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C M Hawrylowicz

Publications and source records attributed to C M Hawrylowicz.

31 records · Page 2Linked to original sources
PubMed1989

Activated platelets express IL-1 activity.

Suspensions of washed human platelets express IL-1 activity after activation with agents such as thrombin, collagen, ADP, or epinephrine as judged by the ability of the platelet suspensions to support the growth of a T cell line, D10.G4.1, which exhibits a growth requirement for IL-1. Unactivated platelets express little IL-1 activity. The IL-1 activity expressed by activated platelets appears to be entirely associated with the platelet surface. No IL-1 activity was detected in supernatants derived from suspensions of activated platelets. A mAb specific for IL-1 beta inhibited 90% of the activity expressed by thrombin-activated platelets, whereas a mAb specific for IL-1 alpha inhibited approximately 20% of the activity. A control mAb was without an effect. These results indicate that activated platelets express surface-associated IL-1 activity. Platelet surface IL-1 may provide a mechanism for altering in an extremely localized and rapid manner the properties of IL-1 responsive cells with which platelets come in direct contact during processes of inflammation and vessel wall damage.

Animals↗
PubMed1989

Regulation of antigen presentation. II. Anti-Ig and IL-2 induce IL-1 production by murine splenic B cells.

Murine splenic B cells did not constitutively express IL-1 activity. After culture with anti-Ig and T cell-conditioned media and then fixation, B cells expressed membrane IL-1 and were able to stimulate growth of the IL-1-dependent T cell clone D10. Expression of membrane IL-1 required stimulation of B cells for 2 days before fixation. Significant IL-1 activity was detectable in freeze-thaw lysates of identical B cell preparations by 12 h. B cells also released IL-1 into the culture media. In situ hybridization studies by using probes to murine IL-1 alpha and IL-1 beta genes supported these observations. Thus, messenger RNA for IL-1 alpha and IL-1 beta rose in parallel, were detected between 6 and 24 h of culture, and declined to low levels by 30 h. Despite the presence of mRNA for IL-1 alpha and IL-1 beta, only IL-1 alpha had functional activity as determined by the use of a mAb to IL-1 alpha. IL-2 was found to be an essential component of the T cell-derived supernatant. Although IL-4 or TNF did not induce significant B cell IL-1 expression, they both caused a modest, but reproducible enhancement when added in combination with IL-2. IFN-gamma, by contrast, partially inhibited IL-1 induction.

Animals↗
PubMed1988

Regulation of antigen-presentation-I. IFN-gamma induces antigen-presenting properties on B cells.

B cells require activation to efficiently present Ag to T cells. In agreement with this earlier observation we show that live, mitomycin C-treated B cells, but not B cells fixed in paraformaldehyde, stimulated the growth of allogeneic T cells in the primary MLR. However, if B cells were cultured with anti-Ig antibodies and IFN-gamma before fixation they acquired excellent T cell stimulatory activity. Neither reagent alone conferred this novel co-stimulatory function on the B cell surface. The activity induced by both stimuli was not attributed to an increase expression of class II-MHC molecules or IL-1. IL-2 or IL-4, in combination with anti-Ig, also induced B cell stimulatory activity, but were less effective than IFN-gamma. TNF failed to stimulate B cells, but synergized with IFN-gamma in the induction of this activity. These studies therefore demonstrate an important role for lymphokines in modulating B cell Ag-presenting activity as well as the acquisition by B cells of a novel co-stimulatory surface activity.

Animals↗
PubMed1988

T helper cell subsets require the expression of distinct costimulatory signals by antigen-presenting cells.

We examined the ability of macrophages and B cells to function as antigen-presenting cells (APCs) for murine TH1 and TH2 cloned T helper cell lines. Antigen presented by concanavalin A-elicited peritoneal macrophages or resting splenic B cells stimulated antigen-dependent proliferation of both T helper subsets. Paraformaldehyde fixation of the APCs following different conditions of activation indicated differential requirements for costimulatory signals by TH1 and TH2 cells. TH2 proliferative responses were strictly dependent on APC expression of IL-1. TH1 proliferation was dependent on APC expression of a non-IL-1 costimulatory signal present on freshly isolated macrophages and on splenic B cells activated with anti-immunoglobulin plus interferon gamma.

Animals↗
PubMed1985

Activation and proliferation signals in mouse B cells. VI. Anti-Ig antibodies induce dose-dependent cell cycle progression in B cells.

Recent studies from several laboratories have shown that the concentrations of anti-immunoglobulin antibodies required to induce B lymphocytes to synthesize DNA are quite different from those needed to activate these cells, i.e. to cause resting B cells to leave G0. The present experiments examine this difference in detail. Thus, stimulation of DNA synthesis in mouse B cells requires prolonged (greater than 30 hr) exposures to high (greater than or equal to 10 micrograms/ml) concentrations of soluble F(ab')2 fragments of rabbit anti-Ig antibodies. However, as little as 50 ng/ml antibody caused B cells to enlarge, to express increased levels of Ia antigens, and to become primed to synthesize DNA more rapidly in response to restimulation with mitogenic concentrations of anti-Ig. The results of kinetic experiments suggested that the 'distance' that cells progress from G0 towards S depends not only on the time of exposure to anti-Ig, but also on its concentration. Concentrations of antibody less than 1 microgram/ml did not induce detectable RNA synthesis, and hence do not drive cells into the G1 phase of the cell cycle. Instead, under these conditions, B cells appear to enter a transitional, primed state (which has been termed GIT). This may well reflect the state into which T-dependent antigens drive resting B cells.

Animals↗
PubMed1984

Activation and proliferation signals in mouse B cells. I. A comparison of the capacity of anti-Ig antibodies or phorbol myristic acetate to activate B cells from CBA/N or normal mice into G1.

B lymphocytes from the CBA/N mouse do not synthesize DNA when cultured with anti-Ig antibodies. However, these cells like normal B cells, do manifest increased Ia antigen expression and RNA synthesis (i.e. enter G1) when stimulated by anti-Ig, even at doses which are nonmitogenic for normal B cells. Pretreatment of both normal and CBA/N B cells with anti-Ig also primes them to give an enhanced proliferative response to lipopolysaccharide (LPS). The tumor promoter phorbol myristic acetate (PMA) also enhances RNA synthesis and Ia antigen expression in B cells from both normal and CBA/N mice. However, PMA only primes CBA/N B cells to respond to LPS: pretreatment of normal B cells with PMA causes a modest suppression of LPS-induced, and a marked suppression of anti-Ig induced, DNA synthesis. These results therefore confirm and extend earlier data showing that there are distinct activating (G0 to G1) vs. proliferative (G1 to S) signals discernible in B cells. They also suggest that the activation mechanism of CBA/N B cells is subtly different from that of any known subpopulation of normal B cells.

Animals↗
PubMed1984

Activation and proliferation signals in mouse B cells. II. Evidence for activation (G0 to G1) signals differing in sensitivity to cyclosporine.

We have previously shown that cyclosporine (CS) selectively inhibits polyclonal activation of B cells by anti-Ig antibodies but not by lipopolysaccharide (LPS). Here we extend these results using a two-stage B cell culture system in which cells from either CBA/N or normal mice are activated to enter G1 by anti-Ig, and are then stimulated to proliferate by LPS. In this system CS blocks an event that occurs within 4 h after initial activation, i.e. prevents entry of B cells into G1. Phorbol myristic acetate also induces some CBA/N B cells to enter G1. However, activation of B cells by this agent is resistant to inhibition by CS. These data suggest that there are two biochemically distinct mechanisms for driving resting B cells into G1. A hypothesis to explain these results is presented.

Animals↗
PubMed1984

Activation and proliferation signals in mouse B cells. III. Intact (IGG) anti-immunoglobulin antibodies activate B cells but inhibit induction of DNA synthesis.

Intact (IgG) rabbit anti-immunoglobulin antibodies are generally not mitogenic for mouse B cells but, on the contrary, inhibit proliferation induced by either F(ab')2 anti-Ig or by lipopolysaccharide. We show here, however, that IgG anti-Ig activates mouse B cells, since it causes B cells to depolarize, to enlarge and to express increased levels of Ia antigens. In the continuing presence of IgG anti-Ig, B cells do not synthesise DNA. However, if cells cultured with IgG antibody are then washed, they start to proliferate earlier in response to F(ab')2 anti-Ig, i.e. they have become primed. We therefore conclude that IgG anti-Ig is an example of a 'step-one activator' for mouse B cells, which drives resting B cells out of Go, but actively prevents the cells from progressing into S. The latter effect appears to result from cross-linking of surface Ig and Fc receptors on B cells, although the mechanism is, as yet, unknown.

Animals↗
PubMed1984

Activation and proliferation signals in mouse B cells. IV. Concanavalin A stimulates B cells to leave G0, but not to proliferate.

Concanavalin A (Con A), in solution, induces mouse T cells, but not B cells, to proliferate. However, lectin concentrations which were optimal for the T cell response induced purified B cells to depolarize, to enlarge, and to display increased levels of Ia antigens. Furthermore, culturing B lymphocytes with Con A for 24 hr caused the cells to synthesize DNA more rapidly in response to subsequent stimulation by lipopolysaccharide, or anti-immunoglobulin antibodies. This priming effect did not appear to require either T cells or accessory cells. It was therefore concluded that Con A activates resting B lymphocytes, i.e. stimulates them to enter the cell cycle, even though it does not induce B cells to divide.

Animals↗
PubMed1984

Effects of tumour promoter phorbol myristate acetate on mouse lymphocytes: selective inhibition of B cell activation by mitogens and antigens.

The effect of the tumour promoter phorbol myristate acetate (PMA) on the responses of mouse lymphocytes to various stimuli was studied in vitro. Nanomolar concentrations of PMA inhibited B cell proliferation induced by lipopolysaccharide and by anti-Ig antibodies, and the polyclonal antibody response to lipopolysaccharide. Specific antibody responses to both T-dependent and T-independent antigens were similarly affected. In marked contrast, T cell proliferation elicited by various mitogens was 10- to 1000-fold more resistant to inhibition. Cell fractionation experiments suggest that the effects on B cell responses are the results of a direct anti-proliferative effect of PMA on responding B lymphocytes.

Animals↗
PubMed1983

Human spleen cells mediating natural killing: altered natural cytotoxicity of spleen effector cells from patients with carcinoma.

Spleen cells from eight patients with abdominal carcinoma and six patients undergoing major surgery for a variety of disease entities were assayed for natural cytotoxicity towards 51Cr-labelled K 562 target cells. Patients with abdominal cancer were shown to have relatively weak splenic natural cytotoxicity compared with the reactivity of effector cells from non-carcinoma patients. Nylon wool non-adherent spleen effector cells from cancer patients showed reduced cytolytic capacity compared with effector cells prepared from the spleens of other patients or peripheral blood mononuclear cells (PBMC) obtained from healthy individuals, whereas the splenic reactivity of non-cancer patients showed the same nylon wool separation profile as PBMC, high cytolytic activity being associated with nylon wool non-adherent effector cells. Splenic effector cell cytotoxicity from cancer and non-cancer patients was enhanced following exposure to human interferon, and inhibited by treatment with cholera toxin and simple sugars. Furthermore, fractionation of spleen cells on Percoll discontinuous density gradients demonstrated natural cytotoxic activity to reside predominantly in the low density cell fractions, similar to that found with NK cells from peripheral blood. Thus the properties described here for human cytotoxic spleen cells are similar to those described for peripheral blood NK cells, suggesting these two effector cell populations to be closely related, if not identical.

Adult↗
PubMed1982

Depressed spontaneous natural killing and interferon augmentation in patients with malignant lymphoma.

A substantial proportion (44%) of peripheral blood lymphocyte samples from 41 patients with malignant lymphoma have been shown to have depressed or undetectable levels of natural cytotoxicity against the leukaemic cell line K562 in a 4-hr [51Cr]-release assay. No correlation was found between low levels of natural killer (NK) cell activity and either the age of the patients, total or differential white blood counts, or the type or stage of disease. Furthermore, pre-treatment of lymphocytes with human lymphoblastoid (Namalva) interferon failed to enhance NK levels in 5/11 patients with Hodgkin's disease and 5/8 patients with non-Hodgkin's lymphoma, and was in contrast to the response of control peripheral blood lymphocytes assayed under the same test conditions. The lack of responsiveness to interferon of peripheral blood NK cells from lymphoma patients was not wholly associated with those patients shown to have low levels of spontaneous NK activity.

Adolescent↗