Hydrocortisone and inhibitors of prostaglandin synthesis. Potentiation of allograft survival in mice

We studied the effects on survival of allogeneic skin grafts after treatment with hydrocortisone and/or inhibitors of prostaglandin synthesis: indomethacin and flufenamate. We found a marked synergistic effect of combined treatment with hydrocortisone and indomethacin or flufenamate. Neither hydrocortisone nor indomethacin or flufenamate, when given alone in relatively small doses, caused delayed graft rejection. However, when small doses of hydrocortisone were used in combination with flufenamate or indomethacin, the median survival time (MST) of allogeneic grafts was prolonged from 11.4 days to 20.9 and 23.8 days, respectively. Moreover, the increase in graft survival was comparable to that obtained by treatment with relatively high doses of azathioprine alone or combined with hydrocortisone. The finding of synergism between low doses of prostaglandin synthesis inhibitors and glucocorticoids in delaying graft rejection suggests that such treatment might provide a relatively safer means of achieving clinical immunosuppression than the high doses of steroids and azathioprine currently in use.

Genetic control of autoimmune encephalomyelitis and recognition of the critical nonapeptide moiety of myelin basic protein in guinea pigs are exerted through interaction of lymphocytes and macrophages

Genetic control has been studied of the response to the encephalitogenic nonapeptide (NP) determinant of myelin basic protein (BP) in inbred guinea pigs of strains resistant or susceptible to induction of experimental autoimmune encephalomyelitis (EAE). By studying bone marrow-reconstituted animals, we found that susceptibility to induction of EAE was a function of the genotype of the cells of the lymphohematopoietic system and not of the physiological environment or target organ. Analysis of the T cell response showed that susceptible strains 13 or (2 X 13)F1 hybrid guinea pigs recognized the NP determinant when injected with whole BP in adjuvant. Resistant strain 2 guinea pigs responded to undefined determinants on BP, but not to the NP moiety. We investigated the cells involved in regulating the response to the NP determinant by injecting susceptible F1 hybrids with BP-pulse macrophages of either parental strain. Susceptible strain 13 macrophages triggered a response to the NP determinant and induced clinical EAE. In contrast, F1 animals injected with resistant strain 2 macrophages failed to respond to the NP determinant, although the macrophages were capable of presenting other undefined determinants present on whole BP. Therefore, genetic control of the immune response to the NP determinant appears to be exerted at the level of antigen presentation by macrophages to T lymphocytes.

The rapid isolation of clonable antigen-specific T lymphocyte lines capable of mediating autoimmune encephalomyelitis

The isolation and propagation of functional antigen-specific lines of T lymphoblasts is described. These lines were found to recognize foreign or self antigens in association with accessory cells of syngeneic major histocompatibility complex genotype. Intravenous inoculation of a T cell reactive only against myelin basic protein led to development of clinical paralysis in syngeneic rats. Thus, it is possible to study biological function as well as antigen specificity using T cell lines.

Influence of corticosterone on the response to gonadotropin-releasing hormone in rats

The objective of this study was to determine whether the diurnal rhythm of corticosterone (B) alters the response of the pituitary to gonadotropin-releasing hormone (GnRH). Mature female rats housed in constant illumination were ovariectomized (Ovx) and adrenalectomized (Adx), and maintained on either corticosterone (B, 260 micrograms/ml in drinking water) or 0.9% saline. 3 weeks later a silastic implant of estradiol (E2) was implanted subcutaneously into each animal. For the next 5 days B-maintained rats received a daily injection of either B (250 micrograms/100 g BW) or vehicle at 05.00 or 17.00 h. Groups of rats were sacrificed at 0, 1, 3, 6, 12 and 18 h after the fifth injection, and plasma B and E2 were measured. Other animals were challenged with GnRH (1.0 ng/100 g BW) at 0, 6, 12 and 18 h after the last B injection. The fifth B injection initiated changes in plasma B which closely mimicked the normal B rhythm in intact rats. E2 levels (approximately 100 pg/ml) remained fairly constant over the same period. In rats receiving B injection at 17.00 h, the response to GnRH was altered by B administration. The LH response was greatest 6 h after B was injected, and animals showed a lower response at other times. The same relationship between circulating B and the response to GnRH could not be demonstrated in rats injected with B at 05.00 h. Animals maintained on saline exhibited higher basal LH levels, a longer mean half-life of LH, and the plasma LH response to GnRH was lower than in animals receiving B therapy. These results indicated that: (1) physiological dosages of B can alter the response to GnRH in constant light rats; (2) B has a potentiating effect on this response, and (3) B may also influence the clearance rate for LH.

Spontaneous remission of autoimmune encephalomyelitis is inhibited by splenectomy, thymectomy or ageing

Experimental autoimmune encephalomyelitis (EAE) can be induced in genetically susceptible animals by injecting them with basic protein of myelin (BP) in a suitable adjuvant. EAE in adult Lewis rats is expressed clinically by acute paralysis and histologically by mononuclear cell infiltration of the central nervous system. Most rats spontaneously recover from EAE and show little or no damage to myelin. We report here that chronic progressive EAE with marked myelin lesions can be induced by a single injection of BP in complete Freund's adjuvant in intact 13-month old rats, or in 4-month old rats provided they have been splenectomized. Juvenile 2 1/2-month old rats recover spontaneously despite splenectomy. Thymectomy of young adult rats leads to relapsing EAE. These results illustrate that the clinical course of EAE is markedly influenced by age and integrity of immune organs. Furthermore, they provide an experimental model with features similar to those of chronic relapsing disease of the nervous system of man.

H-2K mutation controls immune response phenotype of autoimmune thyroiditis. Critical expression of mutant gene product in both thymus and thyroid glands

Autoimmune thyroiditis (EAT) can be induced by immunizing mice against mouse thyroglobulin. A gene critical to the phenotypical expression of EAT was mapped to the H-2K locus by studying B6 mice and its mutant strain B6.H-2ba. To identify organs in which expression of the gene was decisive for the EAT phenotype, we transplanted thyroid or irradiated thymus glands into various strains of normal mice or thymusless nude mice. We found that the pathophysiology of EAT was controlled by the expression of specific H-2 genes in both the target thyroid gland and the thymus gland.

Immunospecific depletion of lymphocytes rejecting skin allografts using sensitized syngeneic initiator T lymphocytes

Experiments were done to prolong the survival of transplanted allogeneic skin in mice. We used the recruitment model of cell-mediated immunity to remove effector lymphocytes of recipients specifically directed against foreign antigens of the skin graft donor. BALB/c recipient mice were inoculated in both footpads with syngeneic initiator T lymphocytes (ITLs) sensitized against C57BL/6 fibroblasts. At the height of the recruitment response, the reacting popliteal lymph nodes (PLNs), containing specific anti-C57BL/6 effector lymphocytes, were surgically excised. The mice were then engrafted with skin from C57BL/6 mice or third-party C3H/eB mice. We found that selective treatment of the recipient significantly prolonged the mean survival time of the antigen-specific C57BL/6 grafts from 11.9 to 22.1 days. These findings show that physiological immunosuppression can be achieved, without any harmful or toxic side effects, by sequestration of the recipient's specific lymphocytes.

H-2 gene products influence susceptibility of target thyroid gland to damage in experimental autoimmune thyroiditis

The restriction of the pathogenesis of experimental autoimmune thyroiditis (EAT) by H-2 gene products was investigated. EAT was induced by injecting thyroglobulin extract plus adjuvant into F1 hybrid mice that had been implanted under the kidney capsules with thyroid glands originating from either the EAT-susceptible or -resistant parental strain mice. We found relative H-2 restriction of thyroid damage to those glands originating from the H-2 susceptible parental strain. H-2 restriction of damage at the level of the target thyroid gland implicates cytotoxic effector T lymphocytes as a pathogenic agent of EAT.

Immunospecific depletion of graft-versus-host-reactive lymphocytes using sensitized syngeneic initiator T lymphocytes

We investigated a model of a lethal graft-versus-host (GVH) reaction with the aim of depleting donor spleen cells of immunospecific GVH-reactive lymphocytes. In previous studies of the recruitment of effector T lymphocytes by sensitized syngeneic initiator T lymphocytes (ITLs) we found, using a local GVH reaction, that precursors of specific GVH-reactive lymphocytes were recruited to a draining lymph node. In this study, adult F1 hybrid mice were lethally irradiated and reconstituted with 2 x 10(6) syngeneic bone marrow cells and varying numbers of spleen cells from parental strain mice. To deplete donor spleen cells of GVH-reactive lymphocytes, parental strain mice were given injections in the hind footpads 6 days earlier of syngeneic ITLs that had been sensitized in vitro against allogeneic fibroblasts. We found that injection of ITLs sensitized against the relevant allogeneic antigens led to a marked decrease in the specific GVH potential of donor spleen cells. These findings show that GVH-reactive lymphocytes can be depleted selectively by activating their recruitment to particular lymph nodes, using syngeneic ITLs.

Immune response genes have a variable influence on the selection of antigenic foreign and self determinants of insulin

We studied the proliferative response of mouse T lymphocytes to determinants on ungulate insulins. The immunopotency of defined determinants on the molecule was found to be regulated by three factors: the immune response genes of the immunized mouse, the mode of presentation of insulin on cells or in adjuvant, and the intramolecular cooperativity between different determinants on the insulin molecule. Autosensitization against self determinants was observed under specific conditions. These findings emphasize the variable expression of immune response genes.

Promoting differences in hospitals

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Should patients have access to their medical records?

Rather than opposing patients' access to their own medical records, physicians can use this trend to deter malpractice actions and improve patient communications. By documenting their observations in writing, noting patient responses, and maintaining honest rapport with the patient and his or her family, physicians can more effectively protect both themselves and their patients in the future.

Sequential interaction of macrophages, initiator T lymphocytes and recruited T lymphocytes in a cell-mediated immune response to soluble antigen

We have investigated the sequential interaction of macrophages, initiator T lymphocytes (ITL) and recruited T lymphocytes (RTL) in the development of a T cell-mediated response to soluble antigens. Macrophages were pulsed with soluble antigens and used to sensitize ITL in vitro. The ITL were irradiated to prevent their proliferation and then injected into the footpads of syngeneic mice. Sensitized ITL were found to recruit immunospecific RTL in the draining lymph nodes, as determined by a thymidine uptake assay of the lymph node cells in vitro. The richest source of lymphocytes with ITL activity was the thymus, and progressively less activity was detectable among spleen or lymph node lymphocytes. The magnitude of the subsequent RTL response could be modified by genetic differences between the ITL and the antigen-pulsed macrophages that were used to sensitize them. Thus, ITL conveyed an immunogenic signal to RTL whose magnitude reflected the genotype of the macrophages, but whose specificity was directed by determinants of the soluble antigen.

Transition from T cell protection to T cell enhancement during tumor growth in an allogeneic host

The cell-mediated immune response of mice toward a lethal allogeneic tumor was investigated during tumor development. The activity of spleen cells from the tumor-bearing mice was studied by transferring them together with 3LL tumor cells into normal C3H/eb recipient mice. The activity depended upon the time interval between inoculation of the tumor and transfer. Spleen cells taken relatively early, 1 week after tumor inoculation, mediated protection against tumor growth. In contrast, spleen cells taken 4 weeks after tumor inoculation markedly enhanced tumor growth. The tumor-enhancing cells, like the tumor-protecting cells, appeared to be T lymphocytes. The enhancing activity could be transferred by extra cellular medium prepared by incubating the enhancing T cells. Protecting activity could not be transferred by cell-free medium prepared from the protecting T cells. Both activities were found to exist to a relatively slight degree in populations of spleen cells from normal mice. The transition from T cell protection to T cell enhancement might be a determining factor in the outcome of the host-tumor relationship.

Suppressor factor secreted by T-lymphocytes from tumor-bearing mice

Spleen cells from C57BL mice bearing the syngeneic carcinoma 3LL enhanced tumor growth. Tumor growth was also enhanced by a soluble factor found in the media of cultured spleen cells from tumor-bearing animals. This factor suppressed a protective immune response of the host and was found to be a product of T-lymphocytes. Removal of B-lymphocytes and macrophages did not prevent its appearance in the culture media, whereas removal of T-lymphocytes inhibited its appearance. Similar suppressor factors were obtained from C3H mice bearing the 3LL tumor and from mice with other tumors. The suppressing factor produced after the growth of 3LL tumor also enhanced the growth of other tumors. It could act on strains incompatible with the donor of the factor-producing cells. Hence tumor growth was possibly facilitated by soluble products of T-lymphocytes that were found in spleens of tumor-bearing mice and that nonspecifically suppressed immune defense mechanisms.

Recruitment of effector lymphocytes by initiator lymphocytes. Circulating lymphocytes are trapped in the reacting lymph node

In previous studies, we have shown that initiator T lymphocytes (ITL) sensitized in vitro recruit effector T lymphocytes in vivo. When ITL were sensitized against fibroblast antigens in vitro and injected into footpads of syngeneic recipients, they induced enlargement of the draining popliteal lymph node (PLN) and the development there of specific effector lymphocytes of recipient origin. To study the basis of this lymph node response in recruitment, we injected 51Cr-labeled spleen cells i.v. into recipients of sensitized ITL and found that the labeled circulating lymphocytes were trapped in the reacting PLN. The trapping depended on surface properties of the labeled circulating lymphocytes, as revealed by various enzymatic treatments. The trapping process was radiosensitive, both on the part of the trapped lymphocytes and the lymph node-trapping mechanism. Thus, sensitized ITL injected into the hind footpads migrate to the PLN and induce the trapping of circulating recruitable lymphocytes, which either differentiate into or regulate the differentiation of effector T lymphocytes.

Recruitment of effector lymphocytes by initiator lymphocytes. Recruited lymphocytes are immunospecific and include graft-versus-host-reactive lymphocytes

We have shown previously that initiator T lymphocytes (ITL), sensitized in vitro against fibroblast antigens, recruit effector T cells in vivo. After injection into hind footpads of syngeneic recipients, sensitized ITL migrated to the draining popliteal lymph nodes (PLN) and activated a trapping mechanism by which circulating lymphocytes were recruited in the PLN. This paper reports experiments designed to test the immunospecificity of these recruited T lymphocytes (RTL). We found that immunospecific RTL were depleted from other lymphoid organs during recruitment in the PLN. However, immunospecific ITL were not depleted from spleens during PLN recruitment. Thus ITL and RTL are functionally distinguishable. We show that specific GVH reactive lymphocytes were also lost from spleens and distal lymph nodes during trapping of RTL in the PLN. Thus, the trapping phase of the recruitment response is immunospecific, as are the sensitization and effector phases. The trapped RTL are antigen-specific, and include the pool of GVH-reactive-lymphocytes committed to the same alloantigen. Thus, it appears that GVH-reactive cells respond to syngeneic ITL sensitized against allogeneic fibroblasts.

Cell-free media of mixed lymphocyte cultures augmenting sensitization in vitro of mouse T lymphocytes against allogeneic fibroblasts

Using an in vitro mouse lymphocyte anti-fibroblast reaction (AFR), we recently reported that the addition of allogeneic stimulator lymphocytes to the sensitization phase of the AFR enhanced sensitization to fibroblast antigens as evidenced by a marked increase in the cytolytic activity of the sensitized lymphocyte population. In the present report we studied the mechanism of this helper effect by testing the capacity of cell-free media derived from 48-h mixed spleen cultures to enhance anti-fibroblast sensitization. We found that such cell-free media could produce a marked helper effect when applied to the sensitization phase of the AFR, but not when added to the cytolytic effector phase. The stimulator cells in the mixed lymphocyte culture (MLC) did not have to be syngeneic with the sensitizing fibroblasts in the AFR in order for the helper effect to be demonstrated. Lymphocytes sensitized to fibroblast antigens in the presence of MLC medium retained their specificity of the effector phase. Our data suggest that the MLC medium acts by enhancing differentiation processes of antigen-triggered lymphocytes. Generation of helper activity by the MLC was abolished by 1000 r irradiation of the responder cells. By using nu/nu and normal spleens, both from two different strains, as cell sources for the MLC, we found that the generation of helper activity depended on T cells capable of proliferation. Furthermore, stimulator lymphocytes differing from responder lymphocytes by non-H-2 alloantigens as well as by point mutation with the H-2 complex were capable of eliciting helper factor(s). Thus, soluble factor(s) produced in a MLC, which are dependent on T lymphocyte proliferation, have the capacity to enhance the sensitization of mouse lymphocytes against antigens present on allogeneic fibroblasts.

Recruitment of effector lymphocytes by initiator lymphocytes. In vivo migration of in vitro sensitized initiator T lymphocytes

We previously found that mouse T lymphocytes sensitized in vitro against allo- or syngeneic fibroblasts, upon injection into syngeneic recipients, do not themselves differentiate into effector cells, but recruit effector T lymphocytes within the draining lymph nodes. As a result of sensitization, these initiator lymphocytes acquire a trypsin-sensitive membrane property which is necessary for recruitment. We now report studies on the in vivo migratory behavior of initiator lymphocytes following sensitization. We injected 51Cr-labeled initiator lymphocytes into recipient footpads and found significantly increased migration of sensitized cells to the draining popliteal lymph node (PLN) during the first day. By amputation of the foot at various times, we showed that migration during the first 12-24 hours was critical for subsequent recruitment. Trypsin treatment of initiator lymphocytes abolished this accelerated migration. Lymphocytes triggered nonspecifically by Con A migrated to the PLN like antigen-sensitized cells. We also compared the migration of injected lymphocytes from the footpad to the PLN in graft-versus-host and host-versus-graft reactions, and found these reactions to differ both from each other and from recruitment in terms of lymphocyte migration. These findings are discussed in terms of the physiology of the cell-mediated immune response and the notion of peripheral sensitization.

Effect of treatment with the methanol extraction residue fraction of killed tubercle bacilli (MER) on the development of spontaneous pulmonary metastases from syngeneic implants of tumor 3LL in C57B1 mice

Treatment of C57B1 mice with the methanol extraction residue fraction of killed tubercle bacilli (MER) shortly before or after surgical removal of a syngeneic implant of lung carcinoma 3LL reduced the incidence of spontaneous, fatally progressing pulmonary metastases in a large number of instances. Under certain conditions, the protective action of MER was pronounced and statistically significant. Small quantities of MER (0.2 mg) were optimally effective, when administered i.p. two days before or one day after excision of the initial implant.

A syngeneic metastatic tumor model in mice: the natural immune response of the host and its manipulation

The cell-mediated immune response against a transplantable syngeneic metastatic solid tumor in mice was studied. The immune reactivity of spleen cells from tumor-bearing mice was found to vary during development of the tumor. For about a week after tumor transplantation, the spleen cells were able to protect recipient mice against challenge with tumor cells. Subsequently, the protective activity was replaced by an enhancing activity. Recipient mice that received tumor cells together with spleen cells from mice bearing tumors for about two or three weeks had a higher incidence of tumor takes and larger tumors than controls. This enhancement of tumor development was correlated with the size of the local tumor or metastases in the donors. The enhancing activity was found to be mediated by T lymphocytes and appeared to suppress the protective immune response of the recipients. We devised a system to strengthen the immune response of the host against the development of tumor metastases. In the tumor model used, removal of the local tumor after s.c. transplantation failed to prevent the development of lung metastases and death in most of the mice. However, syngeneic spleen cells which had been sensitized in vitro against tumor cells were found to serve as immunotherapeutic agents. Injection of such spleen cells into mice from which primary tumor implants had been removed surgically led to a markedly increased survival. Spleen cells from both normal and tumor-sensitized donors were effective, but splenocytes from mice bearing large tumors did not reduce metastatic development after sensitization in vitro. Thus, protection against the development of lethal metastases can be achieved with certain types of lymphocytes sensitized in vitro.

Sensitization of T lymphocytes in vitro by syngeneic macrophages fed with tumor antigens

We investigated the interaction between T lymphocytes and macrophages in the vitro sensitization of lymphocytes against tumor cells. Spleen cells were sensitized in vitro by syngeneic peritoneal macrophages that had been fed with cell-free antigen preparation of syngeneic tumor cells. The sensitized T lymphocytes acquired specific cytotoxic cells. The sensitized T lymphocytes acquired specific cytotoxic activity in vitro and the capacity to inhingeneic fibroblasts, or the antigen preparation by itself were not able to sensitize the lymphocytes against the tumor.

Heterogeneity in the development of cytotoxic T lymphocytes in vitro revealed by sensitivity to hydrocortisone

In the present study we used hydrocortisone (HC) treatment in vivo as a probe to analyze two different in vitro systems for the regeneration of cytotoxic T lymphocyte (CTL), namely the antifibroblast reaction (AFR) and the mixed lymphocyte culture (MLC) system. We found that cells remaining in the thymus after HC treatment had increased reactivity in these two systems. However, the same treatment in the spleen severely depressed the MLC reactivity in both the proliferative and the cytolytic phases, while markedly increasing the AFR reactivity. These findings demonstrate heterogeneity of CTL precursors and/or their pathways of differentiation into effector cells. In addition, MLC-reactive cells in the thymus appear to be distinct from such cells in the spleen, as judged from their differential sensitivity to HC.

Recruitment of effector lymphocytes by initiator lymphocytes: role of a trypsin-sensitive membrane component

In earlier studies we found that initiator T lymphocytes sensitized in vitro against fibroblasts were able to recruit immunospecific effector T lymphocytes in vivo in syngeneic mice. In the present study, to investigate the possible function in effector cell recruitment of sensitizing antigens passively adsorbed onto the initiator cell membrane, we treated the initiator lymphocytes with trypsin. We found that trypsin inhibited recruitment. However, the initiator cells spontaneously recovered their recruiting ability after incubation in vitro for 4 h in the absence of contact with sensitizing antigens. Recovery could be blocked by cycloheximide. Hence, it appears that recruitment depends on the intrinsic metabolic function of the initiator lymphocytes and is not due merely to passively-adsorbed antigen carried over into the recipient mouse.

Immunotherapy of lethal metastases by lymphocytes sensitized against tumor cells in vitro

To learn whether tumor metastases can be prevented by the immune system, we developed a model for the treatment of mice with syngeneic lymphocytes sensitized against tumor cells in vitro. Mice were given subcutaneously tumor cells that spontaneously metastasized to the lungs. The tumors developing locally were surgically removed and the mice were inoculated with sensitized lymphocytes 1 day later. Prevention of death by lung metastases was the measure of immunotherapy. Only approximately equal to 30-40 percent of mice receiving control treatment survived, whereas approximately equal to 70 percent survived that received lymphocytes sensitized in vitro against the tumor cells. Hence sensitization of syngeneic lymphocytes against tumor cells in vitro and injection of the lymphocytes into the host after removal of a local tumor prevented the development of lethal metastases.

Induction of T-cells differentiation in vitro by thymus epithelial cells

Thymus-reticular epithelial cells (TE-cells) were grown in a cell culture devoid of any lymphocytic elements. These cells were able to induce T-cell differentiation in spleen cells from T-dificient mice as expressed by con-A responsiveness and GvH reactivity. It was also shown that xenogeneic rat TE cells were as effective in the induction of T-cell differentiation in vitro as syngeneic TE cells. This system is therefore ideal for the study of T-cell development.

Increased incidence of urethane induced lung adenomata by autosensitized lymphocytes

The present work investigates the influence of autosensitized lymphocytes on the carcinogenic response of the host. Urethane treated SWR mice received 6 fortnightly injections of lymphocytes sensitized in vitro against syngeneic fibroblasts. An increased incidence of lung adenomata was found in these mice compared with controls injected with unsensitized lymphoid cells or with lymphoid cells sensitized against unrelated transplantation antigens. Autosensitized lymphocytes also modified the response of host lymphoid cells to concanavalin A or to stimulation in a mixed lymphocyte culture assay. These results indicate that autoimmune lymphocytes may increase susceptibility of a host to the induction of tumours.