B. Cinader

Dietary fat alters the fatty acid composition of lymphocyte membranes and the rate at which suppressor capacity is lost

SJL/J mice were fed from conception two nutritionally adequate semi-purified diets that differed only in polyunsaturated to saturated fatty acid content. The effect of diet fat on the fatty acid composition of membranes from spleen and thymus cells was determined. Diet fat was found to significantly alter the fatty acid composition of lymphocyte membrane phosphatidylcholine and phosphatidylethanolamine. Diet also altered the degree of resistance against tolerance-induction.

A membrane antigen of rabbit thymus cells

Abstract Rabbit cells, bearing a thymus-specific antigen, which we call rabbit thymus lymphocyte antigen (RTLA), could be detected with a suitably absorbed heterologous antiserum (goat). In the presence of complement, the RTLA antiserum lysed more than 95% of thymus cells, 70 ± 6% of lymph node cells, 46 ± 10% of spleen cells and 12 ± 7% of bone marrow cells. The number of direct or indirect hemolytic spleen plaques was not reduced by treatment with RTLA antiserum and complement, but was greatly diminished by an unabsorbed thymus antiserum which killed more than 90% of bone marrow cells. RTLA-bearing subpopulations of spleen cells were characterized by velocity sedimentation analysis and were distinguished from Ig receptor bearing subpopulations. The antiserum concentration could be so adjusted that the cytotoxicity against bone marrow was not manifested, while the cytotoxicity against other cell populations remained unchanged. The latter were identified by thymidine incorporation induced by treatment with antibody directed against rabbit light chain allotype. A small subpopulation of thymus cells did not have RTLA antigen and sedimented with a velocity distinct from that of the peak of RTLA-bearing cells.

Cellular aspects of tolerance. IV. Strain variations of tolerance induceability.

Abstract The antibody response to RGG of 8-wk old mice of various strains was assessed in terms of half-lives ( T 1 2 ) of lightly iodinated rabbit gamma globulin ( 131 I-RGG) elimination. T 1 2 was increased if the small aggregate content in 131 I-RGG was reduced. The effect of aggregates was least in AKR, largest in Balb/c and SJL and intermediate in the majority of strains, typified by A mice. Differences between various strains, in the degree of tolerance to aggregate freed RGG (centrifuged at 123,000 g ), were observed. The level of residual responsiveness was greatest in SJL mice. More profound tolerance could be induced with biofiltered RGG. Resistance of SJL mice to tolerance induction was also observed when human gamma globulin (HGG) and bovine serum albumin served as tolerogen. Tolerance to RGG and sheep red cells was induced in cyclophosphamide-treated SJL animals.

Cellular aspects of tolerance: I. Parameters of tolerance induction in T cells of spleen and thymus☆

Abstract Unresponsiveness of T cells in thymus and spleen of tolerant animals was determined by reconstitution of lethally irradiated recipients. The degree of responsiveness of these animals was assessed by antigen elimination and two types of plaque assays (liquid and agar) with different sensitivity. Unresponsiveness occurred more rapidly in T spleen cells than in thymus cells. Unresponsiveness of T cells could be induced in the spleens of thymectomized animals and in T cell repopulated thymectomized lethally irradiated recipients. Induction of unresponsiveness did not depend on proliferating bone marrow cells or on accessory cells.

Functional Competence of Dendritic Cells of Ageing C57BL/6 Mice

Highly poly morphic age‐dependent differences in progression of T and B cells have been found in various strains of inbred mice. In the immune system of C57BL/6 mice these occur first in B cells and, later in life, in T cells. In this paper, we have examined the progression in the functional capacity of C57BL/6 dendritic cells (DC). Age‐dependent changes were found in the syngeneic mixed leucocyte reaction, in which the stimulatory capacity of DC increased with age. This increase was independent of the age of the donor of the serum that was added to the culture, and occurred when young donors provided the T cells. Age‐dependent changes in DC properties were not detected in terms of direct plaque‐forming response, response to con‐canavalin A, or in the allogeneic mixed leucocyte reaction.

Mitogen Stimulation of Rabbit Spleen Cells before and after Complement-Mediated Cell Kill with an Antiserum Directed against the Thymus Antigen RTLA

Rabbit thymus lymphocyte antigen (RTLA) has been previously characterized as an antigen of rabbit thymus-derived cells (Cell. Immunol . 7: 484–501, 1973). It has now been shown that

Resistance to Tolerance Induction and Age-Dependent Cellular Changes in SJL Mice

SJL mice became resistant to tolerance induction between the 2nd and 6th week of life. The effect on tolerance induction of radioresistant accessory (A) cells does not depend on the age of the donor, i.e. is the same whether the A-cell donor is 3 or 12 weeks old. In the thymectomized recipient, reconstituted with spleen cells of 12-week-old donors, resistance to tolerance is greater than in the corresponding intact animal. Resistance to tolerance is due to a change in the T cells, occurs at a different rate in the T cells of thymus and spleen, and my be due to change in the relative proportion of different T-cell subpopulations.

Cellular aspects of tolerance: V. The in vivo cooperative role of acceessory and thymus derived cells in responsiveness and unresponsiveness of SJL mice

Abstract Adult (8-week-old) SJL mice reach a relatively low degree of tolerance when injected with aggregate free rabbit γ-globulin (RGG). To analyze this phenomenon, we first examined indirect plaque-forming responses (PFC) in terms of participation of accessory and thymus-derived cells. Double transfer experiments were used; accessory cells were removed from donor cells by filtration over glasswool and their capacity reduced in recipients by 3 day preirradiation or by horse erythrocyte-mediated blockage. Using this type of experimental arrangement we found that the antibody response to RGG required the cooperation of accessory and thymus-derived cells. The induction of tolerance was affected by the presence of accessory cells. Preirradiated secondary recipients were reconstituted with spleen cells from accessory cell-deprived donors which had received thymus and bone marrow cells. In some experiments, the thymus and bone marrow cells were passed over glasswool. The primary recipients were left untreated or were given tolerogen. A more profound state of tolerance (reduction in plaque forming response) was the consequence of the incapacitation or removal of accessory cells. The magnitude of the reduction in PFC was directly related to the completeness of accessory cell removal and incapacitation. Responsiveness could be restored by administration of irradiated spleen cells as a source of accessory cells. The need for thymus-derived (T) cells in the antibody response was demonstrated by double transfer experiments in which the primary recipient was restored with thymus cells alone, bone marrow cells alone, or with a mixture of cell types.

Effects of aging on neuronal electrical membrane properties

The electric membrane properties (EMP) of dorsal root ganglion (DRG) neurons in cell cultures prepared from control mice (8-14 weeks) and old mice (90-92 weeks) were compared. The old neurons had a number of significant alterations in EMP compared to controls including decreased electrical excitability, increased action potential duration and more pronounced biphasicity of the repolarization phase. The old neurons also had larger action potential overshoot and afterhyperpolarization. The pattern of altered electric membrane properties was consistent with an age-induced shift from voltage-sensitive sodium channels to less excitable voltage-sensitive calcium channels and also a decrease in potassium permeability during the repolarizing phase of the action potential.

Mechanisms involved in age-dependent decline of immune responsiveness and apparent resistance against tolerance induction in c57bl/6 mice.

The plaque‐forming antibody response of C57BL/6 mice to rabbit gamma globulin (RGG) decreases as a function of age. RGG in tolerogenic form induces tolerance of young mice but sensitizes older animals. If antigen is administered together with lipopolysaccharide, the age‐dependent decline in immune responsiveness is not observed, nor are older animals sensitized by tolerogen. The age‐dependent decline in immune responsiveness is due to a less of T helper capacity; sensitization by tolerogen is attributable to a subpopulation of B cells which becomes sensitized by the tolerogen. Older animals, treated with tolerogen, show a degree of central tolerance of T cells and a relatively slight, age‐dependent diminution in colchicine‐ or cyclophosphamide‐sensitive precursors of suppressor cells.