Current practice in bowel preparation for colorectal surgery: a survey of the members of the Association of Coloproctology of GB & Ireland

AIM

Recent meta-analyses have suggested that mechanical bowel preparation is not beneficial in patients undergoing colorectal resection. This study aimed to assess current surgical practice in the UK.

METHOD

Three hundred and ninety-eight members of the Association of Coloproctology of GB & Ireland were invited to complete an online survey to ascertain their current practice for bowel preparation.

RESULTS

One hundred and ninety-nine surgeons completed the survey, of whom 95 (48%) routinely performed laparoscopic resection. The proportions using full bowel preparation for open vs laparoscopic surgery were, respectively, 9.5%vs 16.8% for right hemicolectomy, 43.4%vs 40.2% for left hemicolectomy, 20.5%vs 22.5% for an abdominoperineal resection and 72.2%vs 63.6% for low anterior resection. Among the surgeons who participated, 13.6% changed their practice between doing the same procedure open and laparoscopically, 76% of surgeons routinely defunctioned a low anterior resection. Of these, 22% did not feel that full bowel preparation was necessary before formation of an ileostomy.

CONCLUSION

The study demonstrates that a large proportion of patients still receive full bowel preparation despite recent advice to the contrary.

Neointimal and tubulointerstitial infiltration by recipient mesenchymal cells in chronic renal-allograft rejection

BACKGROUND

Tissue remodeling depends on mesenchymal cells (fibroblasts and myofibroblasts) and is a prominent feature of chronic renal-transplant rejection. It is not known whether the mesenchymal cells that participate in remodeling originate locally or from circulating precursor cells.

METHODS

We obtained biopsy specimens of renal allografts from six male recipients of an allograft from a female donor, four female recipients of an allograft from a male donor, two male recipients of an allograft from a male donor, and two female recipients of an allograft from a female donor. All the allografts were undergoing chronic rejection. All but two specimens were obtained within six months after transplantation. We used immunohistochemical methods to identify mesenchymal cells with smooth-muscle alpha-actin and in situ hybridization to identify mesenchymal cells with Y-chromosome DNA.

RESULTS

No Y-chromosome bodies were identified in the case of the two renal-allograft specimens in which both the donor and the recipient were female. In the case of the two renal-allograft specimens in which both the donor and the recipient were male, approximately 40 percent of mesenchymal cells contained a Y-chromosome body. In the case of the six specimens in which the donor was female and the recipient was male, a mean (+/-SD) of 34+/-16 percent of mesenchymal cells in the neointima, 38+/-12 percent of such cells in the adventitia, and 30+/-7 percent of such cells in the interstitium contained the Y-chromosomal marker, indicating that they originated from the recipient rather than the donor. In the case of the four renal-allograft specimens in which the donor was male and the recipient was female, the respective values were 24+/-15 percent, 33+/-9 percent, and 23+/-8 percent, indicating a persistent population of donor mesenchymal cells.

CONCLUSIONS

The presence of mesenchymal cells of host origin in the vascular and interstitial compartments of renal allografts undergoing chronic rejection provides evidence that a circulating mesenchymal precursor cell has the potential to migrate to areas of inflammation.

Increased levels of GALbeta1-4GLCNACalpha2-6 sialyltransferase pretransplant predict delayed graft function in kidney transplant recipients

BACKGROUND

Galbeta1-4GlcNAcalpha2-6 sialyltransferase (ST6GalI) is an acute phase reactant whose release from cells can be induced by proinflammatory cytokines. Because patients with chronic renal failure have high circulating levels of proinflammatory cytokines, we hypothesized that patients on the renal transplant waiting list would have high circulating levels of ST6GalI, which might adversely affect post-transplant events.

METHODS

Levels of ST6GalI were measured in the serum of 70 patients immediately before renal transplant; these were correlated with posttransplant events, such as delayed graft function and rejection.

RESULTS

The mean serum level of ST6GalI was significantly higher in the patients (3162+/-97 U) than in 19 controls (2569 +/- 125 U; P<0.003). Patients who required dialysis posttransplant for treatment of delayed graft function (n=20) had significantly higher levels of ST6GalI pretransplant (3735+/-228 U) than patients (n=50) who did not require dialysis (2933+/-83 U; P<0.0001). In a multivariate analysis the ST6GalI level and cold ischemic time were found to be independent risk factors for the development of delayed graft function.

CONCLUSIONS

ST6GalI levels are high in renal failure patients awaiting a renal transplant and may be a risk factor for the development of delayed graft function. The assessment and perhaps modulation of a potential transplant recipient's ST6GalI systemic level may be beneficial.

Anti-HLA antibodies after solid organ transplantation

We have cited more than 23 studies showing that de novo development of anti-HLA antibodies is associated with increased acute and chronic rejection and decreased graft survival in kidney, heart, lung, liver, and corneal transplants. Antibodies to both HLA class I and class II antigens seem to be detrimental. Antibodies of the IgG isotype and possibly the IgM isotype were clinically relevant. Most studies showed that donor-specific antibodies were associated with rejection and graft loss. Therefore, HLA antibodies provide a clinical readout for patient alloreactivity that may have the ability to distinguish graft dysfunction due to immunologic and nonimmunologic causes. Antibody may act as a critical trigger for rejection of allografts and may serve as an early indicator of a slowly smoldering chronic rejection that is not manifested at a given time by biochemical measures such as serum creatinine levels. The effectiveness of various drugs on chronic rejection should be evaluable by their effects on HLA antibody production. We predict that recently developed ELISA and flow cytometry techniques using purified HLA antigen will increase the clinical relevance of posttransplantation HLA antibody monitoring by (1) allowing the detection of low levels of donor antibody; (2) easily distinguishing the isotype and target (HLA class I or class II) of the antibodies; and (3) correlating the antibody with specific graft pathology.

Immune-activation gene expression in clinically stable renal allograft biopsies: molecular evidence for subclinical rejection

BACKGROUND

A significant percentage of biopsies from stable, well-functioning renal allografts have histologic findings consistent with acute rejection or borderline rejection. The implication of this finding is not yet fully understood. We analyzed immune-activation gene transcripts in stable protocol biopsies to determine the extent of immunologic activity of graft-infiltrating cells in this setting. Histologic classification of the biopsies was based on the Banff criteria. To emphasize that the tissue samples were procured from grafts with no clinical evidence of impaired function, we interjected the term "subclinical" into the Banff terminology. This produced three histologic categories: normal, borderline subclinical rejection, and acute subclinical rejection.

METHODS

We used competitive template polymerase chain reaction techniques to quantify transcript amounts for the constant region of the T-cell receptor beta chain; the cytokines, tumor necrosis factor alpha, interleukin (IL)-1beta, transforming growth factor beta, interferon gamma, IL-2, IL-4, IL-10, and IL-15; and the cytotoxic T lymphocyte effector molecules, granzyme B, perforin, and Fas ligand.

RESULTS

We found that histologically normal biopsies were typically devoid of gene transcripts or had very low amounts. Conversely, biopsies with acute subclinical rejection by histologic examination had heightened amounts of transcripts for many of the genes assayed. Borderline subclinical rejection samples showed an intermediate amount of expression.

CONCLUSIONS

These results demonstrate that histologic features of rejection are often accompanied by enhanced expression of pro-inflammatory gene transcripts, despite the absence of clinically overt graft dysfunction. As this state of subclinical rejection could prove detrimental to long-term graft function, a role for surveillance biopsies of stable grafts with intent to treat subclinical rejection should be considered.

Protocol biopsies in renal transplantation: research tool or clinically useful?

Early protocol biopsies of stable, well functioning renal allografts reveal a high prevalence of clinically unsuspected acute and chronic pathology. It is becoming increasingly apparent that these histopathological findings are both pathogenic and predictive of long-term allograft outcome. Therefore, protocol biopsies may be required for optimal post-transplant surveillance until non-invasive methods to detect allograft inflammation are developed.

Matching for private or public HLA epitopes reduces acute rejection episodes and improves two-year renal allograft function

BACKGROUND

The current role of HLA matching in renal transplantation is controversial. Public HLA epitope matching has been suggested to be as advantageous as private HLA matching, with the added benefit of increasing recipients' access to well-matched grafts.

METHODS

In this single-center study of 105 renal transplant recipients, we examined the association of HLA matching with early (0-3 months) and late (4-6 months) rejection episodes (RE), as well as renal allograft function up to 2 years after transplant.

RESULTS

Poor HLA-DR, but not HLA-A or -B, matching was associated with early RE (0 DR matches, RE=2.7+/-0.19, 1 DR match, RE=2.37+/-0.18, vs. 2 DR matches, RE=1.5+/-0.38; P < 0.01). In contrast, poor HLA-B, but not HLA-A or -DR, matching was associated with late rejections (0 HLA-B matches, RE=1.1+/-0.51 vs. 1-2 HLA-B matches, RE=0.51+/-0.1; P < 0.004). HLA-B matching was also associated with a significantly lower serum creatinine (SCr) level at 24 months (0 HLA-B matches, SCr=178+/-20 micromol/L vs. SCr=132+/-6 micromol/L for 1-2 HLA-B matches; P < 0.025). Matching for 10 supertypic HLA-A and -B cross-reactive groups was associated with reduced late graft rejection (0-2 residue matches, RE=1.15+/-0.18 vs. RE=0.62+/-0.12 for 3 to 7 residue matches; P < 0.013) as well as a significantly lower SCr level at 24 months (0-2 residue matches, SCr=205+/-29 micromol/L vs SCr=131+/-6 micromol/L for 3 to 7 residue matches; P < 0.001) after transplantation.

CONCLUSIONS

HLA-DR matching was associated with a reduced frequency of early rejection episodes, whereas HLA-B or residue/cross-reactive group matching was associated with a reduced frequency of late rejection episodes and improved graft function at 2 years.

Antibodies to interferon-alpha in treated cancer patients: incidence and significance

Antibodies to interferon-alpha (IFN-alpha) are found in some patients being treated with this cytokine. In studies in which two recombinant IFN-alpha preparations were directly compared in cancer patients, those given IFN-alpha2a were found to have neutralizing antibodies in their serum significantly more often than those given IFN-alpha2b (p <0.001). Patients who develop neutralizing antibodies are more likely to have a clinical relapse and to become resistant to further treatment with at least the IFN preparation initially used for their treatment. In 10 studies in cancer patients, such an outcome was found in 63% of those who developed antibodies but in only 13% of those who did not. These data are tabulated.

Low frequency of infiltrating cells intensely expressing T cell cytokine mRNA in human renal allograft rejection

Immunosuppressive drugs used in clinical transplantation block cytokine mRNA transcription in vitro, but clinical rejection episodes are common. An understanding of what cytokine message is transcribed would be helpful in determining what contributes to the success of immunosuppression and provide directions for further research aimed at targeting specific cytokines. Previous studies have examined cytokine mRNA in rejecting solid organ biopsies by the reverse transcriptase polymerase chain reaction (RT-PCR) with variable results. We used nonradioactive in situ hybridization with cytokine-specific riboprobes to determine the frequency of cells expressing cytokine mRNA in the allograft infiltrate. Kidney biopsies were obtained from patients receiving protocol biopsies and with clinical evidence of rejection. Fourteen biopsies with a pathologic diagnosis of rejection were studied. Eight showed no cytokine staining, 2 expressed IL-2, and 3 expressed IL-4 and IFN-gamma. The positive cells were present at a low frequency (mean 2, range 1-5 per 10 high-power fields). The proportion of kidney biopsies expressing detectable message for interleukin-2 (IL-2), interleukin-4 (IL-4), and interferon-gamma (IFN-gamma) by in situ hybridization were similar to those reported using RT-PCR. The novel finding is that these cytokines are expressed in a few strongly positive cells in the allograft infiltrate. The vast majority of infiltrating cells are negative. This suggests that either the biopsies were performed when cytokine message was not expressed at a high level or that in human allograft recipients the sustained expression of the cytokines IL-2, IL-4, and IFN-gamma may not be necessary for graft rejection.

Increased production of tumor necrosis factor activity by hemodialysis but not peritoneal dialysis patients

The production of tumor necrosis factor alpha (TNF alpha) activity by peripheral blood mononuclear cells (PBMC) was determined in uremic patients on chronic hemodialysis (HD; n = 27), continuous ambulatory peritoneal dialysis (CAPD; n = 19), and in patients with chronic renal failure who were not yet on dialysis (CRF-ND; n = 18). In the HD group blood was taken immediately prior to and immediately following an HD session utilizing a cellulose acetate dialyzer. Post-HD PBMC spontaneously (i.e. in serum free media) produced significantly more TNF alpha activity than the PBMC of all other patient groups as well as those of the normal controls (n = 41) (p < 0.003). Post-HD PBMC produced significantly more TNF alpha activity than pre-HD PBMC both spontaneously and in the presence of nonuremic sera (p < 0.003). PBMC prior to HD also produced significantly more. TNF alpha activity than CAPD PBMC and normal PBMC in the presence of autologous heat inactivated sera (p < 0.03). Under some culture conditions (i.e. in the presence of nonuremic sera) normal PBMC produced significantly (p < 0.003) more TNF alpha activity than CAPD PBMC. Finally, a positive correlation was found between PBMC TNF alpha activity and age for HD patients (r = 0.7, p < 0.004) but not for CAPD or CRF-ND patients. These findings suggest that PBMC of HD but not CAPD or CRF-ND patients are chronically stimulated to produce TNF alpha activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Production of tumor necrosis factor alpha and hemodialysis

The production of TNF alpha by peripheral blood mononuclear cells (PBMC) was determined in 18 hemodialysis (HD) patients. Blood was taken from each patient before and after an HD treatment. Both pre- and post-HD PBMC produced significantly more TNF alpha than controls (TNF alpha units/ml; mean +/- SEM; controls 3.1 +/- 0.7; pre-HD 9.7 +/- 3.9; post-HD 19.8 +/- 7.7, p < 0.05). In addition, post-HD PBMC produced significantly more TNF alpha than pre-HD PBMC suggesting that the HD procedure itself may activate cytokine production. This was true when PBMC were cultured in serum free medium as well as on culture with non-HD sera (human AB) and autologous sera. A positive correlation was also found between the production of TNF alpha and age in HD patients (r = 0.58; p < 0.01). Finally, normal PBMC cultured in post-HD sera produced significantly less TNF alpha than when cultured in the same sera pre-HD (p < 0.02). These findings suggest that PBMC of HD patients are chronically stimulated to produce TNF alpha which may contribute to some of the short-term and long-term complications of HD.

A multicenter study to evaluate a novel assay for quantitation of soluble interleukin 2 receptor in renal transplant recipients

The clinical utility of monitoring soluble interleukin 2 receptor (sIL-2R) as an indicator of immune stimulation in renal transplant patients was evaluated in a retrospective study at 3 centers. Serum samples (n = 2360) were obtained from 86 (17 living related donor, 69 cadaver) transplant recipients. The patients had received either triple therapy (n = 35) or antilymphocyte antibody induction therapy followed by triple therapy (n = 51). The mean period of postoperative observation was 118 days (range, 6-349 days). Serum sIL-2R concentrations were quantitated by an automated microparticle enzyme immunoassay (MEIA) (Abbott Diagnostics) in which sIL-2R was captured by 7G7/B6 monoclonal antibody-coated microparticles and detected by an immunospecific rabbit antihuman sIL-2R-alkaline phosphatase conjugate. A distinct advantage of the technique was rapid turn-around time: 1-24 results were obtained in less than 50 min. Cyclosporine trough concentrations were determined by radioimmunoassay or high-performance liquid chromatography. Diagnosis of rejection was established by clinical and histological criteria. The mean sIL-2R concentration in patients receiving antilymphocyte antibody induction therapy increased from 3486 +/- 1729 U/ml (+/- SD) at the time of transplant to a maximum of 7395 +/- 7101 U/ml on the third day posttransplant; this increase was not observed in patients receiving triple therapy (P less than 0.0001). By the sixth day of posttransplant, there were no differences in sIL-2R levels in the two groups. Fifty rejection episodes were observed in 29 patients on triple therapy. The mean sIL-2R concentration rose from 3022 U/ml at the data point prior to rejection to 3524 U/ml at the time of rejection. Thirty-four rejection episodes were observed in 26 patients receiving induction therapy. The mean sIL-2R concentration was 3015 U/ml at the data point prior to rejection and 4815 U/ml at the time of rejection. The sIL-2R concentrations began increasing earlier and rose higher in rejecting patients who received induction therapy than in those receiving triple therapy. Early posttransplant sIL-2R levels increased significantly more in cadaver recipients than in LRD recipients, reaching a maximum on day 2 posttransplant (P less than 0.001). Prerejection sIL-2R concentrations were significantly lower in LRD recipients than in cadaver recipients (2248 U/ml vs. 4290 U/ml, P less than 0.02), as were sIL-2R levels at the time of diagnosis of rejection (2800 U/ml vs. 4832 U/ml, P = 0.01). The mean sIL-2R level in stable long-term graft recipients was 2110 U/ml, with approximately 90% of values less than 3000 U/ml.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunological monitoring in cyclosporine-treated patients

The immunosuppressive action of cyclosporine (CsA) in vivo is thought to primarily involve its inhibitory effect on lymphokine production by T lymphocytes. Most efforts to assess immunosuppression in CsA-treated patients have concentrated on measuring some aspect of activated T cell function. These have included monitoring of lymphocyte subsets and the appearance of activated T cell markers, assaying the production of lymphokines and the direct measurement of lymphokines in serum and urine, and most recently measurement of soluble interleukin-2 receptor (SIL2R). Using a new microparticle enzyme immunoassay (MEIA) in a preliminary study of 12 CsA-treated renal transplant recipients, we found significant increases in serum SIL2R levels in patients with rejection and we conclude that MEIA may have some use in the monitoring of CsA-treated patients.

Immunosuppressive activity of cyclosporine metabolites compared and characterized by mass spectroscopy and nuclear magnetic resonance

Eight cyclosporine (CsA) metabolites were isolated from the urine of renal-transplant patients by high-pressure liquid chromatography. Structure and purity of the metabolites were assessed by fast atomic bombardment/mass spectroscopy, by proton nuclear magnetic resonance (NMR), and, when the quantity of metabolites permitted, by 13C-NMR. The immunosuppressive activities (I) of the metabolites were tested in three separate in vitro systems: primary and secondary mixed lymphocyte reactions as well as by a mitogen-stimulated system. The I, as measured by comparing the concentration of each metabolite required for 50% inhibition of incorporation of [3H] thymidine, varied among the assay systems, as did the ranking of I among the test systems. In general, the I of most metabolites in all assay systems were less than 10% of that for CsA. Metabolites with single modifications exhibited the greatest I; e.g., that of M-17 was congruent to 16% of that of CsA (potency ratio 0.16) in a secondary mixed lymphocyte reaction. The significance of these findings in relation to therapeutic monitoring of CsA is discussed.

Immunosuppressive activity of cyclosporine metabolites compared and characterized by mass spectroscopy and nuclear magnetic resonance

Eight cyclosporine (CsA) metabolites were isolated from the urine of renal-transplant patients by high-pressure liquid chromatography. Structure and purity of the metabolites were assessed by fast atomic bombardment/mass spectroscopy, by proton nuclear magnetic resonance (NMR), and, when the quantity of metabolites permitted, by 13C-NMR. The immunosuppressive activities (I) of the metabolites were tested in three separate in vitro systems: primary and secondary mixed lymphocyte reactions as well as by a mitogen-stimulated system. The I, as measured by comparing the concentration of each metabolite required for 50% inhibition of incorporation of [3H] thymidine, varied among the assay systems, as did the ranking of I among the test systems. In general, the I of most metabolites in all assay systems were less than 10% of that for CsA. Metabolites with single modifications exhibited the greatest I; e.g., that of M-17 was congruent to 16% of that of CsA (potency ratio 0.16) in a secondary mixed lymphocyte reaction. The significance of these findings in relation to therapeutic monitoring of CsA is discussed.

Inhibition of cytokine production by cyclosporine A and G

Cyclosporine G (CsG) is an analogue of CsA that may not have the nephrotoxicity of CsA. Not much is known about the relative immunosuppressive activity of CsG compared with CsA in humans. For this reason we compared the effects of CsA and CsG on in vitro interferon gamma production by mitogen and alloantigen-stimulated peripheral blood mononuclear cells from normal individuals. We also investigated the effects of CsA and CsG on the production of lymphotoxin (LT) and tumor necrosis factor (TNF) activity, as these cytokines have been implicated in transplant rejection. Both CsA and CsG showed very similar dose-dependent inhibition of IFN-G and LT/TNF activity (IC50 CsA for IFN-G = 8.0 ng/ml, for LT/TNF = 9.5 ng/ml; IC50 CsG for IFN-G = 13.0 ng/ml, for LT/TNF = 13.0 ng/ml). Maximum suppression was seen if the drugs were added at culture initiation and suppression was reduced if the drugs were added 24 hr later. Both CsA and CsG showed significant dose- and time-dependent inhibition of IFN-G production in 2 degrees MLC. LT/TNF activity was suppressed by CsA and CsG in 2 degrees MLC, which was also dose- and time-dependent. These results suggest that CsG has an immunosuppressive profile similar to that of CsA and may therefore be useful in clinical situations where CsA nephrotoxicity is a problem.

Lymphokine production in rheumatoid arthritis and systemic lupus erythematosus

The production of interferon (IFN) by peripheral blood lymphocytes from patients with rheumatoid arthritis (RA) and of IFN and interleukin 2 (IL-2) in systemic lupus erythematosus (SLE) was compared with that of healthy controls. Patients with SLE showed a significant reduction in IL-2 production compared to controls if the PBL were irradiated before mitogen stimulation. No patient with RA or SLE studied had impaired IFN production regardless of disease activity and the IFN produced was always IFN-gamma in type. We conclude that there is an abnormality in IL-2 production in SLE but there is no abnormality in IFN-gamma production in either RA or SLE.

Interleukin 2, interferon, and lymphotoxin in renal transplant recipients

The immunosuppressive action of cyclosporine in transplantation (Tx) is thought to be due to its potent inhibition of lymphokine production by T cells. Several studies have shown a decrease in interleukin 2 (IL-2) and interferon-Gamma (IFN-G) production of renal Tx recipients on CsA treatment and have suggested that increases in lymphokine production can be correlated with rejection episodes. In this study we measured IL-2, IFN-G, and lymphotoxin (LT) production by mitogen-stimulated peripheral blood lymphocytes in eight renal Tx recipients before and at various times after Tx. IL-2 production was significantly (P less than 0.05) decreased by one week post-Tx compared with pre-Tx and normal levels. IFN-G production was significantly (P less than 0.05) decreased by one week post-Tx, after which time it returned to normal. LT production was not decreased post-Tx compared with pre-Tx or normal levels. Lymphokine production was measured every 48-72 hr in the first month post-Tx, when we failed to detect any correlation between increases in production in any of the three lymphokines and rejection episodes. A further group of patients were studied in whom the production of all three lymphokines was measured at the time of diagnosis of rejection and after treatment for rejection. In only 3/5 patients did IL-2 production decrease with a return to stable graft function, while IFN-G production did not alter in these patients. Interestingly LT production increased significantly (P less than 0.05) after treatment. We conclude from these studies that the usefulness of lymphokine determinations for the diagnosis of allograft rejection remains unproved.

Characterization of synovial T lymphocytes in rheumatoid arthritis. I. Production of IL-2 dependent T cell clones from synovial fluid and peripheral blood

Lymphocytes obtained from the peripheral blood (PBL) or synovial fluids (SFL) of patients with rheumatoid arthritis (RA) or other inflammatory joint diseases were compared with the PBL from normal individuals, by cloning under limiting dilution conditions in the presence of interleukin 2 (IL-2). The precursor frequency estimates of IL-2 responsive cells from these sources did not differ appreciably. However there were marked differences in the surface marker phenotypes of the clones derived from the PBL as compared to SFL. There was a predominance of OKT4-8+ cells in SFL from RA and non RA donors with inflammatory joint disease while PBL from all sources showed a marked prevalence of OKT4+8- cells. Comparison of precursor frequencies in the presence of PBL and SFL indicated that there were variations in the capacities of the SFL and PBL IL-2 dependent cells to grow on these fillers. SFL derived cells grew equally well on PBL or SFL filler, while PBL clones grew efficiently only on PBL fillers. Collectively these results indicate that there are marked differences in the surface phenotypes and growth requirements of IL-2 responsive SFL as compared to PBL.

Interleukin 2 production and responsiveness in active and inactive rheumatoid arthritis

The interleukin 2 (IL-2) production and responsiveness of peripheral blood lymphocytes from patients with rheumatoid arthritis (RA) with active or inactive disease was compared with that of normal control donors. IL-2 production was assessed using a cellular interleukin assay in which an IL-2 dependent cell line was cocultured with varying numbers of irradiated IL-2 producing lymphocytes from the different donor sources. Cells from patients with active disease showed a significantly different pattern of IL-2 production from that of control or inactive RA patients in that a lower number of cells supported growth of the IL-2 dependent cell line. In one patient this shift in pattern was shown to correlate with change in disease activity. Lymphocyte responsiveness to IL-2 as determined by limiting dilution analysis did not differ significantly between the different groups. The results are consistent with a hyperproduction of IL-2 in RA during active disease.

Studies on the mechanism of suppression of experimental allergic encephalomyelitis induced by myelin basic protein-cell conjugates

The mechanism of suppression of experimental allergic encephalomyelitis (EAE) induced in Lewis rats by pretreatment with myelin basic protein (MBP) coupled to syngeneic spleen leukocytes (SL) was examined. Studies on the kinetics of the tolerance induction showed that pretreatment with MBP-SL suppressed EAE if given 7 but not 3 days before the disease-inducing injection of MBP in Freund's complete adjuvant. Treatment with cyclophosphamide 48 hr before administration of MBP-SL completely abolished the suppression of EAE. Transfer of lymph node and spleen cells from MBP-syngeneic erythrocyte conjugate (MBP-RBC) but not MBP-SL-pretreated rats resulted in suppression of disease in recipients subsequently given a disease-inducing injection of MBP. Administration of MBP coupled to SL from the histocompatible rat strain F344 resulted in suppression of the MBP-induced proliferative response of spleen cells from Lewis rats which had been given a disease-inducing injection of MBP. Taken together these results are consistent with the suppression of EAE induced by MBP-SL being mediated by suppressor T cells.

The suppression of experimental allergic encephalomyelitis in Lewis rats by treatment with myelin basic protein-cell conjugates

Pretreatment of Lewis rats with guinea pig (GP) myelin basic protein (MBP) coupled to syngeneic spleen leukocytes (SL) suppressed the subsequent induction of experimental allegic encephalomyelitis (EAE) with GP-MBP in Freund's complete adjuvant. The degree of suppression correlated positively with the amount of antigen coupled to the SL. GP-MBP coupled to syngeneic red blood cells (RBC) also resulted in suppression of EAE and the extent of the suppression was related to the dose of cells. These regimens of pretreatment also resulted in a decrease in the in vitro lymphocyte proliferative response to GP-MBP and in the extent of perivascular cuffing in the spinal cord. No decrease in the anti-MBP antibody response was detected in rats pretreated with either GP-MBP-SL or GP-MBP-RBC conjugates. Transfer of lymph node cells from rats pretreated with GP-MBP-RBC resulted in a decrease in disease severity in recipients. It is concluded that prior administration of MBP-cell conjugates is an effective way of suppressing the symptoms of EAE.