Effect of thymectomy on induction of immunologic tolerance in the effectors of delayed hypersensitivity]

The influence of thymectomy (Tx) on induction of tolerance of delayed type hypersensitivity effectors (DHE) was examined. Tx did not interfere with induction of tolerance to sheep red blood cells (SRBC) achieved with combined injections of the massive dose of the antigen and cyclophosphamide (Cy). Tx resulted in prolongation of unresponsiveness. The injection of mice with the massive dose of SRBC alone also resulted in tolerance formation. However, this type of tolghtly depressed formation of DHE in intact but not in Cy treated mice. The results obtained are in agreement with the idea of the existence of diverse mechanisms of tolerance induction (clonic-deficient and suppressor). These data also suggest the existence of two subpopulations differing in susceptibility to Cy and Tx in DHE effectors and their precursors.     

The regulatory effects of cytokines on the induction of a peripheral immunologic tolerance in mice.

Previous reports have demonstrated that injection of rIL-1 alpha into mice abrogates the ability of deaggregated human gamma-globulin (HGG) to induce a state of antigen specific immunologic tolerance in vivo. Our results demonstrate that human rIL-1 beta and a bioactive nonapeptide of human IL-1 beta inhibit the induction of tolerance to HGG suggesting that IL-1 affects tolerance induction through a noninflammatory mechanism of action because the immunoactive nonapeptide possesses only immunomodulatory properties. Further, TNF-alpha but not IL-6, cytokines with many bioactivities in common with IL-1, was found to inhibit the induction of tolerance. Therefore, it appears unlikely that IL-6 plays a role in the pathway by which either IL-1 or TNF-alpha interferes with tolerance induction. Although IL-2, IL-4, and IFN-gamma were incapable of directly affecting the induction of tolerance to HGG, it was determined that IL-4 and IFN-gamma were capable of inhibiting the ability of IL-1 to abrogate tolerance induction. It has been suggested that IL-1 induces the generation of endogenous IL-1 in vivo. Further, it has been demonstrated that IFN-gamma as well as IL-4 inhibits the synthesis of IL-1. Inasmuch as IL-4 and IFN-gamma inhibit the ability of IL-1 to abrogate tolerance induction, it appears that it is the endogenously generated IL-1 that interferes with tolerance induction. It was also determined that neither IL-4 nor IFN-gamma inhibits the activity of IL-1 which is consistent with results reported by others. Thus, results presented here suggest that the inhibition of tolerance induction to HGG by IL-1 may involve the stimulation of endogenous IL-1 synthesis.     

The effect of allogeneic spleen cells on the induction of immunologic tolerance

It is shown, in this study, that the transfer of parental immunocompetent spleen cells to F₁ hybrid mice interferes with the induction of tolerance to human gamma globulin (HGG) in the F₁ recipients. The transfer of syngeneic spleen cells did not cause this interference, but the transfer of HGG-tolerant parental spleen cells was as effective as that of their normal counterparts. Hence, the interference with tolerance induction was attributed to the histoincompatibility of donor and host cells and, more specifically, to the graft-vs-host reaction. A mechanism of interference with the expression of tolerance by an antigen-specific T-cell bypass is discussed.     

Effect of thyroidectomy on the growth of the adult rat and on weight recovery after fasting]

After thyroidectomy, the growth of adult male rats is almost completely arrested. Body weight regulation is still present, but its decreased: actually, after fasting, thyroidectomized animals do not increase their daily food intake.     

Effect of aging on T-cell tolerance induction

In the MHC compatible rat strain combination AS → HS, the same ⁵¹Cr-labeled lymph node suspension behaves totally differently depending on whether it is injected into syngeneic or allogeneic recipients. Using ⁵¹Cr-labeled lymph node suspensions from AS or (AS × HS)F1 donors, and AS, HS, and F₁ hosts, the distribution of label over a 72-hr period was studied. Evidence has been obtained that recognition of self-components results in the homing of cells to the lymph nodes in syngeneic hosts, while recognition of foreignness impairs homing of the same cells to the lymph nodes in allogeneic hosts. The spleen is the major organ in which these recognition processes occur. Substantially more cells are destroyed by nonimmune allogeneic hosts than by syngeneic hosts, a clear difference being apparent as early as 6 hr after injection. Some lymphoid cells are obligatory spleen seekers and do not enter the lymph nodes.     

Suppression of IgE antibody production in SJL mice. V. Effect of irradiation and adult thymectomy on the suppression of IgE antibody production in SJL mice

Anti-DNP IgE antibody production was low and transient in SJL mice which were immunized with 1 microgram DNP-Nb and 1 mg A1(OH)3. The immunized SJL mice were irradiated (60-540 R) 1 day after challenge. A dose higher than 180 R induced enhancement of anti-DNP IgE antibody production as compared to nonirradiated control mice, suggesting the existence of irradiation-sensitive suppressor cells. Anti-DNP IgE antibody production was suppressed when immunized and irradiated SJL mice were injected with spleen cells from adult-thymectomized SJL mice. The donors of the spleen cells were thymectomized 2 or 4 months previously, and this suggests that the suppressor cells from unprimed mice are long-living T cells.     

Effect of antibiotics on indices of immunologic reactivity in mice

The effect of ristomycin, chloramphenicol, kanamycin, benzylpenicillin, streptomycin, and cephaloridine on the indices of cellular and humoral immunity was studied comparatively on intact animals and on animals with secondary immune deficiency. The study of the antibiotic effect on the count of rosette-forming lymphocytes (RFL) and the total count of lymphocytes showed that all the antibiotics except streptomycin induced a significant decrease in the count of RFL. The most active was kanamycin. It lowered the count of RFL 5-fold as compared to the control. The total count of lymphocytes was lowered after administration of ristomycin, chloramphenicol and kanamycin. In the animals with immune deficiency induced by cyclophosphamide benzylpenicillin potentiated the inhibitory effect of cyclophosphamide on the weight of the lymphoid organs, while streptomycin lowered the effect of cyclophosphamide. No such effect was observed with the use of the other antibiotics. The data indicated the necessity of taking into account the effect of various antibiotics on the immune system, especially under conditions of immune deficiency.     

Good tolerance and absence of immunologic effects in mice treated with arsenic-rich thermal water

Three strains of mice were given, per os and ad libitum, a spa water containing 6.8 mg/l arsenic and indicated for the treatment of allergic respiratory diseases or chronic bronchitis. The daily arsenic intake was approximately from 1.5 to 4 mg/kg. No effect on body weight gain or on the various immune parameters assessed was observed. These results demonstrate that this spa water, despite its high arsenic content, is not toxic and does not interfere with the immune system of healthy mice.