Suppressor cells and their precursors in A/J mice, tolerant to heterologous gamma globulin

Developmental change in the second half of life--strategies for modification of selected compartments of aging

Age-related changes of different individuals multicentric and polymorphic. We have approached this problem of age-related changes by examining (1) membrane densities of receptors of various ligands in different organs, and (2) changes in different classes of T cells and of antibody response. Three strategies have been developed to modify progression of age-related changes to different extents in different compartments in which age-related changes occur. The first is based on administration of hormones, the second on administration of purine analogues and the third on administration of diets which differ in fatty acid content. Details of this last approach are reviewed in this paper. Lifespan of different species is a component of the evolution of each species. The variables which are decisive in the evolutionary processes which affect lifespans of different species are not necessarily variables which play a decisive role in the different health span of different individuals of the same species. For each individual of a given species, relative health span represents variations within the limits of the evolved lifespan of the species and depends on alleles of many different genes.

Sensitization of T and B cells by a normally tolerogenic macromolecule: the induction of unresponsiveness and of sensitization is polymorphic

Changes induced in B and T cells by tolerogen were experimentally defined in animals which resist down-regulation. Female A/J, C57BL/6J, MLR/MpJ-lpr/lpr, MLR/MpJ-+/+ and NZB/B1NJ mice were injected at various ages with a tolerogenic form of rabbit gamma globulin (sRGG) or were left uninjected, and all were then immunized with dinitrophenylated RGG (DNP-RGG) on alum. The degree of tolerance was estimated by measuring anti-DNP and anti-RGG spleen plaque-forming cell (PFC) numbers. In some cases, the state of T or B cells deduced from these experiments was further examined by cell transfer experiments. Four types of responsiveness to the tolerogenic form of RGG (sRGG) were distinguished: 1) persistent tolerance inducibility of T and B cells to tolerance induction (A/J); 2) T cells retaining tolerance-inducibility after initiation of age-dependent sensitization of B cells by the tolerogenic form of RGG (C57BL/6J, NZB/B1NJ); 3) age-dependent resistance of T cells to tolerance-induction and age-dependent sensitization of B cells by tolerogen, with the sensitization only manifesting itself in reactivity with T cells from immunized donors (SJL/J); and 4) sensitization of T cells by a usually tolerogenic form of RGG (MLR/MpJ-lpr-lpr). Thus, the development of resistance against tolerance induction is highly polymorphic, not only with respect to the age of onset, but also with respect to the cellular site of its first manifestation and the effect. Possible mechanisms of B-cell sensitization in sRGG-treated C57BL/6 and NZB mice are discussed in relation to the age-dependent emergence of a B-cell subpopulation and of non-specific helper T-cell factors.

Aging and the immune system

Information is presented on changes in the aging immune system. An analysis of separate streams of cellular aging in the inbred mouse is presented. It is demonstrated that there is extensive polymorphism in the aging of different types of executive and regulatory cell lines.

Polymorphism of T- and B-cell sensitization by aggregate-freed heterologous gamma-globulin

Female A/J, C57BL/6J, SJL/J, MRL/MpJ-+/+, MRL/MpJ-lpr/lpr, NZB/BINJ and male BXSB/MpJ mice were injected at various ages with a tolerogenic form of rabbit gamma-globulin, or were left untreated and all were then immunized with dinitrophenylated rabbit gamma-globulin. We could distinguish 4 types of responsiveness to sRGG: (1) persistent T-cell tolerance (A/J, MRL/MpJ-+/+); (2) persistent T-cell tolerance and age-dependent resistance and sensitization of B-cells to tolerance induction (C57BL/6J, NZB/BINJ); (3) decreasing T- and B-cell tolerance (SJL/J, male BXSB/MpJ); and (4) T-cell sensitization in older animals (MRL/MpJ-lpr/lpr). Suppressor capacity and its regeneration was examined in terms of colchicine and cyclophosphamide treatment. Colchicine increased the immune response to a much greater extent in 10-week-old than in 6-week-old MRL/MpJ-lpr/lpr mice and had little effect on MRL/MpJ-+/+ mice. It had a relatively small effect on 15-week-old NZB/B1NJ and a much greater effect on 6-week-old animals. The reason for these differences are discussed.

Sensitized spleen B-cells in tolerance-resisting SJL mice

A subpopulation of B-cells becomes sensitized in the 15-week-old SJL mouse, exposed to aggregate-freed rabbit gamma-globulin, which is highly tolerogenic when given to younger animals. This state of activation can only be expressed in collaboration with sensitized T-cells. The sensitized B-cell does not play an important role in the response of the intact 15-week-old SJL mouse, since there are no sensitized T-cells in the sRGG-treated animals.

Accelerated development of a Th-2 type factor in animals with and without an imbalance between help and suppression

A helper factor can be detected in antigen-treated supernatants from spleen T and adherent cells of sensitized animals. This factor promotes an indirect hapten-specific plaque forming response of B cells, irrespective of the identity of the carrier, i.e. provides the Th-2 type of help. Factor production increases with age and occurs most rapidly in strains known to have an accelerated decrease of suppressor capacity. The reason for the inverse correlation between suppressor capacity and the Th-2 type of helper factor is discussed.

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 ae. 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 loss 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.

The thymus as primary site for antigen-specific T suppressor cells in neonatally induced tolerance to bovine serum albumin

The ontogeny of antigen-specific T suppressor cells in thymus and spleen was analyzed in CBA/Ca mice which were rendered tolerant as neonates by subimmunogenic doses of bovine serum albumin (low-zone tolerance). Activity of T suppressor cells from those mice was assessed by an assay in which spleen cells from animals primed with fluorescein-conjugated human gamma globulin can be stimulated in vitro to produce IgG anti-fluorescein antibodies when cultured in the presence of fluorescein-conjugated bovine serum albumin. Carrier-specific T suppressor cells appear first in the thymus (day 10), and much later (day 30) in the spleen. The data are discussed in connection with the possible role of T suppressor cells during induction of tolerance in newborn mice.

The effect of ribavirin and rifamycin SV on age-dependent changes of the immune system during the adult life of SJL mice

Ribavirin and Rifamycin SV, given from birth to adult life, arrest the loss of suppressor capacity, normally occurring in older SJL mice. The two drugs differ in their effect on Th-2-type help for the indirect plaque-forming response, i.e. for help which is independent of the carrier-hapten bridge. This type of help normally increases with age. Ribavirin treatment inhibits development of Th-2-type of help; Rifamycin SV does not interfere with the development of this type of help. Neither of the two drugs had an effect on the ability of SJL mice, not treated with aggregate-freed RGG, to make a plaque-forming response to aggregated RGG.