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M H Claësson

Publications and source records attributed to M H Claësson.

At least 37 records · Page 2Linked to original sources
PubMed1986

Proliferative kinetics, phenotype and cytotoxic function of thymic and peripheral T-cell colonies.

Cells produced in murine T-cell colonies grown in methylcellulose have been studied to evaluate their proliferation, phenotypic differentiation, and ability to give rise to cytotoxic cells. Colony-forming cells from presumably cortical or medullary thymocytes, separated by peanut agglutination, or from lymph nodes, showed rapid proliferation regardless of their origin, although cortical thymic colony cells showed significantly slower proliferation from day 10 to day 12 of culture. Essentially all the colony cells maintained the Lyt-1+2+ phenotype of the colony-forming cells, and no L3T4+ cells were found. The colony cells were characterized as rather mature cells by being strongly H-2-positive, and, except for a few cells, by lacking the TL antigen. Colony cells maintained the Lyt-1+2+ phenotype after expansion in liquid culture, and both cortically and medullary derived colony cells showed lectin-dependent cytotoxic activity against P-815 tumour cells. We conclude that our assay for growing thymus-derived T-cell colonies results in the proliferation of a phenotypically and functionally relatively mature cytotoxic T-lymphocyte progeny.

Animals↗
PubMed1985

T-lymphocyte colony formation by thymic and peripheral lymphocytes in methylcellulose culture.

A new method for one-step and one-layer culture of T-lymphocyte colonies (TLCs) from murine thymocytes and peripheral T-cells in methylcellulose is described. TLCs are detected from day 4 of culture and may contain up to 10(4) cells per colony. As few as 1 X 10(3) cells per culture can be seeded, and presented data indicate that individual colonies are the progenies of single cells. The frequency of colony-forming cells (CFCs) is about one per 6 000 thymic or splenic cells and one per 3 000 lymph node cells. A series of experiments was performed to study the nature of the CFC and the colony-cells, and it is concluded that the CFC is a Thy-1.2. positive, non-adherent, relatively hydrocortisone resistant, radiosensitive T-cell, the vast majority being in G1 or G0 phase, while colony-cells are Thy-1.2. positive, predominantly Lyt-2 positive cells in rapid cell-cycle. This method for growing thymic cells makes it possible to study differentiation and functional restriction of subsets of thymocytes on a clonal basis, and the culture system may also be a valuable source of monoclonally expanded lymphoid cells for future immunological studies.

Animals↗
PubMed1984

Functional heterogeneity in allospecific cytotoxic T lymphocyte clones. I. CTL clones express strong anti-self suppressive activity.

Five out of five allo-specific cytotoxic T lymphocyte (CTL) clones tested strongly suppressed the development of CTLs directed against the H-2 haplotype of the CTL clone and independent of the H-2 specificity recognized by the CTL clone. This was shown by including 100-1,000 cells from the five clones in one way mixed lymphocyte reaction (MLR) cultures in which the stimulator cells were of the same H-2 type as the CTL cells. When these cultures were assayed for cytotoxicity against the stimulator cell haplotype, the cytotoxic activity was decreased in a CTL cell dose-dependent manner by 50 to more than 90%. Suppression was usually not observed in MLR cultures where the CTL-H-2 type was identical with the responder cells or was different from both the responder or stimulator cells. Suppression was demonstrated not to be due to "cold" target inhibition at the time of cytotoxicity assay. Even if the added CTL were completely removed after 48-72 h of culture, significant suppression was obtained. Suppressive ability did not appear to be correlated with the level of allo-specific cytotoxic activity present in the CTL clones, but might involve direct killing of MLR precursor cells by cells in the added CTL clones. The suppression observed here, which is anti-self from the point of view of the added CTL clone, appears to be triggered by precursor cells in the MLR responder population recognizing MHC determinants on cells from the added CTL clone. This peculiar type of suppression, in which the regulator regulates on being recognized, has been christened the veto phenomenon and may play a role in maintenance of self tolerance.

Animals↗
PubMed1984

In vitro effect of interferon on development and function of bone-marrow-derived cytotoxic diffuse colonies.

The present work shows that addition of mouse beta interferon (IFN) to murine bone marrow cells cultured in the presence of pokeweed mitogen-spleen-CM results in an increase in the proportion and number of diffuse colonies. Addition of IFN early in the culture period inhibits the development of the cytotoxic capacity typical for normal diffuse colonies. Addition of IFN late in the culture period, when diffuse colonies have already been formed, enhances the cytotoxic activity of individual colonies. The cellular composition of diffuse colonies was nearly identical in non-cytotoxic and strongly cytotoxic colonies. It is concluded that IFN profoundly affects development and function of cytotoxic diffuse colonies.

Animals↗
PubMed1984

Colony formation by subpopulations of human T lymphocytes. V. Helper and suppressor activity of cloned human T-cell lines.

Twelve human T-cell lines were derived from cultures stimulated with phytohaemagglutinin (PHA) or with the recall antigen purified protein derivative (PPD), using the one-step agar colony method, followed by further expansion of individual T-cell colonies for at least 50 days. As judged by monoclonal antibodies, two of the PHA-derived T-cell lines carried the helper-inducer (H-I) phenotype and two the suppressor-cytotoxic (S-C) phenotype. Four PPD-derived cell lines displayed the H-I phenotype, and three of these proliferated specifically when challenged with the recall antigen, whereas the fourth did not. Four PPD-induced T-cell lines carried the S-C phenotype, and only one of these was antigen-specific. All cell lines with H-I phenotype displayed helper cell activity as determined by Ig secretion of B lymphocytes stimulated with a T-cell-dependent polyclonal B-cell activator. Cell lines with the S-C phenotype had no such helper activity and suppressed Ig responses in the presence of freshly isolated T cells. Thus, a good correlation between phenotypic markers and functions was found. T helper cells and T suppressor cells can be differentiated by means of both polyclonal and antigenic stimuli.

Antibody-Producing Cells↗
PubMed1984

Mouse B- and T-cell colony formation in vitro. I. Separation of colony-promoting and -inhibiting activities in concanavalin A rat spleen conditioned medium.

Rat spleen cell cultures exposed for 24 h to concanavalin A (Con A-CM) contain, in addition to interleukin 2 (IL-2), factors that promote colony formation in vitro by mouse T cells (TCPA) and B cells (BCPA). TCPA and BCPA are separable on a Sephadex G-75 column. TCPA has a molecular weight of 15,000 daltons and shows the same elution profile as IL-2. Absorption studies with Con A-activated T cells suggested that TCPA and IL-2 are the same entity. BCPA has an apparent molecular weight of 45,000 daltons and stimulates colony formation by B lymphocytes seeded at very low cell density (10(4) - 5 X 10(4) cells/ml). In contrast to TCPA, BCPA can only be demonstrated in gel-filtered material owing to the presence of B colony suppressor activities in crude Con A-CM. Two B colony inhibitory activities were demonstrated by AcA 34 chromatography of crude Con A-CM with molecular weights of 80,000-130,000 and about 50,000, respectively. Because of the specificity, simplicity and sensitivity of B and T colony formation these assay systems should be valuable tools for in vitro testing of biological activities regulating the immune system.

Animals↗
PubMed1983

Colony formation by subpopulations of human T lymphocytes. III. Antigenic phenotype and function of colony-forming cells, colony cells, and their expanded progeny.

The antigenic phenotype of individual PHA-induced T lymphocyte colonies was studied with a direct immunofluorescence technique using fluorescein-labeled anti-Leu-2a and anti-Leu-3a antibodies. Of the colonies grown from mononuclear peripheral blood cells 85% were Leu-3a+ (inducer/helper phenotype), 12% were Leu-2a+ (suppressor/cytotoxic phenotype), and 3% contained equal numbers of Leu-2a+ and Leu-3a+ cells. Fluorescence-activated cell sorter (FACS) separated T-cell subsets showed that Leu-2a+ cells and Leu-3a+ cells form exclusively Leu-2a+ and Leu-3a+ colonies, respectively. Leu-3a+ cells formed colonies in both the absence and presence of conditioned medium (PHA-CM), whereas colony formation by Leu-2a+ cells was absolutely dependent on PHA-CM. Mixing experiments with FACS-separated T-cell subsets showed that Leu-2a+ cells inhibit colony formation by Leu-3a+ cells in a cell dose-dependent manner both in the presence and absence of PHA-CM. Phenotype analysis of individual colonies from mixing experiments strongly suggested monoclonal proliferation in the present colony assay system. The majority of expanded T-cell colonies showed helper activity in a reverse hemolytic plaque-forming B-cell assay, although to a lesser degree as compared to that of freshly isolated T lymphocytes.

Antibody Formation↗
PubMed1983

Colony formation by subpopulations of T lymphocytes. IV. Inhibitory effect of hydrocortisone on human and murine T cell subsets.

The sensitivity of human T lymphocyte colony formation to hydrocortisone (HCS) was studied in the presence and absence of an exogenous source of interleukin-2(IL-2). In the presence of IL-2, T colony formation by T inducer/helper (Th) cells was found to be 100-fold more resistant to the inhibitory effect of HCS in vitro than colony formation by T suppressor/cytotoxic (Tsc) cells, the IC50 values for HCS being 10(-4)M and 10(-6)M, respectively. In the absence of IL-2,Tsc cells do not form colonies and T cell colony formation by Th cells is inhibited 50% by less than 5 x 10(-8)M HCS. T lymphocyte colony formation by murine cortical thymocytes in vitro was inhibited by physiological concentrations of HCS in vitro, the IC50 value being 2 x 10(-8)M HCS. T cell colony formation by medullary thymocytes and peripheral lymphocytes was found to be 100-fold more resistant to HCS than control cells, the IC50 value being 2 x 10(-6)M HCS.

Animals↗
PubMed1982

Expanded progeny cells of diffuse cytotoxic bone marrow-derived colonies.

Bone marrow-derived (colony-stimulating factor [CSF]-dependent) diffuse colonies have been shown to include colonies with cytotoxic activity. Such diffuse colonies were expanded for 6-8 weeks in liquid culture medium in the presence of pokeweed mitogen- or concanavalin A-conditioned spleen cell medium (CM). The morphology of the expanded diffuse colony cells (EDCC) was like that of early myelocytic cells. EDCC lost their cytotoxic capacity when expanded, but the cytotoxicity could be reinduced by pretreatment of the colonies with interferon or phorbol ester. Traditional sources of mouse or human CSF such as lung CM, placenta CM and human mononuclear cell CM did not support proliferation of EDCC, whereas partly purified interleukin-3 (IL-3), lacking CSF and IL-2, was stimulatory for EDCC. Thus, the stimulatory factor for EDCC was not CSF but a factor closely related to IL-3. Monoclonal antibodies against T lymphocytes or macrophages did not bind to EDCC. EDCC did not have Fc receptors, but 10% of the cells were positive for a monoclonal anti-Ia antibody. All EDCC were positive for alpha NAE and NASDCI esterases but negative for acid and alkaline phosphatases and peroxidase reactivity; less than 2% of the cells showed metachromatic staining with toluidine. Ultrastructurally, EDCC showed various degrees of cell differentiation but absence of specific cytoplasmatic characteristics such as neutrophilic, eosinophilic, basophilic and mast cell granules. Current work aims to define factors and conditions necessary for the induction of differentiation in these immature monomyelocytic cells.

Animals↗
PubMed1982

T cell clones restricted to "hybrid" HLA-D antigens?

The genetics of T lymphocyte/accessory cell interactions were studied by using antigen-specific monoclonal T cell lines from human peripheral blood and X-irradiated non-T cells (E rosette-depleted) as accessory cells. The T cell lines were obtained by expanding single colonies from soft agar-cloned E rosette-positive lymphocytes, previously incubated for 3 days in liquid culture with 30% autologous X-irradiated non-T cells and antigen (PPD). When investigated with both autologous and allogeneic accessory cells of various HLA-D genotype, different sets of PPD-specific T cell lines were obtained from HLA-D heterozygous individuals; two sets restricted to each one of the two HLA-D antigens, and a third set responding to PPD only when presented by accessory cells carrying both HLA-D antigens possessed by the T cell donor. A few cell lines responded to PPD only in the presence of autologous accessory cells.

Clone Cells↗
PubMed1981

Colony formation by subpopulations of human T lymphocytes. II. Characteristics of colony cells and colony suppressor cells.

Phytohaemagglutinin-induced human T-lymphocyte colony formation in semisolid agar culture is the property of erythrocyte rosette-forming cells (E-RFC) negative for the 7S IgG receptor (FcR-). E-RFC positive for the 7S IgG receptor (FcR+), on the other hand, exhibit a limited capacity for colony formation and suppress colonies formed by FcR- E-RFC. T colonies are composed of small lymphocytes and lymphoblasts, the vast majority being negative for the Fc receptor. Most colony cells (86%) carry the Leu 3a antigen, suggesting that they belong to the inducer/helper T-cell subset. FcR+ colony suppressor cells are small, slowly sedimenting cells (sedimentation velocity less than 3.8 mm/h) and are strongly adherent to plastic, and their activity depends on the ability to synthesize DNA.

Colony-Forming Units Assay↗
PubMed1980

Autoreactive natural killer-like cells from agar-cloned murine bone marrow cells.

Natural surveillance against malignant cells has been ascribed to so-called natural killer (NK) cells. These cells attack tumour cells without prior antigen stimulation and may also be cytotoxic to non-malignant cells. NK cells are routinely demonstrated by their cytotoxic activity against various types of tumour cell in vitro, but elucidation of the characteristics of the cytotoxic cells has hitherto been hampered by the lack of techniques by which NK cells can be isolated. Here we demonstrate murine NK-like activity from bone marrow cells cloned in semi-solid agar medium for granulocyte-macrophage colony formation. Data obtained indicate that such procedures considerably improve the possibility of obtaining quite pure NK cell populations by which the NK cell phenomenon may be studied in more detail.

Animals↗
PubMed1980

B lymphocyte colony formation in vitro: ultrastructural development of individual colonies.

B lymphocyte colony development in agar culture was studied using an electron microscope, and more than 3,000 colony cells were identified and photographed. In early cultures (day 4) lymphoblasts dominated the colonies. From day 5 onwards plasmablasts and small lymphocytes were present in colonies. From day 6 onward mature plasma cells were observed in increasing numbers. On day 9 culture the colonies started to degenerate and on day 10 of culture approximately 70% of the colony consisted of pyknotic and degenerating cells. Topographically, the degenerating cells were concentrated in the center of the colony whereas proliferation took place in the periphery. Colony growth occurred in an exponential fashion, the number of viable colony cells being maximal on day 8 of culture (400-600 cells/colony). At this time the frequencies of the four B cell categories were: lymphoblasts 72%, plasmablasts 20%, plasma cells 6%, and small lymphocytes 2%. Recloning experiments showed that dispersed colony cells were capable of forming only small cell clusters. It is concluded that B lymphocyte colony formation reflects a series of B cell developmental stages including the formation of the end cell categories o this lymphocyte lineage.

Animals↗
PubMed1979

D-penicillamine: mitogenic effect on mouse, rat and human spleen lymphocytes.

The effect of D-penicillamine (D-Pen) on the proliferation of cultures of normal mouse, rat, and human spleen lymphocytes and peripheral blood lymphocytes was examined. D-Pen in concentrations of 2 x 10(-3) M to 8 x 10(-3) M in serum-free and in serum-containing medium resulted in a highly significant incorporation of 3H-TdR by normal mouse and rat spleen cells. Enhanced incorporation of 3H-TdR by normal human spleen cells only occurred in serum-containing medium. D-Pen in concentrations of 10(-4) M to 10(-3) M in serum-free and serum-containing medium resulted in significant inhibition of 3H-TdR incorporation by normal and mitogen-stimulated mouse and rat spleen cells. Doses of D-Pen greater than 2 x 10(-2) M strongly inhibited 3H-TdR incorporation by both normal and mitogen-stimulated mouse, rat, and human spleen cells and peripheral blood cells. The latter cells were not stimulated or inhibited at lower concentrations of D-Pen. Results from cell depletion and enriching procedures (specific antibody +C' cell killing, employment of athymic, nude spleen cells, adherent and phagocytic cell removal, E rosette cell separation procedures) suggested that target cells in the mouse spleen for D-Pen activation are non-adherent B cells whereas the D-Pen responsive cells in the human spleen probably are T cells.

Animals↗