Autostimulatory lymphoid cells in aging mice: induction of syngeneic host-versus-graft reaction by radioresistant adherent cells in normal recipients

When young (6-week-old) BALB/c and also young C57BL/6 mice were inoculated into footpads with spleen cells from normal, syngeneic, aged donors, their response to the inoculum resulted in the enlargement of popliteal lymph nodes (PLN). The degree of PLN enlargement increased as the age of donor mice increased up to age one year. Spleen and lymph node cell populations were highly effective in eliciting the PLN enlargement. Thymus cells and bone marrow cells were moderately effective, but erythrocytes were ineffective. Resident peritoneal exudate cells and spleen adherent cells were much more effective than a whole spleen cell population. The syngeneic response seems to be attributable to a host-versus-graft reaction, since the PLN response was not affected by 2000 rad irradiation of inoculum cells and since the nylon wool-passed spleen T cell population was ineffective as the stimulator. The response was significantly reduced 3 weeks after thymectomy of recipients. PLN enlargement was also observed in older (7-month-old) mice which received spleen cells of younger mice. In this case, however, the response is ascribable to a graft-versus-host reaction, since the inoculation of radiosensitive spleen T cells into footpads resulted in the PLN enlargement. On the other hand, such a stimulatory activity was not found in either lymph node cells or thymus cells. These results suggest that the antigenicity of adherent cells changes with age and that the change is discernible by spleen-locating and short-lived T cells of young mice.

Ontogeny of antigen-presenting activity of haptenized cells in mice: early development of syngeneic T cell-stimulatory cells in thymus

Trinitrophenyl (TNP)-modified thymus cells stimulated the proliferation of syngeneic spleen T cells in in-vitro culture supplemented with syngeneic normal mouse serum. The stimulatory activity of the TNP-adult thymus cells was about a half of that of TNP-adult spleen cells. Neither thymus cells depleted of adherent cells before haptenization nor TNP-thymus cells treated with anti-Ia antiserum served as stimulators. TNP-thymus cells, but not TNP-spleen cells, prepared from cells of newborn mice within one week after birth were almost as competent as adult TNP-thymus cells. TNP-spleen cells first became effective when spleen cells were obtained from mice at the age of 3 weeks. Ineffectiveness of the newborn spleen cells is not due to immunosuppressive function. These results indicate that Ia-bearing antigen-presenting cells appear earlier in the thymus than in the spleen. The intrathymic Ia+ adherent cells, however, seem not to be autonomously potent for accessory cell function, since haptenized thymus cells were not able to stimulate T cells if adherent cells were removed from the responder cells. This suggests that the second type of adherent cells residing in spleen but not in thymus is required for the activation of T cells in response to TNP-thymic adherent cells.

The use of phagocytic peritoneal exudate cells as targets for the estimation of cytotoxic T cell activity

A new method for measuring cytotoxic T lymphocyte (CTL) activity has been developed with peritoneal exudate cells (PECs) as target. A monolayer of target PECs was labelled with Indian ink and exposed to CTL. After incubation, detached or damaged PECs were rinsed out of the target monolayer, and the remaining phagocytes were fragmented and dissolved by the addition of 2 N NaOH. The number of undamaged target cells was estimated by colorimetric reading of the amount of Indian ink in the phagocytes surviving CTL attack. In studies with several strains of mice, only PECs from the same strain as the stimulator cell donors used for CTL induction were damaged by CTL effectors. When CTLs generated against TNP-modified syngeneic stimulators were used as effectors TNP syngeneic PECs, but neither unmodified syngeneic PECs nor allogeneic TNP-PECs, were damaged. These results demonstrate the antigen specificity of immunolysis of PECs. Macrophage target cells were stable and showed no tendency to spontaneous cell damage during 24 h incubation without effector cells.

Plasmid-controlled mercury biotransformation by Clostridium cochlearium T-2

A strain of Clostridium cochlearium having methylmercury-decomposing ability was isolated. The ability was cured by the treatment with acridine dye and recovered by the conjugation of the cured strain with the parent strain. The cured strain then showed the activity to methylate mercuric ion as previously reported (M. Yamada and K. Tonomura, J. Ferment. Technol. 50:159-166, 1971). These results and the agarose gel electrophoretic pattern of the deoxyribonucleic acids from the lysates indicate a possible role of plasmids in controlling the mercury biotransformation of the two opposite directions in a single bacterial strain: methylation in the absence of the plasmid and demethylation in the presence of it. A possible mechanism for mercury resistance involving hydrogen sulfide is discussed.

Studies on the resistance to tolerance induction against human IgG in DDD mice. II. Tolerogen-resistant T-cell population in the spleen

Further studies were carried out to investigate cellular sites of the resistance to the induction of immunological tolerance to HGG in DDD mice, assuming the presence of a subset of tolerogen-resistant splenic T cells. Spleen-seeking T cells were shown to be relatively resistant in comparison with lymph node-seeking T cells. The existence of a tolerogen-resistant T-cell subpopulation was indicated from the experiments demonstrating that tolerance was easily attained after adult thymectomy and that lymph node T cells became much more resistant to tolerance induction after adult splenectomy. The latter experimental result might also exclude the possibility of differences in microenvironment (probably in A cells) between spleen and lymph node. An attempt was made to investigate a possible involvement of A cells in the induction of tolerance. A cells were deprived in vivo by irradiation of the host 3 days prior to spleen cell transfer and in vitro by passing a spleen cell suspension through a Sephadox G-10 column. The deprivation of A cells resulted in priming of the host by the tolerogen rather than easier tolerance induction. No suppressive activity was observed in lymph node cells from tolerized mice. These results suggest that there exists a set of T cells, generated relatively recently in the thymus, preferentially migrating into spleen and there becoming resistant to tolerance induction.

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.

Tolerance induction as an index of age-related changes

Tolerance to rabbit gamma globulin RGG) can be induced in newborn or three week old mice of all strains tested. In six week old SJL or NZB mice there is marked resistance against tolerance induction to RGG. This resistance increases with increasing age and is completed by the age of 12 weeks. Resistance to tolerance can be observed in 3 week old SJL animals when human IgG3 but not when human IgG1 or RGG is employed as tolerogen. Using IgG3, resistance to tolerance induction can be demonstrated in 28-34 week old A/J, C57BL/6J and DBA1/J mice. Thus resistance to tolerance induction seems to be a concomitant of aging; SJL and NZB differ from other strains only by the age at which this change is apparent. By the 6th week of age, SJL and NZB mice develop marked resistance to tolerance induction with RGG, and so do hybrids between these two strains; there is no complementation with respect to resistance against tolerance induction. Aggregate-freed iodinated rabbit gamma globulin (125I-RGG) but not mouse immunoglobulin is eliminated much more rapidly from the body of normal 6 week old SJL and NZB mice than from the body of hybrids. Complementation in the hybrids might occur and prevent a response to small quantities of aggregate-freed RGG.