, strong expression of CD56, and decreased intensity of expression of CD38; aberrant expression of CD10, CD20, CD22, or CD28 was observed in less than one-third of myeloma cases. The vast majority of cases had two or more phenotypic aberrations. In the DNA studies, 7% of myeloma cases were biclonal and 93% of cases were monoclonal. In those studies with only one plasma cell mitotic cycle, 37% had normal DNA content and 63% were aneuploid (hyperploid, 61%; hypoploid, 2%). The mean percentages of plasma cells in S- and G2M phases were 4.9 +/- 8.5 and 4.4 +/- 6.9%, respectively. Thirty-eight percent of cases had more than 3% of plasma cells in S phase. In monoclonal gammopathy, the DNA index of abnormal plasma cells ranged from 0.89 to 1.30 and the percentage of diploid (31%) and aneuploid (69%) cases was not different from the results found in myeloma. The differences in percentage of abnormal plasma cells in S- (7.4 +/- 8.6%) and G2M-phases (2.4 +/- 1.7%) in patients with monoclonal gammopathy were not statistically significant.

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We compared the expression of the BCL-2 oncoprotein (p26) on B cells from 24 patients with splenic lymphoma with circulating villous lymphocytes (SLVL) with that observed on normal, mature B lymphocytes and on neoplastic B cells from 91 patients with other chronic B-cell malignancies. SLVL B cells showed levels of p26 intermediate between those found on normal B lymphocytes and on neoplastic B cells from patients with other chronic B-cell lymphoproliferative disorders.

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The bcl-2 oncogene has been involved in the genesis of various B-cell neoplasms by means of encoding for p26, an apoptosis suppressor oncoprotein. The expression of p26 in lymphoproliferative disorders of large granular lymphocytes (LDLGL), a group of diseases whose mechanism leading to lymphocyte expansion is not yet clear, was not previously characterized. In order to further understand the biology of LDLGL, we compared the expression of p26 in CD8(+) lymphocytes of patients with CD3(+) LDLGL with that observed in normal individuals, patients with viral infection and patients with CD4(+) lymphoid neoplasms. We observed that upregulation of bcl-2 expression is not involved in the genesis of lymphocyte expansion in CD3(+) LDLGL. By contrast, when compared to normal peripheral blood counterparts, CD8(+, bright) lymphocytes of patients with LDLGL express low levels of p26 whereas CD8(+, dim) lymphocytes express normal or only slightly reduced levels of this oncoprotein. A similar pattern of expression of p26 was found in situations in which CD8(+) lymphocytes represent reactive activated cells.

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A survey of 2036 strains of Escherichia coli was conducted in Oporto, Portugal, to establish the prevalence of resistance to beta-lactam antibiotics. Isolates were from hospital and clinical practice patients, and were further divided into urinary and non-urinary pathogens. A high level of resistance to aminopenicillins (55.3%) was observed. Further examination of the resistant strains showed that the frequencies of occurrence of known beta-lactamases were as follows: TEM-1 (78.2% of resistant strains); SHV-1 (7.9%); TEM-2 (0.45%); OXA-1 (1.5%); HMS-1 (0.18%); TEM-1 + SHV-1 (4.2%). Other pairs of beta-lactamases were also identified in less than 2% of the resistant strains. In addition, 4.7% of the resistant strains produced elevated levels of a presumed chromosomal cephalosporinase, while 0.9% produced a ceftazimidase of pI 5.8-5.9 which was similar to TEM-6.

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