C3-reacted sepharose: a preparative method for separating T and B lymphocytes.

Lymphocytes bearing complement receptors were separated from lymphocyte suspensions using C3-reacted Sepharose columns as solid phase immunoabsorbents. The retained CR+ lymphocytes were recovered by elution of the column with IgG fraction purified from a rabbit antiserum to human C3. This paper describes the method, its specificity and the yields of cells obtained.     

Lymphokine-activated killer cells, natural killer cells and cytokines

In the past year, natural killer cells have been the subject of much active investigation. The analysis of the effect of cytokines on the generation, proliferation and function of natural killer cells, and the definition of the lymphokines that they produce, have been particularly important areas of research in view of their possible application in adaptive immunotherapy, combined with biological response modifiers.     

Human peripheral CD2-/lo T cells: an extrathymic population of early differentiated, developing T cells

We previously reported that a subset of human peripheral blood CD3+ T cells expresses low-to-null CD2 levels (CD2-/lo), produces type 2 cytokines and is inducible to differentiate to functionally mature IFN-gamma+ cells. Multiple-color immunofluorescence analysis indicated that this population, representing <0.1% of the T cells in fresh lymphocytes, contains subsets that are phenotypically immature, including CD4-CD8- and CD3+TCR- cells. Ex vivo, the CD2-/lo cells can proliferate (carboxyfluorescein diacetate succinimidyl ester analysis) independently from exogenous stimulation, respond to CD3-mediated stimulation with significantly greater proliferation than the autologous mature cells and their subsets are inducible to undergo in vitro a developmental sequence similar to that reported for the phenotypically similar thymic populations. This is especially evident for the CD4+CD8+ subset. CD2-/lo T-cell populations exhibit a TCR repertoire (Vbeta chain distribution) that is complete but different (complementarity determining region R3 analysis) from that of the autologous CD2+ T cells. These characteristics distinguish peripheral CD2-/lo T cells as possible early differentiated T cells that may undergo extrathymic maturation, and potentially contribute to maintain the peripheral naive T-cell pool. These findings define the existence of phenotypically immature T cells in the periphery. Also, given the high numbers of CD2-/lo T cells generated, upon ex vivo culture, from peripheral lymphocytes of all adult and neonatal individuals tested, they have relevance to clinical applications for immune reconstitution of T cells, as well as myeloid cells, via myeloid colony-stimulating factors and type 2 cytokines.     

Final steps of natural killer cell maturation: a model for type 1-type 2 differentiation?

Analysis of cytokine and differentiation antigen expression in human natural killer (NK) cells revealed that interleukin 13 (IL-13) and interferon gamma (IFN-gamma) are produced at sequential stages during irreversible IL-12-induced differentiation. In human NK cell clones, polyclonal CD3-CD161+CD56- cells and peripheral lymphocytes, IL-4 induced the proliferation of both IL-13+ NK and T cells, whereas IL-12 allowed a proliferation-independent accumulation of IFN-gamma+ cells. These data disproved the NK1-NK2 hypothesis and challenge the current T helper 1 (TH1)-TH2 paradigm. We propose that the cytokine environment regulates a type 2-->0-->1 developmental progression, with IL-12 needed for terminal differentiation and IL-4 delaying this process, rather than a type 1 versus type 2 decision of a type 0 cell.     

Independent regulation of tumor necrosis factor and lymphotoxin production by human peripheral blood lymphocytes

We present evidence that human peripheral blood lymphocytes, free of contaminating monocytes, rapidly produce high levels of tumor necrosis factor (TNF) when stimulated with phorbol diester and calcium ionophore, and lower but significant levels of TNF when stimulated with mitogens. These two types of inducers act preferentially on T cells, both CD4+ and CD8+. NK cells produce TNF only when stimulated with phorbol diester and calcium ionophore, and they do so at a much lower level than T cells. The procedures used in the purification of lymphocytes and the differential ability to respond to various inducers allow us to exclude that monocytes or basophils contaminating the lymphocyte preparation participate in the production of TNF. In particular, LPS, a potent inducer of TNF production from monocytes, is unable to induce significant levels of TNF in the lymphocyte preparations. The TNF produced by lymphocytes has antigenic, physicochemical, and biochemical characteristics identical to those of the TNF produced by myeloid cell lines or monocytes upon stimulation with LPS. LT is also produced by lymphocyte preparations. Production of TNF and LT proteins in response to the different inducers is paralleled by accumulation of cytoplasmic TNF and LT mRNA. Both at mRNA and at protein levels, stimulation of T lymphocytes with phorbol diester and calcium ionophore preferentially induces TNF, whereas mitogen stimulation preferentially induces LT. Our data suggest that the TNF and LT genes, two closely linked genes encoding two partially homologous proteins with almost identical biological functions, are independently regulated in lymphocytes.     

Peripheral NK cell phenotypes: multiple changing of faces of an adapting, developing cell

We have defined the existence of developmental relationships among human peripheral NK cells with distinct phenotypic and functional characteristics. These findings closely parallel the changes that occur in vivo during NK cell development, and in vitro in experimental culture systems supporting NK cell generation from hematopoietic progenitors. These new insights provide a simplified framework to understand NK cell immunobiology and the cellular bases for their roles in innate immunity, initiation and maintenance of immune responses via regulation of adaptive and accessory cell functions, and immune pathologies.     

Gonadal and bone marrow doses in routine radiographic examinations of the skeleton in adults

Evaluations of gonad and bone marrow dose in standard skeletal radiographic investigations in adults are reported, and compared with previously published ones. A Rando phantom, condenser ionization chambers and thermoluminiscent dosemeters were used.     

Retinoic acid cooperates with tumor necrosis factor and immune interferon in inducing differentiation and growth inhibition of the human promyelocytic leukemic cell line HL-60

In this study, we analyzed the effect of tumor necrosis factor (TNF) on retinoic acid (RA)-induced myeloid differentiation of the promyelocytic HL-60 leukemia cell line. We show that low concentrations of the two substances, almost inactive in inducing differentiation when used separately, induce differentiation when added simultaneously to the cell cultures. Cells simultaneously expressing both monocyte/macrophage phenotype (typically induced by TNF) and granulocyte characteristics (typically induced by RA) are induced by a combination of the two factors, indicating that TNF and RA potentiate each other's activity. The results obtained using immune interferon (IFN-gamma) in combination with the two inducers suggest that the mechanism of action of TNF and IFN-gamma are possibly different. The inhibitory effect of RA on the expression of HLA class I antigens and of the high-affinity Fc receptor is potentiated by TNF but completely reversed by rIFN-gamma.