Graft-versus-host Response Research Articles

Abrogation of the Alloreactive Responses of Cadaveric Donor Intestinal Lymphocytes by Intraoperative Campath-1H Exposure

A number of recent reports in clinical and experimental intestinal transplantation have suggested that the donor lymphocytes present in and around the gastrointestinal system are potent mediators of graft-versus-host (GvH) reactivity and that GvH responses may contribute to posttransplant morbidity. Therefore, we have tested the proliferative and cytotoxic capabilities of gut-associated lymphocytes from cadaveric donors obtained prerevascularization (pre-r) and about 6 hours postrevascularization (post-r) in recipients pretreated with Campath-1H antibody (alemtuzumab). Mixed lymphocyte reactions (MLR) were performed with lymphoid cells isolated from intestinal epithelial mucosa, lamina propria, and lymph nodes. The pre-r lymphocytes responded strongly to both the recipient and third-party alloantigenic stimulating cells. However, similar preparations from the post-r samples responded in MLR at significantly lower levels ( P < .01). This post-r decrease in responsiveness was not observed in similar lymphocyte samples obtained from donors of recipients not treated with Campath-1H. Both the pre-r and post-r samples had similar flow cytometric profiles, suggesting that there was no receptor loss in these lymphoid tissues by the short-term 6-hour exposure to Campath-1H given to the recipient. Conversely, in preliminary experiments where the donor were treated with Campath-1H, it was observed that very few lymphocytes could be obtained from intestinal tissues ( n = 3). These results suggested that Campath-1H treatment of the recipient could bring about a drastic reduction in an otherwise strong GvH reactivity by the donor intestinal immune cells.

Temporal discordance between graft-versus-leukemia and graft-versus-host responses: A strategy for the separation of graft-versus-leukemia/graft-versus-host reactivity?

The graft-versus-leukemia (GVL) effect is often coexpressed with graft-versus-host disease (GVHD), although the temporal kinetics of these responses have not been critically examined. To evaluate this question in the absence of the confounding effects of the conditioning regimen, 23 patients who received donor lymphocyte infusions from HLA-identical siblings and subsequently developed GVHD and/or a GVL response were studied to determine whether these were temporally synchronous events. The GVL effect occurred significantly earlier than GVHD, being that 19 of 23 patients had a sustained GVL response that antedated the onset of clinical GVHD. The median difference between time to GVL and graft-versus-host (GVH) reactivity in the entire cohort was 14 days. There was no correlation between total T-cell dose and the relative onset of GVL versus GVH reactivity, indicating that temporal dissociation of GVL and GVH responses was not a function of the absolute number of infused donor T cells. These data support existing murine bone marrow transplantation studies indicating that GVL and GVH responses are not temporally synchronous events and raise the possibility that targeted elimination of alloreactive donor T cells after bone marrow transplantation may be an effective strategy for the separation of GVL/GVH reactivity.

Clinical Tolerance: the end of the beginning.

Clinical Tolerance: the end of the beginning.

Temporally discordant graft versus leukemia (GVL) and graft versus host (GVH) responses after donor lymphocyte infusion therapy for relapsed chronic myelogenous leukemia

Separation of GVL and GVH reactivity after allogeneic hematopoietic stem cell transplantation remains an elusive clinical goal. We have previously observed in murine models that GVL and GVH reactivity can be dissociated based on temporal kinetics whereby the GVL effect antedates GVHD allowing mice mice to eliminate leukemia before they develop lethal GVHD (J Immunol 170:2003). To determine if this observation was relevant to man, we examined the tempo of GVL and GVH reactivity in a cohort of patients receiving DLI for relapsed CML where the kinetics of these responses could be examined in the absence of the confounding effects of the conditioning regimen and immunosuppressive therapy. Between 1992–2002, 38 patients with relapsed CML after allogeneic BMT from either HLA-identical sibling or unrelated donors were treated with DLI. Patients were excluded if they did not have both an antileukemic response and GVHD after DLI (n = 16) or were administered prolonged (>2 weeks) IFN therapy after DLI to control blood counts (n = 4). The remaining 18 patients were in either accelerated phase 4/18 (22%), chronic phase 9/18 (50%), cytogenetic relapse 4/18 (22%), or molecular relapse 1/18 (5%) at time of DLI. All had sustained cytogenetic (CGR) and/or molecular responses (MR)(Houston criteria) attributable to DLI along with documented clinical GVHD. The median time to earliest cytogenetic or molecular response was 53 days (20 -97) while time to complete cytogenetic or molecular remission was 82 days (32 -230). The inital onset of GVHD occurred at a median of 59 days (32 -157) in the entire patient cohort. Eleven of 18 patients had evidence of a CGR or MR that occurred a median of 22 days (range 5–121)before onset of GVHD. In 4 patients a CGR or MR was documented concurrently with GVHD, indicating that a GVL response had already occurred before GVHD became clinically evident, while in 3 patients GVHD developed before an antileukemic response was observed. In 7 patients, the CGR or MR was already complete before GVHD began and antedated the onset of GVHD by a median of 14 days (range 0–84). These data indicate that GVH and GVL responses are not synchronous events but can occur with temporally discordant kinetics. These data also provide rationale for therapeutic strategies designed to dissociate these two events after allogeneic SCT by the targeted elimination of alloreactive donor T cells after the GVL effect has occurred but before clinical GVHD has developed.

T Lymphocytes Are Direct, Aryl Hydrocarbon Receptor (AhR)-Dependent Targets of 2,3,7,8-Tetrachlorodibenzo- p-dioxin (TCDD): AhR Expression in Both CD4 + and CD8 + T Cells Is Necessary for Full Suppression of a Cytotoxic T Lymphocyte Response by TCDD

The cellular basis for the potent suppression of T cell-mediated immune responses in mice following exposure to 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD) is not fully understood. Although activation of the aryl hydrocarbon receptor (AhR) is required, the specific AhR + cells that transduce the suppression have been difficult to identify in vivo. The recent availability of AhR −/− mutant mice has provided a resource for novel approaches to investigate the direct targets of TCDD. In our studies, we used an in vivo acute graft versus host (GVH) model of T cell immunity to address the direct AhR-dependent effects of TCDD on T cells. In this model, T cells from C57B1/6 mice are injected into C57B1/6 × DBA/2 F1 host mice. The injected T cells recognize the MHC disparity of the host cells, resulting in the generation of an antihost cytotoxic T lymphocyte (CTL) response. By comparing the ability of TCDD to suppress the CTL response of T cells obtained from AhR +/+ and AhR −/− C57B1/6 mice, the need for AhR expression in T cells themselves could be assessed. The results of these studies showed that the CTL response of T cells from AhR +/+ mice was highly suppressed when the F1 host mice were treated with 15μg/kg TCDD. TCDD treatment also protected the F1 host mice from the loss of body weight that accompanies the induction of the GVH response. In contrast, when grafted T cells were derived from AhR −/− mice, there was no suppression of the CTL response by TCDD, and the host animals lost significant body weight. Furthermore, when T cells from AhR +/+ and AhR −/− mice were separated into CD4 + and CD8 + subsets and recombined using one subset from each donor prior to injection into the F1 host, suppression of the CTL response by TCDD was still apparent, but the degree of suppression was significantly reduced when either subset was AhR −/−. These results indicate that direct AhR-dependent effects of TCDD occur in both CD4 + and CD8 + T cell subsets and both T cell subsets contribute to the full suppression of the CTL response by TCDD.

Minor H antigens: genes and peptides.

In this review, we describe the evidence from which the existence of non-MHC histocompatibility (H) antigens was deduced, the clinical setting of bone marrow transplantation in which they are important targets for T-cell responses, and the current understanding of their molecular identity. We list the peptide epitopes of the human and murine minor H antigens now identified at the molecular level, their MHC restriction molecules and the genes encoding them. Identification of the peptide epitopes allows T-cell responses to these antigens following transplantation of MHC-matched, minor H-mismatched tissues to be enumerated using tetramers and elispot assays. This will facilitate analysis of correlations with host-versus-graft (HVG), graft-versus-host (GVH) and graft-versus-leukaemia (GVL) reactions in vivo. The potential to use minor H peptides to modulate in vivo responses to minor H antigens is discussed. Factors controlling immunodominance of T-cell responses to one or a few of many potential minor H antigens remain to be elucidated but are important for making predictions of in vivo HVG, GVH and GVL responses and tailoring therapy after HLA-matched bone marrow transplantation and donor lymphocyte infusion.

Use of allochimeric proteins to mitigate graft-versus-host and host-versus-graft immune responses to rat small bowel allografts.

We aimed to identify the polymorphic epitopes that mitigate graft-versus-host disease (GvHD) and host-versus-graft response (HvGR) toward rat small bowel allografts in rats. We tailored class I major histocompatibility complex (MHC) allochimeric antigens encoding 10 al-helical (alpha(1h)l58-80-RT1.Aa) or 4 (alpha(1h)l/u62-69-RT1.Aa) polymorphic amino acids. In the GvHD model, ACI (RT1a) donors were pretreated (day -14) with an intrathymic injection of alpha(1h)l58-80-RT1.Aa, alpha(1h)l/u62-69-RT1.Aa, or RT1.Al protein, with or without simultaneous intravenous injection of anti-T-cell receptor R73 monoclonal antibodies. Wistar-Furth (WF; RT1u) donors were tested with a similar protocol. In the HvGR model, ACI recipients were treated with a protocol designed to induce transplantation tolerance toward WF heart allografts: a portal vein injection of alpha(1h)l/u62-69-RT1.Aa protein and cyclosporine (4 mg/kg, intramuscular; days 0-6). GvHD was prevented in all (ACI x LEW) F1 recipients (RT1a/l) by pretreating ACI donors with R73 monoclonal antibody and recipient RT1.Al or alpha(1h)l58-80-RT1.Aa protein. Similarly, pretreatment of WF donors with RT1.Aa protein also prevented GvHD in (ACI x WF) F1 recipients. However, in a combined GvHD/HvGR model, ACI recipient perioperative treatment designed to prevent HvGR only modestly prolonged WF small bowel allograft survival (27.7+/-5.3 days compared to 17.4+/-4.6 days in the cyclosporine-alone group). In contrast, application of the two protocols significantly prolonged WF allograft survival (55.6+/-34.6 days), with two of seven recipients surviving more than 100 days. Simultaneous inhibition of GvHD and HvGR significantly prolongs small bowel allograft survival.

T Cells Specific for a Polymorphic Segment of CD45 Induce Graft-Versus-Host Disease with Predominant Pulmonary Vasculitis

To study the character of graft-vs-host disease (GVHD) induced by T cells specific for hemopoietic cells, T cells specific for a polymorphic segment of CD45 were transferred into CD45 congenic mice. C57BL/6 mice that express the CD45b allele were immunized with a 13 mer peptide representing the polymorphic segment (p257-268) of CD45a protein. Conversely, C57BL/6 mice congenic for CD45a were immunized with the CD45b peptide. CD4+ T cells specific for allelic CD45 peptides were elicited. Importantly, T cells specific for CD45 peptides proliferated specifically and vigorously in response to spleen cells expressing the appropriate polymorphic CD45 protein. T cells specific for CD45 induced a substantial graft-vs-host response (GVHR) with predominant early pulmonary vasculitis and later more widespread interstitial mononuclear cell infiltration and alveolitis. No GVHR was induced in bone marrow chimeras expressing only donor hemopoietic cells. Thus, donor T cell recognition of host hemopoietic cells is sufficient to elicit GVHR, but the classical skin, liver, and gut manifestations of GVHD were not observed. The CD45-specific T cells used secreted Th1 cytokines, but without detectable soluble IL-2. Studies using CD45-specific T cells with different effector functions might allow further dissection of donor cell requirements for GVHD syndromes.

The popliteal lymph node assay in 1996

The popliteal lymph node (PLN) assay is based on the assumption that a mechanism similar to a graft-versus-host (GvH) reaction is involved in ‘GvH-like’ drug-induced side-effects, including generalized lymphadenopathy, serum sickness-like disease, scleroderma-like reaction and the lupus syndrome. An increased PLN weight 7–10 days after injection of the test article into the footpad is generally held as a positive response. Most, if not all compounds reported to induce pseudo-GvH side-effects in man (namely positive model compounds) have been shown to induce positive PLN responses in mice and/or rats. Reproducible results have been obtained in several laboratories, in some instances blindly. However, positive responses have also been obtained with the negative model compounds acetone and imipramine. Flow cytometry analysis and conventional histology failed to help differentiate between a true GvH response and a primary irritative effect. In order to confirm the potential value of the PLN assay to predict the risk for drug-induced GvH-like reactions, mechanistic studies are urgently needed.

Immunosuppressive Effects of the Cyclosporin Derivative SDZ IMM 125 on Kidney Allograft in the Dog and Small Bowel and Pancreas Allografts in the Rat

The efficacy of SDZ IMM 125 in preventing allograft rejection was evaluated in kidney transplantation in the dog and orthotopic small bowel and heterotopic pancreas transplantation in the rat. Seven groups (n= 6) were involved in dog kidney transplantation. Untreated recipients rejected kidney allografts with a mean survival time (MST) of 8.0 ± 1.8 days. There was a graded dose response in SDZ IMM 125-treated groups: 10 mg/kg/day, MST 11.3 ± 3.5 days,P= 0.065; 15 mg/kg/day, MST 44.8 ± 10.8 days,P= 0.0001; and 20 mg/kg/day, MST 47.3 ± 5.6 days,P= 0.0001, same as in cyclosporin A (CsA)-treated groups: 10 mg/kg/day, MST 25.8 ± 13.7 days,P= 0.001; 15 mg/kg/day, MST 38.3 ± 18.1 days,P= 0.002; and 20 mg/kg/day, MST 38.7 ± 17.7 days,P= 0.002. Low dose of SDZ IMM 125 (10 mg/kg/day) was less effective in prolonging the graft survival than low dose of CsA. High dose (20 mg/kg/day) treatment of both SDZ IMM 125 and CsA led to abnormal recipient liver enzymes alanine aminotransferase and aspartate aminotransferase postoperatively. A histopathological study demonstrated fatty degeneration of hepatic cells in both 20 mg/kg/day SDZ IMM 125- and CsA-treated groups. We also tested the effect of SDZ IMM 125 in orthotopic small bowel transplantation with three combinations, namely host-versus-graft (HVG), graft-versus-host (GVH), and combined HVG and GVH immune responses and pancreas transplantation in the rat with different doses. The results indicate that SDZ IMM 125 is a potent immunosuppressant to prolong the kidney allograft survival in the dog, to alleviate HVG and GVH responses in small bowel transplantation, and to delay pancreas allograft rejection in the rat. Low dose of SDZ IMM 125 is less effective than a similar dose of CsA to prevent kidney allograft rejection in the dog.

Graft Versus Host Response: Clinical and Biological Relevance After Transplantation of Solid Organs

Graft Versus Host Response: Clinical and Biological Relevance After Transplantation of Solid Organs

Tepoxalin, a novel immunomodulatory compound, synergizes with CsA in suppression of graft-versus-host reaction and allogeneic skin graft rejection.

Tepoxalin, a dual 5-lipoxygenase and cyclooxygenase inhibitor with nonsteroidal antiinflammatory effects, has recently been shown to suppress NF kappa B transactivation and inhibit T cell proliferation via a mechanism very different from cyclosporine (CsA). In this report, we demonstrate that this novel immunosuppressive effect of tepoxalin is manifested in in vivo transplantation models. Tepoxalin suppressed murine spleen cell proliferation in a mixed lymphocyte reaction (MLR) with an IC50 of 1.3 microM. Coadministration of tepoxalin and CsA in MLR cultures showed an additive inhibitory effect. Oral administration of tepoxalin at 12 mg/kg/day to mice suppressed local graft-versus-host (GVH) responses by about 40% (n = 10). Combination of tepoxalin and CsA at suboptimal doses synergized their immunosuppressive effects on GVH responses (n = 20). In skin transplantation, the median survival time of allogeneic BALB/cByJ (H-2d) mouse skin grafted onto C3H/HeJ (H-2 kappa) mice was 10.5 days (n = 8), and was prolonged to 15.0 days (n = 9) for recipient mice administered tepoxalin at 50 mg/kg/day. Coadministration of suboptimal doses of tepoxalin (12.5 mg/kg/day) and CsA (50 mg/kg/day) prolonged skin graft rejections dramatically (55% of the grafts survived for more than 40 days, n = 9). Taken together, these results demonstrate that tepoxalin is a potent immunomodulatory compound that, when combined with CsA, provides synergistic immunosuppressive activity. The fact that tepoxalin and CsA act on different transcription factors, NF kappa B and NFAT respectively, might explain the synergistic suppressive effects when both compounds were used. Tepoxalin could be an important addition to the cohort of immunosuppressive therapies currently used in solid organ and bone marrow transplantations.

RAPAMYCIN GRAFT PRETREATMENT IN SMALL BOWEL AND KIDNEY TRANSPLANTATION IN THE RAT

The effect of rapamycin (RAPA) as graft pretreatment was evaluated in orthotopic small bowel and kidney allotransplantation (Tx) in the rat. In the small bowel Tx model, six groups were involved, each including three combinations for evaluation of host-versus-graft (HVG) [Lewis (LEW) x Brown Norway (BN) (LBN)-F1-->Lewis], graft-versus-host (GVH) (LEW-->F1), and combined HVG and GVH immune responses (BN-->LEW). RAPA graft pretreatment alone (16 micrograms/ml x 3 ml) was able to induce a modest but significant prolongation of survival in all three combination models compared with controls (P < 0.05). The same was observed for low dose CsA treatment (2 mg/kg/day x 14 days) of the recipient only (P < 0.05). Combination of graft pretreatment with RAPA and CsA recipient treatment produced a marked prolongation of survival especially in HVG response. Recipients treatment with one 48-microgram bolus of RAPA i.v. immediately after graft revascularization failed to achieve any prolongation of survival for the GVH or combined HVG and GVH responses. This seems to exclude a "carry-over" effect of RAPA from graft to recipient. RAPA efficacy was also clearly confirmed in the kidney graft pretreatment model as compared to recipient treatment with an equivalent RAPA dose. These results demonstrate that graft RAPA pretreatment prolongs SB survival after Tx in the rat for HVG, GVH, and bidirectional immune responses. Intragraft interaction with passenger leukocytes or APC function appears as one of the possible mechanisms. RAPA graft pretreatment potentiates low dose CsA recipient treatment suggesting a possible use in clinical organ Tx.

Impaired Response to Alloantigens in Murine Biliary Obstruction

Male Lewis strain rats underwent bile duct ligation and division (BDL), selective hepatic duct ligation (SHL), simple ligation and recanalization (RCN), or sham celiotomy (SC). Unoperated rats served as normal controls (NC). At intervals of 1, 2, and 3 weeks postoperatively, the popliteal lymph node assay was used to study host versus graft (HVG) response. LBN-F 1 splenocytes (5 × 10 6) were injected into the hind foot pads, and the contralateral foot pad was injected with medium as a control. The popliteal lymph nodes were removed and weighed 7 days later. In the BDL group, HVG response was significantly impaired at 1 (BDL, 12,9 ± 5.1 mg; SC, 21.6 ± 2.6; NC, 22.4 ± 9.4; P < 0.005, BDL vs SC or NC), 2 (BDL, 12.6 ± 5.6; SC, 19.1 ± 3.0; NC, 15.8 ± 5.8; P < 0.001, BDL vs SC), and 3 weeks (BDL, 8.9 ± 3,9; SC, 21.7 ± 6.3; NC, 16.7 ± 3.8; P < 0.001, BDL vs SC or NC). SHL did not cause hyperbilirubinemia or impair the HVG response at 2 weeks (SHL, 17.2 ± 4.5; NC, 16.7 ± 7.4). The serum bilirubin was normal 2 and 3 weeks after RCN, and the HVG response was normal in both groups; however, the HVG response was somewhat lower at 2 weeks (RCN, 12.1 ± 2.1) than at 3 weeks (RCN, 18.2 ± 4.4; P ± 0,01, RCN 2 weeks vs RCN 3 weeks). BDL causes significant impairment in the murine response to alloantigens as measured by the popliteal lymph node assay. Preservation of sufficient normally drained hepatic parenchyma to prevent hyperbilirubinemia also preserves the HVG response, as does incomplete obstruction (RCN).

The popliteal lymph node assay: a tool for studying the mechanisms of drug-induced autoimmune disorders

Whereas it is still impossible to predict the risk for organ-specific drug-induced autoimmune disorders in animals, a large body of evidence suggests that the popliteal lymph node assay (PLNA) in mice or rats is instrumental to predict systemic drug-induced autoimmune disorders. Metabolites may be involved instead of the parent molecules in a few instances as shown by studies using animals pretreated with enzyme inducers. Histological examination can help distinguish primary irritants, contact sensitizers and ‘autoimmunogenic’ compounds. That a Graft-vs-Host (GvH)-like mechanism may be involved was further substantiated by the finding that histological features of a positive PLNA response to e.g. streptozotocin, were quite similar to those of a ‘true’ local GvH response. In addition, this model is expected to be useful to improve our understanding of the mechanism (s) involved in systemic autoimmune reactions by studying the profile of PLN lymphocyte subpopulations and of released cytokines.

Alloreactive lymphocytes from T cell receptor (beta-chain) transgenic mice do not mediate a graft-versus-host reaction.

The injection of mature T cells into a tolerant or immunocompromised allogeneic host animal produces a graft versus host response (GVHR) that can result in splenomegaly, immunosuppression and death of the host animal. We demonstrate here that lymphocytes from T cell receptor beta-chain (TCR-beta) transgenic mice, in which the expression of the transgene inhibits endogenous beta- and gamma-gene rearrangements and thus causes abnormal T cell development, are unable to mediate a GVHR. The GVHR was measured after the injection of lymphocytes from transgenic mice into normal F1 mice and also after transplantation of bone marrow and lymphocytes from transgenic mice into lethally irradiated F1 recipients. In both systems, cells from transgenic mice failed to produce a significant GVHR. Cells from the transgenic mice were able to recognize the foreign histocompatibility Ag of the host in vitro and in vivo although the transgenic mice rejected skin grafts more slowly than controls. Thus, lymphocytes from transgenic mice were unable to produce a GVHR despite the presence of alloreactive T cells. These results suggest that lymphocytes from TCR-beta transgenic mice fail to mediate a GVHR either because lymphocytes with a single transgenic TCR-beta chain have a limited ability to recognize allogeneic cells in vivo or because the transgenic mice lack lymphocyte subsets that are important for the mediation of a GVHR.

Dissociation of immunosuppression by chlorpromazine and trifluoperazine from pharmacologic activities as dopamine antagonists

Neuroleptic compounds may affect the immune system through a variety of mechanisms. Most possess a complex pharmacology, which makes specific, causal relationships difficult to discern. In this study, a series of experiments was performed to examine the effects of dopamine antagonists on a battery of immunologic parameters. Mitogen-induced lymphocyte proliferation in vitro was inhibited by haloperidol, chlorpromazine, and trifluoperazine at 10, 1 and 1 gmM concentrations, respectively. Sulpride and metoclopramide had no direct effect in vitro. In vivo lymphocyte proliferation was significantly reduced by chlorpromazine at the highest tested doses (12.5 and 15 mg/kg) and by trifluoperazine at the highest tested dose (30 mg/kg). All other dopamine antagonists had no significant effect on in vivo lymphocyte proliferation. A murine graft vs host (GVH) response was unaffected by haloperidol, sulpiride, and metoclopramide. Chlorpromazine and trifluoperazine exhibited significant inhibition of the GVH response at the highest doses only (15 and 30 mg/kg, respectively). In a picryl chloride induced delayed type hypersensitivity (DTH) assay, haloperidol, metoclopramide, and sulpiride had no effect. However, both chlorpromazine and trifluoperazine significantly reduced DTH-induced paw swelling at the higher doses (7.5 mg/kg, and 10 and 30 μm/kg, respectively). These studies indicate that the more specific dopamine antagonists (e.g. sulpiride, metoclopramide, and haloperidol) do not share the immunologic profiles of chlorpromazine and trifluoperazine, suggesting that these effects of chlorpromazine and trifluoperazine are not related to their dopamine antagonist properties.

Kinetics and morphology of chemically induced popliteal lymph node reactions compared with antigen-, mitogen-, and graft-versus-host-reaction-induced responses

Changes in the popliteal lymph node (PLN) in mice evoked by a local graft-versus-host (GVH) reaction and by a single injection of various agents into the hind footpad were compared. The drug diphenylhydantoin induced similar weight changes in time as the GVH reaction. More vigorous and protracted reactions were induced by the drug nitrofurantoin and the contact sensitizer dinitrochlorobenzene, whereas the antigens lipopolysaccharide and sheep erythrocytes caused very moderate and short-lasting weight changes. Alterations of lymph node architecture upon injection of diphenylhydantoin resembled those observed during the GVH response. Some quantitative and qualitative differences were noted for nitrofurantoin, but clearly deviant morphological alterations were seen in response to lipopolysaccharide and sheep erythrocytes. The PLN reaction to dinitrochlorobenzene had features of both the GVH reaction and the antigen-induced responses. These findings support the concept that some drugs and chemicals may induce or exacerbate lymphoproliferative disorders by GVH-like mechanisms.

Relationship between circulating thyroid hormones and cell-mediated immunity in immature male chickens

The objective of this experiment was to examine the relationship between circulating triiodothyronine (T3), thryoxine (T4) and cell-mediated immunity in immature male chickens. Three week old Single Comb White Leghorn male chicks were used as the experimental animals. In order to produce a wide range of circulating thyroid hormone concentrations, birds were divided into groups and received one of nine treatments including surgical thyroidectomy; 0.1% propylthiouracil (PTU) in the feed; 1 ppm T3 and 10 ppm T4 in the feed. The graft versus host (GvH) response and response to phytohemagglutinin (PHA) were measured at 6 weeks of age. Total and differential white blood cells were counted. Birds were bled, weighed, sacrificed, and the lymphoid organs were removed and weighed. Concentrations of T3 and T4 were measured in the birds from all treatment groups. There were positive correlations between thyroid hormones, mainly T3, and weights of thymus and spleen. T4 but not T3 was positively correlated with number of circulating lymphocytes. There were no significant correlations between circulating T3 and T4 and either PHA or GvH responses. It was concluded that physiological levels of thyroid hormones are needed to maintain normal weights of thymus and spleen and a normal level of circulating lymphocytes. Furthermore, we conclude

Graft-versus-host response in sex-linked dwarf, autosomal dwarf and control K strain chickens

Two independent experiments were conducted to examine the ability of 1) the autosomal-dwarf (ADW) strain and 2) the sex-linked (SLD)strain chicken to make a Graft-versus-Host (GvH) response. In each experiment the GvH response of the dwarf strain was compared to the GvH response of a normal growing control strain, the Cornell K strain chicken. All 3 strains were homozygous B15/B15 at the major histocompatibility complex. GvH responsiveness of peripheral blood lymphocytes (PBL) from females of each strain was assessed at various intervals from 1.5 to 20 months of age using the chorio-allantoic membrane (CAM) assay.The GvH response in female chickens from the ADW strain was significantly higher than in K strain females after the birds had reached sexual maturity (after 5.5 months). The GvH response in females from the SLD strain was, however, significantly lower than in the K strain females throughout the experiment. All strains tended to have a biphasic GvH response. There was a significant increase in GvH responsiveness from 1.5 to 5.5 months of age in chicks from all strains. In the SLD and K strain chickens, this was followed by a drop in the GvH response until 8.5 months of age. In 16-to 20-month-old SLD and K strain hens, the ability to mount a GvH response returned to levels observed in younger (5.5 months) pullets. The GvH responsiveness of the ADW strain remained at a constant level from 5.5 to 12 months of age. However, a second peak in GvH responsiveness was observed in 16-month-old ADW strain hens.Strain differences in GvH responsiveness may be due to the known hormonal abnormalities in the dwarf strains. The suitability of these dwarf strains for the study of endocrine-immune interrelationships is discussed.