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Biomedical subjects

H Osawa

Publications and source records attributed to H Osawa.

At least 199 records · Page 11Linked to original sources
PubMed1984

Detection and localization by the monoclonal anti-interleukin 2 receptor antibody AMT-13 of IL 2 receptor-bearing cells in the developing thymus of the mouse embryo and in the thymus of cortisone-treated mice.

During embryonic development of the mouse, before expressing classical T cell markers, the blast cells colonizing the thymus react with the monoclonal antibody AMT-13 shown previously to detect interleukin 2 receptors. The proportion of AMT-13+ cells decreases as gestation time increases. On the other hand, the proportion of Thy-1+, Lyt-1+ and Lyt-2+ cells increases during ontogenesis. On the 19th day of gestation when the thymus architecture is comparable to the adult thymus, the AMT-13+ cells become localized in the subcapsular area of the cortex. In the adult thymus after cortison treatment the regenerating cells express the AMT-13 antigen. The AMT-13 antigen presumably the interleukin 2 receptor is the first marker of the early embryonic thymocytes reported until now that may be related to cellular function.

Animals↗
PubMed1984

Studies on the interleukin-2 receptor, its generation and dynamics using monoclonal anti-interleukin-2 receptor antibodies.

There is increasing evidence suggesting that the monoclonal antibodies ART-18, AMT-13 and anti-Tac recognize species-specific antigenic determinants of the interleukin-2 (IL-2) receptors of rat, mouse and human origin, respectively. In order to compare directly the molecules (glycoproteins) recognized by these antibodies, concanavalin A (ConA) activated T-lymphocytes of the respective species were surface labeled with 125I, after which the materials immunoprecipitated by the appropriate anti-IL-2 receptor antibodies were subjected to SDS-PAGE analysis. The noncross-reacting antibodies ART-18 and AMT-13 both precipitated a 50-55-kD molecule. The anti-Tac-reactive material (the putative human IL-2 receptor) is considerably different (60-65 kD) from those precipitated by antibodies ART-18 and AMT-13 (the putative rat and mouse IL-2 receptors). An indirect binding assay using the anti-mouse IL-2 receptor antibody AMT-13 showed that, after addition of ConA to spleen cell cultures, T-lymphocytes expressed IL-2 receptors before the onset of the ConA-induced DNA synthesis. The ConA-induced expression of the IL-2 receptor is apparently a transient event. IL-2 receptor bearing cells progressively lost their receptors (within 6 days) when recultured in the absence of ConA. Cells re-exposed to ConA regained IL-2 receptors. Short exposure of T-cells (thymocytes) to ConA or the nonmitogenic compound phorbol myristate acetate (PMA) is not sufficient to trigger IL-2 receptor expression. Murine thymocytes incubated with PMA for 30 min or with ConA for 4 hr (mitogen-pulsed T-cells) failed to bind the anti-IL-2 receptor antibody AMT-13 and to absorb IL-2 activity present in semipurified IL-2 preparations, but they proliferated vigorously in response to the same IL-2 preparations. The IL-2 preparations, when absorbed with thymocytes, lost: (1) the capacity to generate IL-2 receptors, and (2) the capacity to induce proliferation of mitogen-pulsed cells; but they retained the capacity to induce proliferation of T-lymphoblasts. These results suggest the existence of a factor, IL-2 receptor inducing factor (RIF), present in the IL-2 preparations. It is postulated that RIF is a prerequisite for the acquisition of IL-2 receptors and consequently for IL-2 responsiveness by lectin-activated cells.

Animals↗
PubMed1984

Interleukin 2 receptors on an insulin-specific T cell line: dynamics of receptor expression.

Long-term cultured T blasts with specificity for bovine insulin (BK-BI-1.2), which cease growing in IL 2 supplemented medium and require periodic antigenic challenge to resume proliferation, were selected as a model system to analyze the regulation of the growth of activated T cells. The use of AMT-13, a monoclonal antibody (mAb) directed at the murine IL 2 receptor, in indirect binding experiments and in FACS analysis allowed us to examine the time-dependent expression of IL 2 receptors on BK-BI-1.2 blasts after antigenic stimulation. The data reveal a transitory expression of IL 2 receptors, attaining maximal levels on day 2 after antigenic induction and having declined to low levels by day 6. mAb 10-2.16, reactive with I-Ak, did not inhibit T cell-proliferative capacity when the cells were subcultured in IL 2. This result suggests that, once induced to maximal levels by antigen, the transitory expression of IL 2 receptors on the descendent cells is not dependent on the continual presence of antigen-presenting cells. Thus, the progressive loss of IL 2 receptors apparently is not due to a mechanism operating by clearance of receptors from the cell surface on completion of each cell cycle, leading to dependency of the descendent cells on repeated contact with antigen for renewed receptor expression. The disappearance of IL 2 receptors from the surface of antigen-stimulated T cells might provide a basis for the control of immunologic specificity in vivo.

Animals↗
PubMed1984

A rat monoclonal antibody that binds specifically to mouse T lymphoblasts and inhibits IL 2 receptor functions: a putative anti-IL 2 receptor antibody.

To obtain an anti-interleukin 2 (IL 2) receptor antibody, we immunized rats with phorbol myristate acetate-pulsed mouse T lymphoblasts. The spleen cells of the rats were fused with rat myeloma cells. Several stable clones of hybridoma cells were obtained that produced monoclonal antibodies (mAb) reacting specifically with mouse T lymphoblasts. One of these mAb, AMT-13, showed characteristics of a putative anti-IL 2 receptor antibody. As tested by FACS analysis, the mAb AMT-13 binds to murine T lymphoblasts or to IL 2-dependent T cell lines, but not to B lymphoblasts, thymocytes, splenocytes, lymph node cells, or bone marrow cells. The mAb AMT-13 inhibited in a species-specific and dose-dependent manner: i) the capacity of mouse T lymphoblasts to absorb IL 2 activity, and ii) the capacity of mouse T lymphoblasts to proliferate in response to IL 2. The function of T lymphoblasts of rat origin was not affected by the mAb AMT-13. The time course of the acquisition by mitogen-stimulated spleen cells of the capacity to absorb IL 2 activity was paralleled by that of their capacity to bind the mAb AMT-13. Preliminary biochemical analysis of the antigen recognized by AMT-13 revealed a major component with an apparent m.w. of 50,000 to 60,000. According to these data, the mAb AMT-13 seems to be directed against an antigenic determinant of the murine IL 2 receptor molecule.

Animals↗
PubMed1983

The characteristics of a monoclonal antibody that binds specifically to rat T lymphoblasts and inhibits IL 2 receptor functions.

In order to obtain an anti-interleukin 2 (IL 2) receptor antibody, we immunized mice with phorbol myristate acetate-pulsed rat T lymphoblasts. The spleen cells of the mice were fused with myeloma cells. Several stable clones of hybridoma cells were obtained that produced monoclonal antibodies (mAb) reacting specifically with rat T lymphoblasts. Only one of these mAb, the mAb ART18, showed characteristics of a putative anti-IL 2 receptor antibody. This mAb was produced on a large scale, purified, and characterized. As tested by a binding assay, 125I-labeled mAb ART18 bound to rat T lymphoblasts (7.5 X 10(4) binding sites per cell), but not to thymocytes or spleen cells of rat origin, or to lymphoblasts, thymocytes, or spleen cells of murine origin. Only marginal binding to lipopolysaccharide-stimulated rat lymphoblasts was detected. The mAb ART18 inhibited in a species-specific and dose-dependent manner i) the capacity of rat T lymphoblasts to absorb IL 2 activity and ii) the capacity of rat T lymphoblasts to proliferate in response in IL 2. The function of T lymphoblasts of murine origin was not affected by the mAb ART18. The time course of the acquisition by mitogen-stimulated spleen cells of the capacity to absorb IL 2 activity was paralleled by that of their capacity to bind 125I-labeled mAb ART18. According to these data, the mAb ART18 seems to be directed against an antigenic determinant of the IL 2 receptor molecule.

Animals↗
PubMed1983

Studies on T lymphocyte activation. II. Monoclonal antibody inhibiting the capacity of rat T lymphoblasts to absorb and to respond to IL-2: an anti-IL-2 receptor antibody?

We describe the production and some of the properties of a monoclonal antibody which inhibits binding of Interleukin 2 (IL-2) to rat T lymphoblasts as well as the capacity of these lymphoblasts to proliferate in response to IL-2 of rat or murine origin. According to these criteria, the antibody seems to be directed against an antigenic determinant on the IL-2 receptor. The antibody, obtained from hybridomas derived from mice immunized with phorbol-myristate-acetate-pulsed rat T lymphoblasts, exhibited species specificity, indicating that IL-2 receptors of various species are not necessarily identical, even if they can respond to IL-2 from different species.

Animals↗
PubMed1982

Chitin: an immunological adjuvant and a polyclonal B-lymphocyte activator.

Chitin, a linear beta 1-4 linked poly-N-acetylglucosamine, enhanced the in vivo immune response of normal mice to sheep red blood cells, but not that of mice with thymic aplasia (nude mice). The compound is mitogenic for murine B lymphocytes but not for thymocytes or splenic T lymphocytes. Similarly to well-known polyclonal B-lymphocyte activators; e.g. lipopolysaccharide, chitin induces differentiation of B lymphocytes into antibody-forming cells in vitro.

Adjuvants, Immunologic↗
PubMed1982

[Comparative study on cefmetazole and cefazolin in the treatment of suppurative otitis media].

Cefmetazole (CMZ) was compared to cefazolin (CEZ) for efficacy and safety in the treatment of suppurative otitis media (including acute otitis media and chronic otitis media in acute aggravating stage) under well controlled clinical trials. The therapeutic effects were analyzed statistically in 172 patients (82 administered CMZ, 90 administered CEZ). The adverse reactions were also analyzed statistically in 199 patients (CMZ 99, CEZ 100) in whom the judgement was possible. 1. The efficacy rate of CMZ (72.3% for good to excellent response) was assessed by physicians in charge to be similar to that of CEZ (59.3%). This was the same being assessed by the committee, too (CMZ 64.6%, CEZ 56.7%). 2. When patients were classified into 2 groups (acute otitis media, chronic otitis media in acute aggravating stage) with respect to diagnosis, statistically significant difference in clinical efficacy assessed by physicians in charge was observed in the cases with chronic otitis media (CMZ, CEZ). In addition, the improvements of flares on the drum membrane and the mucous membrane of eardrum were significantly better in the CMZ group than in the CEZ group. 3. Bacteriologically, 16 cases (19.8%) of S. aureus were resistant to CEZ, while only 1 case (1.2%) to CMZ. CMZ was judged to be effective in 5 of the 6 cases in which CEZ-resistant strains were detected. 4. Side effects were found in 2 cases (2.0%) treated with CMZ: one complained of retching and abdominal pain and the other developed skin eruption. On the other hand, only 1 case (1.0%) developed skin eruption in the CEZ group. These results suggest that CMZ is a new antibiotic agent which is highly valuable in the treatment of suppurative otitis media.

Adolescent↗
PubMed1981

Treatment of postoperative respiratory distress syndrome.

We have studied 45 patients with postoperative adult respiratory distress syndrome (ARDS) who were treated by mechanical ventilation during the last four years. This period was divided into two periods, and the mortality and progress after treatment were analysed. The overall, mortality was 56%. In the first period this rate was as high as 76%, while in the second period this rate improved to 43%. This improvement in the second period was thought to have resulted from aggressive cardiorespiratory treatment and the diminution of infection. According to the course of ARDS after treatment, four types could be classified. Type 1 showed rapid improvement in respiratory function. Type 2 showed gradual improvement. Type 3 showed relapse of respiratory failure. Type 4 resisted mechanical ventilation. Patients of types 3 and 4 had extremely poor prognoses. Stricter management to avoid infection, specific treatment of multiple organ failure (which was seen frequently) seemed advantageous. High frequency positive pressure ventilation (HFPPV) may have some role in improving the respiratory function of the patients with ARDS.

Adult↗