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Biomedical subjects

C Bona

Publications and source records attributed to C Bona.

At least 127 records · Page 7Linked to original sources
PubMed1979

Cellular basis of regulation of expression of idiotype. I. T-suppressor cells specific for MOPC 460 idiotype regulate the expression of cells secreting anti-TNP antibodies bearing 460 idiotype.

An idiotype of the dinitrophenyl-binding myeloma protein MOPC 460 was expressed on a small but significant proportion of anti-TNP antibodies which appeared after in vivo or in vitro immunization of BALB/c mice with three T-independent TNP antigens. In vitro experiments show that the depletion of T cells before culture increased significantly the number of plaques secreting anti-TNP antibodies bearing MOPC 460 idiotype (460Id). T cells from BALB/c mice, but not from C.B20 mice, exhibit this suppressor activity. Plate-binding experiments indicate that the suppressive action of the T-lymphocyte population depends on a cell which can bind to MOPC 460 myeloma protein. The possible role of these normally occurring, idiotype-specific T cells on expression of 460Id in the anti-TNP antibody response of BALB/c mice is discussed.

Animals↗
PubMed1979

Immune response to levan. II. T independence of suppression of cross-reactive idiotypes by anti-idiotype antibodies.

Pretreatment of BALB/c mice with antisera to a cross-reactive idiotype (E109IdX) expressed on many anti-bacterial levan (BL) and anti-inulin (Inu) antibodies leads to a prolonged suppression in production of IdX-bearing molecules in response to BL immunization. There is a comparable suppression in numbers of plaque-forming cells secreting IdX-bearing anti-BL and anti-Inu molecules. Furthermore, spleen cells from anti-E109IdX pretreated mice are unable to transfer to irradiated recipients the ability to produce IdX-bearing anti-BL and anti-Inu antibodies. These results indicate that the suppressive effect is at the precursor level and not simply a clearance of antibodies bearing the IdX. Suppression of IdX production can be achieved by pretreating nu/nu BALB/c mice with anti-E109IdX antibodies. Furthermore, spleen cells from pretreated mice do not inhibit the capacity of spleen cells from normal mice transferred to irradiated recipients to produce E109IdX in response to BL. This indicates that the suppression of IdX production in the anti-BL system is T independent and probably represents direct inhibition of precursors by anti-IdX.

Animals↗
PubMed1978

Mitogenic analysis of murine B-cell heterogeneity.

The B-cell mitogens lipopolysaccharide (LPS), Nocardia water-soluble mitogen (NWSM), and dextran sulfate (DxS) react with different subpopulations of B lymphocytes. Selective in vitro killing of cells responding to either LPS or NWSM has little effect on the in vitro response to the other mitogen, although the response to DxS is reduced in both cases. If, after selective in vitro killing, cells are injected into irradiated mice for 2-3 wk before measuring their in vitro mitogen responses, the same specificity pattern is seen. Thus, one is dealing with different B-cell subpopulations rather than different stages of maturation of a single population. Treatment with various alloantisera and complement before measuring the mitogen response to LPS and NWSM shows that (a) whereas all LPS response cells carry surface Ig, a subpopulation of NWSM responsive cells does not; (b) both LPS- and NWSM-responsive cells carry I-A antigens but might not I-E or I-J antigens; (c) all LPS-responsive cells carry I-C antigens, whereas approximately 25% of NWSM responsive cells do not: (d) there is a subpopulation of NWSM-responsive cells carrying neither surface Ig nor I-C antigens and resistant to anti-theta treatment.

Animals↗
PubMed1977

Release from maternally-induced allotypic suppression in rabbit by Nocardia water-soluble mitogen.

The in vitro synthesis of allotypes of b4/b5 offspring obtained from b4/b4 mothers immunized against paternal allotype b5/b5 was studied in comparison to similar offspring that had escaped from suppression and normal heterozygous b4/b5 rabbits. Nocardia water-soluble mitogen-a rabbit B-cell mitogen which is known to induce the differentiation of small lymphocytes into plasma cells and polyclonal activation of Ig, was able to break in vitro the allotypic suppression induced in vivo.

Animals↗
PubMed1977

Purification of rabbit T-derived (Ig-) lymphocytes.

Rabbit peripheral blood cells were rosetted by means of mixed agglutination technique described by Coombs et al. and the unrosetted Ig-, T-derived lymphocytes were separated in Ficoll-Triosil gradient. The cells which did not rosette in mixed agglutination reaction represented highly purified T-derived (Ig-) lymphocytes, as evidence by their response to T and B rabbit cell mitogens, their cytotoxic reactivity versus rabbit thymus lymphocyte antiserum (RTLA), and by failure to be stained with labelled anti-rabbit immunoglobulins antibodies and antibodies against allotypic specificities of the a and b series.

Animals↗
PubMed1977

Inhibition of mixed lymphocyte reactions in humans after immunization with tetanus toxoid.

Immunization of humans with tetanus toxoid (TT) results in an inhibition of the reactivity of peripheral lymphocytes to TT as well as to one-way mixed lymphocyte reaction. The strongest inhibition was observed in cells taken 3 or 7 days after immunization. These reactivities reappeared on the 14th day and reached their initial levels by the 21st day after immunization. The role of the various cell types was studied by culturing separately purified T or B lymphocytes taken on day 7 after immunization. B cells alone are not stimulated by TT or allogeneic cells. Purified T cells are stimulated much more than the initial total cell population. When B cells were mixed and cultured along with T cells, a suppressor effect upon stimulation appeared which reduced 3H-thymidine incorporation to the levels of the initial population. Treatment with 5-bromodeoxyuridine followed by exposure to light of cells stimulated with TT abrogated their ability to respond to subsequent stimulation with TT; whereas the responsiveness of treated cells to allogeneic lymphocytes was not significantly affected and vice versa. These results suggest that each stimulator activated a separate population of T cells but that in vivo immunization provoked the development of both a specific and nonspecific suppressor activity. Most probably this suppressor activity was brought about by adherent, surface Ig-bearing (B) cells.

Adult↗
PubMed1977

Damage of liposomes in antibody-dependent cell-mediated cytotoxicity.

Lymphoid cells bearing Fc receptors are able to lyse antibody-coated animal target cells in an antibody-dependent cell-mediated cytotoxicity reaction. The results presented here show that liposomes consisting of sphingomyelin, cholesterol, and cardiolipid and coated by cardiolipidic antibodies could be destroyed by spleen or thymus cells. No alteration of liposomes was observed when normal rabbit serum was used or when the effector cell population was depleted of cells bearing Fc receptors. The lysis of antibody-coated liposomes by effector cells could be carried out in two steps. In the first step, the fixation of antibodies on the cardiolipidic antigens could lead to a reorganization of the liposomal membrane. In the second step, the effector Fc-receptor-bearing cells might amplify this alteration of the liposomes.

Animals↗