Outcomes of kidney transplantation from elderly deceased donors of a Korean registry

To overcome organ shortage, expanded criteria donors, including elderly deceased donors (DDs), should be considered. We analyzed outcomes of kidney transplantation (KT) from elderly DDs in a nationwide study. In total, data of 1049 KTs from DDs using the database of Korean Organ Transplantation Registry (KOTRY) were retrospectively analyzed based on the age of DDs: age ≥60 years vs. <60 years. Clinical information, graft status, and adverse events were reviewed in DDs and recipients. The mean age of the 1006 DDs was 51.04±10.54 years, and 21.5% of donors were aged ≥60 years. Elderly DDs had a significantly higher prevalence of diabetes and hypertension and higher Kidney Donor Risk Index (KDRI) and Kidney Donor Profile Index (KDPI). The mean age of the recipients was 47.45±14.87 years. Patients who received KT from elderly DDs were significantly older (53.12±15.14 vs. 45.88±14.41, P<0.001) and had a higher rate of diabetes (41.9 vs. 24.4%, P<0.001). Graft outcomes were not significantly different. Renal function was similar between the groups at the time of discharge and at 6 months, 1 year, and 2 years after KT. The rate of delayed graft function (DGF) was not significantly different. Risk factors of DGF were significantly different in DDs aged ≥60 years and <60 years. In the multivariable model, male sex (odds ratio: 3.99, 95% confidence interval: 1.42–11.22; P = 0.009) and KDRI (12.17, 2.23–66.34; P = 0.004) were significant risk factors for DGF in DDs aged ≥60 years. In DDs aged <60 years, thymoglobulin induction (2.62, 1.53–4.48; P<0.001) and continuous renal replacement therapy (3.47, 1.52–7.96; P = 0.003) were significant factors. Our data indicated that graft outcomes, including renal function and DGF, were similar for elderly DDs and DDs aged <60 years. Elderly DDs might be considered tolerable donors for KT, with active preoperative surveillance.

Lymphocyte subset reconstitution in pediatric liver recipients induced with steroid-free rabbit anti-human thymocyte globulin

Multiple measurements of lymphocyte subsets in 91 children treated with steroid-free tacrolimus, and rabbit anti-human thymocyte globulin induction demonstrate early reconstitution of T-cytotoxic cells, and gradual reconstitution of all other subsets, which is complete after one yr. Rejection-prone children demonstrate significantly higher counts of lymphocytes and all subsets prior to liver transplantation, and may exemplify one basis for enhanced baseline immunocompetence.

[Pharmacokinetics of antithymocyte globulin in recipients under-going HLA partially matched hematopoietic stem cell transplantation]

The aim of study was to investigate the pharmacokinetics and distribution of antithymocyte globulin (ATG) in recipients of partially HLA-matched hematopoietic stem cell transplantation. Fifteen patients with hematological disorders were received hematopoietic stem cell transplantation from partially HLA-matched related donor between October 2003 and October 2004 in the Institute of Hematology and People Hospital, Peking University. All patients including 5 cases of AML, 6 cases of CML, 3 cases of ALL, 1 case of AA were consecutively enrolled in the present study after providing written informed consent. Antithymocyte globulin was administered before allogeneic hematopoietic stem cell transplantation at a dose of 2.5 mg/kg daily for 4 consecutive days (total dose of 10 mg/kg) in the conditioning regimen. The concentration of rabbit ATG in the serum of 15 patients was measured using a new enzyme-linked immunoabsorbent assay (ELISA) for the Fc portion of rabbit IgG. The results showed that the washout phase of ATG elimination was analyzed over 0 - 120 days, results were well-fitted by a single exponential decay giving a mean elimination half-life (t(1/2) beta) of 29.67 +/- 2.60 days. A mean value for the apparent volume of distribution of ATG (V) obtained by analysis of data was 0.12 +/- 0.02 L/kg body weight. The serum concentration of ATG increased up to 44.8% at 5 day before transplantation, peak concentration of ATG was 136.0 +/- 10.3 mg/L, its concentration slowly descend at 0 day, fall up to 7.1 +/- 0.06 microg/ml at 90 day after dosing; t(max) 4.8 +/- 0.7 days; According to AIC (Akaike's information criterion), two compartment model of ATG was estimated. It is concluded that the conditioning regimen containing the dosage of 10 mg/kg of ATG is effective and safely in recipients of partially HLA-matched hematopoietic stem cell transplantation. There is no racial difference in the pharmacokinetics of ATG.

Interleukin-1 and host control of pulmonary histoplasmosis

We found that interleukin (IL)-1beta levels were elevated in the lungs of mice infected with Histoplasma capsulatum. Hence, we examined the influence that IL-1beta and IL-1 signaling has on host defenses against pulmonary histoplasmosis. In IL-1 receptor 1 knockout (IL-1R(-/-)) mice challenged intratracheally, fungal recovery on day 7 after infection exceeded that in wild-type (WT) mice. Antibody neutralization of IL-1beta also exacerbated infection. For both groups of mice, the absence of bioactive cytokine led to a failure to control infection in a high proportion of mice. The absence of signaling had a modest effect on host resistance in mice with secondary histoplasmosis. Several perturbations in host defense mechanisms were detected in the lungs of IL-1R(-/-) mice. The number of CD4+ cells was decreased, and transcription of the gene for inducible nitric oxide synthase was depressed transiently. IL-4 and IL-10 levels were elevated in the lungs of IL-1R(-/-) mice, compared with those in the lungs of WT mice. Conversely, interferon- gamma levels were decreased. Thus, IL-1 contributes to host resistance to infection with H. capsulatum.

A Conjugate of a Tumor-Targeting Ligand and a T Cell Costimulatory Antibody To Treat Brain Tumors

T cell immunotherapy is a potential strategy for the treatment of brain tumors because it offers a high degree of specificity, the ability to extravasate into solid tumors, and the potential for eliciting a long-term protective immune response. Various approaches have been developed to overcome T cell immune tolerance to cancer, including the use of cytokines and bispecific antibodies. T cell stimulation with the proinflammatory cytokine IL-12 can elicit antitumor immunity. T cell activation can be increased using bispecific antibodies against activating molecules on the surface of T cells and a tumor antigen. We studied the effects of systemic IL-12 administration in combination with a conjugate of an anti-CD28 antibody and a ligand for the folate receptor. The high affinity folate receptor is expressed on endogenously arising choroid plexus tumors of SV11 mice, which are transgenic for large T antigen under the control of the SV40 promoter. SV11 mice are immunocompetent, yet immunologically tolerant to large T antigen expressed by choroid plexus tumors. MRI analysis showed that the administration of IL-12 and anti-CD28 Fab/folate significantly slowed tumor growth. Proliferating CD8(+) T cells were found in choroid plexus tumors of treated animals. Treatment of animals with IL-12 + anti-CD28 Fab/folate prolonged survival compared to IL-12 alone. Cytokine treatment combined with tumor-targeted costimulation may be a useful adjunct treatment.

Direct binding of antithymoctye globulin to haemopoietic progenitor cells in aplastic anaemia

Antithymocyte globulin (ATG) is widely used in the treatment of aplastic anaemia (AA) and a response occurs in 60-80% of patients. However, its exact mechanism of action in the treatment of AA has yet to be determined. Previously, we have shown that ATG increases colony growth from purified bone marrow CD34+ cells of AA patients in vitro, and decreases stem cell apoptosis and the expression of soluble Fas receptor after ATG therapy in vivo. The aim of this study was to further examine the association of ATG with AA haemopoietic progenitor cells. We describe here that ATG bound directly to CD34+ cells. Forty-six patients and 20 normal control subjects were studied. ATG bound to CD34+ cells in normal control subjects (mean 90.38%) as determined by flow cytometry. The mean percentage of CD34+ cells binding to ATG was 59.90% in untreated aplastic patients, 83.24% in partial responders, 58.3% in non-responders and 62.73% in relapsed patients. In completely recovered patients, ATG binding was indistinguishable from control subjects. The functionality of AA patients' haemopoietic progenitor cells was assessed using colony assays. These results demonstrate the direct binding of ATG to CD34+ cells and suggest that differences in its binding to AA CD34+ cells could reflect functional differences in the haemopoietic stem cell compartment throughout the disease process.

Increased in vivo mitogenicity of anti-TCR/CD3 monoclonal antibody through reduced interaction with Fcgamma receptors

Since its initial clinical use in 1980, anti-TCR/CD3 monoclonal antibody (mAb) has been shown to be a potent immunosuppressive agent in the prevention of renal allograft rejections. However, toxic side effects caused by release of cytokines, predominantly from activated CD4+ T-cells, remain a major problem with the use of these reagents. Previous work has shown that this activation is mediated via antibody binding to Fcgamma receptors (FcgammaR) on host effector cells. In the present study, we have demonstrated in an in vivo mouse model that the anti-TCR/CD3 mouse mAb 7D6, as well as that from rat (17A2) and hamster (H57-597), induce a gradual depletion of host CD4+ T-cells without any apparent proliferative effects on the cells. In contrast, when treatment with these mAbs was combined with a mAb (2.4G2) that blocks the low-affinity Fcgamma receptors (FcgammaRII/III), we found that the in vivo actions of the anti-TCR/CD3 mAbs resulted in a significant expansion, rather than depletion, of CD4+ cells. The ability of 2.4G2 to reduce mAb 7D6-FcgammaR interaction was directly demonstrated in an in vitro assay system in which 2.4G2 partially suppressed 7D6-mediated T-cell responses. Taken together, our results have shown that some so-called "nonmitogenic" anti-TCR/CD3 mAbs in fact possess potent activating properties and that their mitogenic potential can be exposed by reducing their interaction with FcgammaR on host effector cells.

Granulocyte colony-stimulating factor-supported combined immunosuppressive therapy (antilymphocyte globulin, cyclosporine, and methylprednisolone) in patients with aplastic anemia: tolerability, efficacy, and changes in the progenitor cell compartment

Neutropenic infections are the major cause of morbidity and mortality in the treatment of aplastic anemia (AA) with antilymphocyte globulin (ALG), cyclosporin A (CSA), and methylprednisolone (MP). Recent data suggest a beneficial effect of administering G-CSF as an adjunct to immunosuppression. We have treated 11 consecutive patients with AA using a combined immunosuppressive regimen including ALG, CSA, and MP plus G-CSF at a dose of 5 microg/kg/day until neutropoietic recovery. In addition to measuring routine hematological parameters we have performed serial determinations of reticulocyte counts and in vitro progenitor cell cultures before and after therapy in order to assess their predictive value for treatment response and to determine the impact of therapy on early hematopoiesis. One patient died on day 34 of neutropenic septicemia. At 1 year, 81% of patients showed response to treatment. The median time to ANC values >0.5 and >1.0 x 10(9)/l were 19 and 35 days, respectively. Reticulocyte counts started to recover after 6 weeks, and transfusion independence was observed on day 52 for red blood cell transfusions and on day 53 for platelet concentrates. All patients with detectable colony formation in peripheral blood achieved a complete hematological remission, as compared with only one of five patients without progenitor cell growth. Although normal ranges were rarely achieved, there was a small but definitive improvement in progenitor cell numbers as compared with baseline values in most patients. Our results confirm the good tolerability and high efficacy of this G-CSF-supported combined immunosuppressive therapy for AA. Detectable colony growth at diagnosis seems to predict a high chance for complete hematological response.

The US multicenter double-blind, randomized, phase III trial of thymoglobulin versus atgam in the treatment of acute graft rejection episodes following renal transplantation: rationale for study design

In this study intended to establish equivalence between two antibody therapies for acute rejection in kidney transplant recipients, it was important to develop a rigorous protocol. Assurance of the presence of acute rejection was imperative. Therefore, due to the lack of literature support for clinical assessment of renal dysfunction, histologic diagnosis of acute rejection was required for enrollment in the study. Likewise, supportive literature for a correlation between response to anti-rejection therapy and the severity of rejection lead to the decision that the study should be stratified by a measurement of rejection severity for which Banff criteria were used. Finally, quantification of the response to therapy was also measured against the available literature and a large, newly developed international database of kidney transplant rejection episodes (the Efficacy Endpoints database) where serum creatinine, expressed as a percentage of the baseline level at the time of rejection was shown to be the most effective, available clinical marker of rejection response. Therefore, the US Multicenter Phase III Trial for comparing Thymoglobulin to Atgam in the treatment of acute rejection exhibits a unique and detailed study design that could be implemented in future trials as well as in clinical practice to improve assessment of outcomes.

Pharmacokinetics, foreign protein immune response, cytokine release, and lymphocyte subsets in patients receiving thymoglobuline and immunosuppression

The pharmacokinetics and immune response to the rabbit IgG of rabbit antihuman thymocyte globulin, Thymoglobuline has been characterized. A cytokine release pattern of TNF alpha and IL-6 but not IL-1 beta and IFN chi has been demonstrated with the first and not subsequent doses. An effect on lymphocyte depletion of peripheral blood with major subset suppression has been shown to last more than the 3-month observation period in patients on a regimen of quadruple sequential immunosuppression.

Anti-lymphocyte autoantibodies in systemic lupus erythematosus

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The pharmacokinetics of anti-thymocyte globulin (ATG) following intravenous infusion in man

The pharmacokinetics of the distribution and elimination of polyclonal rabbit antithymocyte globulin (ATG) following intravenous infusion was studied in patients who had received renal allografts. ATG concentration was measured using a new enzyme-linked immunoabsorbent assay (ELISA) for the Fc portion of rabbit IgG. Eleven patients received 14 courses of ATG supplied either by Fresenius (F-ATG) or Merieux (M-ATG) as a daily infusion of 2-6 mg/kg body weight for a therapeutic course lasting 5-10 days. The washout phase of ATG elimination was analysed over 0-300 days; results were well-fitted by a single exponential decay (r2 > 0.95) giving a mean elimination half-life (t0.5e) of 29.8 days (range 14.3-45.0, n = 9). Data for the first 4 days of treatment were analysed with linear regression to obtain a mean value for the apparent volume of distribution of ATG (Vd) of 0.12 l/kg body weight (range 0.07 to 0.17, n = 5). These results demonstrate that rabbit ATG has a long half-life in human plasma and an apparent volume of distribution of about twice plasma volume. The relationship between the concentration of ATG measured by this Fc receptor assay and its biological activity requires further study.

The effect of panel reactive antibodies and the donor specific crossmatch on graft survival after heart and heart-lung transplantation

Data from 699 cardiac and 290 heart-lung transplants has been analysed to determine the importance of the lymphocytotoxic crossmatch result and panel reactive antibody (PRA) status on graft survival. Donor reactive crossmatching was performed for 636 cardiac transplants. One year actuarial survival for a negative crossmatch (n = 580) was 73% compared to 56% for the positive crossmatch recipients (n = 56) p = 0.0014. Where crossmatches were performed on separated T and B cells, the T cell directed crossmatch was found to be highly predictive of graft failure in 289 cardiac transplants. One year survival for a negative crossmatch was 73% (n = 258), for B cell positive crossmatch recipients 62% (n = 24), and for a positive T cell crossmatch 28% (n = 7) (p = 0.001). Patients' PRA status were grouped into those with negative, medium and high frequencies. There was a trend (not statistically significant) for patients with PRA above 50% to have poor graft survival. Patients with PRA above 50% were significantly more likely to have a positive lymphocytotoxic crossmatch against donor lymphocytes. Donor reactive crossmatching was performed for 283 heart-lung transplants. One year actuarial survival for a negative crossmatch was 61% (n = 251) and for a positive result was 50% (n = 32), p = 0.02.(ABSTRACT TRUNCATED AT 250 WORDS)

The pharmacokinetics and pharmacodynamics of immunosuppressive agents

Designing immunosuppressive regimens for the pediatric transplant patient is challenging because one must balance the need to provide adequate immunosuppression without interfering with normal growth processes or causing long-term adverse consequences. To optimize immunosuppressive therapy and minimize toxicity, it is necessary for the nurse to be knowledgeable of the pharmacokinetic and pharmacodynamic characteristics of the various agents. It is also important to understand which drugs interact with immunosuppressive agents and how to manage these interactions.

[Etiology of idiopathic portal hypertension (IPH)--the role of immunological mechanism in IPH]

The pathogenesis of IPH is not yet clear, but immunological mechanism is suspected to play an etiologic role in IPH. In this study, we investigated immunological abnormalities in human IPH and attempted to produce experimental models of IPH in rabbits sensitized with extract of IPH or normal rabbit spleen. We examined the role of the spleen in this disease. In the peripheral blood of human IPH, we found a reduction in suppressor T lymphocyte activity, increase in the Leu3a/Leu2a or OKT4/OKT8 ratio and some autoantibodies, e.g., antinuclear antibody or antilymphocyte antibody. After splenectomy, these immunological abnormalities tended to normalize. Furthermore, we have experienced some IPH cases with autoimmune diseases. In animal experiment, we succeeded in producing models in rabbits resembling human IPH by repeat injection of IPH or normal rabbit spleen-extract and found elevation factors of the portal vein pressure in the mitochondrial and microsomal fractions of the fixed cells of the spleen. From these results, IPH may be etiologically associated with an immunological mechanism and the spleen may play an important role in this disease.

[The use of liposomes for a study of cAMP transport by lymphocyte membranes]

The liposomes with incorporated membranes of SC+ lymphocytes, confirmed by ELISA, were obtained. The membranes of this type of lymphocytes but not thymocytes were capable of 3H-cAMP transport into the liposomes. As anti-SC serum inhibited this process, the SC components of lymphocyte membrane may take part in it.

Binding of monoclonal antibodies and T cell effector function in vivo

The capacity of adoptively transferred CD8+ effector T cells to induce meningitis in immunosuppressed, or unsuppressed, recipients infected with lymphocytic choriomeningitis virus (LCMV) may be diminished by prior incubation of the lymphocytes with IgM monoclonal antibodies (MAbs) specific for CD8 or Thy1.2. The same is true, though to a lesser extent, for the further proliferation of donor T cells in the spleens of the immunosuppressed mice. This inhibition of cell mediated immunity can be overcome, at least for the unsuppressed recipients, by increasing the numbers of cells that are transferred, even though exposure to Mab+ complement abrogates all cytotoxic T cell activity in vitro. The LCM model thus provides a quantitative system for assessing the consequences of MAb binding for T cell trafficking and effector function in vivo.

Polymeric IgA antibody response to rabbit antithymocyte globulin in renal transplant recipients

Treatment of transplant recipients with heterologous antithymocyte globulin (ATG) can induce the production of antibodies to the ATG itself. Such responses have, however, not been fully defined in terms of the kinetics, class, and quantities of antibodies produced. We have studied these parameters in 32 renal transplant recipients who had received rabbit ATG as treatment for acute rejection episodes. Antibodies to rabbit IgG were detected in the sera of all patients; employing an enzyme-linked immunosorbent assay (ELISA), the majority of patients were shown to produce specific antibodies of the IgG, IgA, and IgM class. Anti-ATG antibodies were first detected 6-48 days after the initial injection of ATG and usually attained peak values within 23 days. The IgM and IgA responses decreased within 1-2 months, whereas the IgG response remained elevated for 2-12 months. Gel filtration studies indicated that the IgA and IgM antibodies directed to the rabbit ATG were polymeric. Furthermore, the polymeric IgA bound secretory component, indicating the presence of J chain. In 6 patients, circulating immune complexes that contained rabbit IgG were detected. The clinical symptoms and laboratory findings did not correlate with the production or quantities of the different classes of antibodies. Possible explanations for the prominent IgA response to intravenous injections of ATG are discussed.

Feto-maternal HLA compatibility does not have a major influence on human pregnancy except for lymphocytotoxin production

Several studies have supported the hypothesis that the maternal immune response to incompatible paternal HLA antigens present on the conceptus may influence pregnancy outcome. In order to relate feto-maternal histocompatibility directly to pregnancy course and characteristics, complete HLA-A, B and DR types were obtained from 132 healthy family groups consisting of mothers, fathers and neonates. The distribution of feto-maternal HLA compatibility was heavily skewed towards incompatibility, with 90% of fetuses being mismatched at 2 or 3 loci. There was no segregation distortion of paternal haplotypes, however, and the number of feto-maternal mismatches was close to that expected theoretically. More than 2% of the neonates were perfectly HLA-A, B and DR compatible with their mothers. The degree of feto-maternal HLA disparity showed no significant correlation with sex of neonate, birthweight, placental weight, maternal plasma alpha-fetoprotein or parity of the mother. Feto-maternal HLA disparity did, however, correlate significantly with maternal lymphocytotoxin production, even after allowance was made for parity (P less than 0.01). We conclude that feto-maternal HLA compatibility per se does not have a major influence on pregnancy outcome, and in particular is unlikely to predispose to spontaneous abortion; so an absence of antigen sharing between spouses experiencing recurrent spontaneous abortions should not be regarded in itself as a contraindication to offering immunotherapy to such couples.

Characteristics of the strongly Ia-positive cells in rat liver

The expression of MHC class II antigens (Ia) on rat liver non-hepatocytic cells were analysed by the Staphylococcus aureus rosette method using monoclonal antiserum to the common part of the class II molecules. Of the non-hepatocytic liver cell population, the passenger lymphocytes and monocytes were strongly anti-Ia binding but the most reactive were large mononuclear cells, morphologically macrophages. The characteristics of the strongly Ia-positive cells of rat liver were tested with different 'macrophage markers'. Of the macrophage-like cells, 55% were Ia-positive in the Staph. aureus rosette 84% had intracytoplasmic lysozyme, 100% of them were positive for alpha-naphthyl acetate esterase (ANAE) reaction, and 92% had Fc-receptors on the cell surface. As functional tests of macrophages, phagocytosis and adhesion were used: 79% of the cells were able to phagocytose antibody-coated human red cells and 56% of the cells adhered on glass. As most of the tested cells were positive for the markers the results demonstrate that the most antigenic component of rat liver has the characteristics of macrophages and thus the strongly Ia-positive cells are probably liver tissue macrophages (Kupffer cells).

Flow cytometric analysis of specific binding of soluble Ia by I-region restricted alloactivated T cells

An antigen binding assay has been developed for quantitation by flow cytometry of vesicular and soluble Ia binding by alloactivated T cells. Binding of stimulator membrane vesicles was detected by anti-Ly-6.2 or anti-Ia monoclonal antibodies coupled to fluorescent latex beads. Vesicle binding by an I-Ak specific A.TH anti-A.TL T cell line occurred via I-Ak molecules, in that (a) vesicles expressing I-Ak molecules bound much more effectively than vesicles of H-2b,q strains, and (b) inhibition of H-2k vesicle binding occurred with anti-I-Ak, but not anti-Kk, anti-Ek, or anti-Dk antibodies. T cell receptor/Ia interactions were directly studied by inhibition of H-2k vesicle binding by T cells with partially purified Ia glycoproteins. Inhibition of binding occurred via Ia molecules since (a) affinity column partially purified allogeneic I-Ak molecules inhibited binding much more effectively than syngeneic I-As molecules and (b) depletion of I-Ak but not Ek molecules in Iak containing glycoprotein fractions abrogated the inhibitory effect. The ability of this method to detect specific binding of soluble Ia with antigen activated T cells makes it a useful tool for studying interaction of membrane free major histocompatibility complex (MHC) products with native T cell receptor.

B-lymphocytes activation by the Fc region of IgG

Strong stimulation of DNA synthesis (up to 150-fold) and blast transformation can be induced in mouse spleen cells by Fc fragments of human IgG. The mitogenic response is optimal on day 5 of culture and is dependent on the concentration of Fc fragments with a sedimentation rate of 3-5S. Intact IgG is also stimulatory, but only when modified by heat aggregation, and produces only a 10-fold increase in [3H]thymidine uptake. The stimulation by aggregated IgG is dependent on the Fc portion, since aggregated (or soluble) Fab or F(ab')2 fragments are inactive. The results show that the response is T-cell independent and that it is a function of nylon wool adherent, surface Ig-positive, Fc receptor-bearing B lymphocytes. Fc fragments do not induce plaque-forming cells to human IgG in normal mouse spleen cell cultures, but rather trigger polyclonal antibody synthesis (anti-goat erythrocytes, anti-2,4,6-trinitrophenyl). It is postulated that the Fc region of antibodies plays a role in the regulation of the humoral immune response by triggering clonal expansion of B lymphocytes.

Platelet aggregation induced by antilymphocyte serum. 2. Two modes of the aggregation mechanism

The ability to inhibit the release reaction was found to correlate well with the ability to inhibit aggregation in washed human platelets exposed to antilymphocyte serum (ALS). However, the primary mechanism that contributes to ALS-induced aggregation in unwashed platelets appeared to be different from that found in washed platelets. Prostaglandin E1 and other release inhibitors were less effective in inhibiting aggregation in unwashed than in washed platelets. Salyrgan (mersalyl) in the presence of ALS or bovine fibrinogen produced an aggregation response in unwashed platelets that resembled the primary phase of aggregation. Two modes of the aggregation mechanism were evolved and are discussed.

Immunologic responses of graft recipients to antilymphocyte globulin: effect of prior treatment with aggregate-free gamma globulin

The immunologic response of graft recipients to antilymphocyte globulin has been studied. The clearance from the serum of (125)I-labeled antilymphocyte globulin was studied in 15 graft recipients previously treated with antilymphocyte globulin and in 4 control patients not previously treated with antilymphocyte globulin. The mean serum half-life of antilymphocyte globulin was 7.2 days in control patients, 3.8 days in 13 renal graft recipients, and 22 hr in 2 heart graft recipients. All but one of the antilymphocyte globulin-treated patients had rapid clearance. Patients treated with equine antilymphocyte globulin had rapid clearance of rabbit and goat antilymphocyte globulin as well as horse antilymphocyte globulin. All patients with rapid clearance of antilymphocyte globulin had circulating antibodies to xenogeneic gamma globulin. Two patients with rapid clearance of antilymphocyte globulin had circulating complexes of antilymphocyte globulin. Five renal graft recipients were treated with aggregate-free equine gamma globulin before antilymphocyte globulin therapy in an attempt to induce tolerance to xenogeneic gamma globulin. In these five patients neither rapid clearance of antilymphocyte globulin nor significant titers of circulating antibody to xenogeneic gamma globulin developed. The induction of tolerance to xenogenic gamma globulin may benefit patients treated with antilymphocyte globulin.