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Biomedical subjects

G Doria

Publications and source records attributed to G Doria.

At least 145 records · Page 8Linked to original sources
PubMed1978

Age-dependent variations of antibody avidity.

Age-dependent variations of antibody avidity were studied in the C3HeB/FeJ mouse. Spleen cells from donors of different ages (10--720 days) were transferred and stimulated with TNP-HRBC in lethally irradiated syngenic recipients. The anti-TNP antibody response of the donor cells was estimated from the number of direct PFC per recipient spleen by the Jerne technique with TNP-SRBC. Avidity of the antibodies secreted by PFC was evaluated from the amount of added TNP-BSA that inhibited 50% of the anti-TNP PFC. Under these experimental conditions allowing the exclusion of any influence of the donor milieu during the immune response, age-dependent variations of the antibody response and avidity could be attributed to changes in the donor spleen cell population. Avidity was found to increase with the response and to vary parabolically with age. After appropriate correction of the number of PFC to make it independent from age, avidity values were fitted by a multiple curvilinear regression in which the independent variables playing a significant role were the corrected number of PFC in its linear term and the age in its linear and quadratic terms. From comparison of the standard coefficients of this regression, the observed variations of avidity could be attributed in part (82%) to the response and in part (18%) to the age. For any value of response, avidity increased 15-fold from day 10 to reach a maximum at day 110 and then declined 5-fold at the age of 720 days. Heterogeneity of avidity also changed parabolically with age as high avidity classes were present in adulthood and absent at 10 and 720 days.

Aging↗
PubMed1978

Secretion rate independent evaluation of IgM antibody avidity at the level of single immunocytes.

The hemolytic plaque inhibition assay has been performed on spleen cells from mice immunized with TNP-HRBC to evaluate avidity of anti-TNP IgM antibodies. At different times after immunization direct plaques were inhibited by soluble TNP-EACA, TNP61-BGG, or anti-mu antiserum. Analysis of the inhibition data provided independent estimates of antibody avidity and secretion rate. Avidity was found to increase with time, to reach a maximum when the antibody response attained the peak value, and then to decline as the response was waning. There was a decrease followed by increase of the secretion rate concomitant with the rise and fall of the antibody response and avidity.

Aminocaproic Acid↗
PubMed1978

In vitro immune response of spleen cells from mice genetically selected for high or low antibody production.

The aim of this study was the identification of the cell type in which genes selected for high or low response to SRBC express their functions. Spleen cells from high (H) and low (L) responder mice were immunized with SRBC in the Mishell and Dutton system. An antibody response of different magnitude was found in cultures of H and L spleen cells, the difference being at least as great as that observed in vivo. This finding under experimental conditions allowing the exclusion of any influence of the animal milieu during the immune response, suggest macrophages, B, and T lymphocytes as possible target cells of gene action. In vitro cell separation and recombination experiments in which spleen cells were immunized with SRBC, TNP-LPS, or TNP-HRBC indicate that the genetic differences between H and L responders brought about by selective breeding are expressed in lymphocytes to greater extent than in macrophages. The role of histoincompatibility in the recombination experiments in unlikely but cannot be excluded. Among lymphocytes, B cells but not helper T cells were found more responsive in cultures of spleen cells from H than from L mice.

Animals↗
PubMed1977

Enhanced antibody affinity in sublethally irradiated mice and bone marrow chimeras.

Sublethally irradiated mice primed with dinitrophenyl (Dnp)-keyhole limpet hemocyanin immediately after irradiation or 30 days later and subsequently boosted with a second injection of antigen displayed a secondary response to Dnp characterized by antibody affinity greater than that in unirradiated controls. Also, in radiation chimeras primed with Dnp-keyhole limpet hemocyanin 120 days after syngeneic or allogeneic bone marrow transplantation the antibodies against Dnp produced after boosting were of higher affinity than the antibodies raised in normal mice. These findings are tentatively attributed to lack of suppressor thymus-derived lymphocytes (T cells) in sublethally irradiated mice and bone marrow chimeras, in which the enhanced ability to produce antibodies of high affinity may compensate for quantitative defects of the immune system.

Animals↗
PubMed1977

Effects of whole-body irradiation on antibody affinity.

Mice exposed to a sublethal dose of X-rays were immunized with alum-precipitated DNP-KLH (dinitrophenyl-keyhole limpet haemocyanin) and B. pertussis either before or after irradiation. The primary anti-DNP antibody response was evaluated during 8 weeks after immunization by the equilibrium dialysis technique using ammonium sulphate- precipitated serum globulins and the ligand 3H-labelled xi-DNP-L-Lysine. The serum concentrations of antibody sites in mice immunized 1-5 days before or 2 h-8 weeks after 450 rad were below the values in unirradiated controls at all bleeding times. Antibody affinity, however, was found to be up to 20 fold higher in irradiated mice than in control mice when antigen was injected before, or 3-8 weeks after, irradiation. Spleen cells from mice exposed to 450 rad 1-9 weeks before killing were stimulated in vitro with PHA, ConA, or LPS. Recovery profiles of mitotic responsiveness suggest that enhancement of antibody affinity in irradiated mice could result from relative lack of suppressor T Cells.

Animals↗
PubMed1976

Cell selection in the thymus of mice treated with escherichia coli lipopolysaccharide (LPS).

The present data indicate that injection of LPS induces a decrease in thymus weight with selection of thymocytes more efficient in killer and helper activities. It has been reported (12) that two T-cell types may cooperate in the GVH reaction: the effector T1 and the amplifier T2. The maturation from T1 to T2 occurs mainly in the periphery, whereas immature cortex thymocytes differentiate to T1 within the thymus (13). Our results, showing an LPS-dependent enhancement of thymocyte killing activity, suggest that LPS selects thymocytes mostly of the T1 type. LPS-treated thymocytes are more efficient in the reconstitution of the anti-SRBC response. These data can be explained considering that LPS, like cortisone (14), enriches the thymus with more immunocompetent helper cells. Alternatively it may be suggested that LPS selects in the thymus cell populations characterized by high proliferative activity. Unpublished observations showing that LPS-treatment in vivo increases the in vitro response of thymocytes to Con-A are consistent with this interpretation.

Animals↗
PubMed1976

Immune responsiveness and incidence of reticulum cell sarcoma in long-term syngeneic radiation chimeras.

Long-term syngeneic radiation chimeras displayed a very low incidence of reticulum cell sarcoma as compared with control mice. Immune reactivity of these animals was studied in vivo by anti-dinitrophenyl antibody titer and affinity and in vitro by mitotic responsiveness to phytohemagglutinin, concanavalin A and lipopolysaccharide. Anti-body titer and affinity as well as the response to T lectins were found to be increased in chimeras. These results were attributed to increased function of mature T2 cells, which could explain the reduced incidence of reticulum cell sarcoma in chimeras.

Animals↗
PubMed1976

Biological effects of Escherichia coli lipopolysaccharide (LPS) in vivo. II. Selection in the mouse thymus of PHA- and con A-responsive cells.

The effect of LPS injection on mouse thymocytes was examined by in vitro stimulation with PHA and Con A. Thymocytes from LPS treated mice were found more responsive than normal thymocytes to PHA and Con A. The increase of responsiveness was different for PHA and Con A, and dependent on the dose of LPS injected. This dose dependency suggests that LPS in vivo modifies the thymocyte population by progressively eliminating T1 cells and selecting T2 cells. These effects seem to be mediated by corticosteroids because they were prevented by adrenalectomy, a finding in agreement with the notion that the injection of cortisone induces similar cell changes in the thymus.

Adrenalectomy↗