Randomised clinical trial: herbal extract HMPL-004 in active ulcerative colitis - a double-blind comparison with sustained release mesalazine

BACKGROUND

Andrographis paniculata is an herbal mixture used to treat inflammatory diseases. An extract of the herb, HMPL-004, inhibits TNF-α and IL-1β, and prevents colitis in animal models.

AIM

To determine the efficacy and safety of HMPL-004 in patients with mild-to-moderate ulcerative colitis.

METHODS

A randomised, double-blind, multicentre, 8-week parallel group study was conducted using HMPL-004 1200 mg/day compared with 4500 mg/day of slow release mesalazine (mesalamine) granules in patients with mild-to-moderately active ulcerative colitis. Disease activity was assessed at baseline and every 2 weeks for clinical response, and at baseline and 8 weeks by colonoscopy.

RESULTS

One hundred and twenty patients at five centres in China were randomised and dosed. Clinical remission and response were seen in 21% and 76% of HMPL-004-treated patients, and 16% and 82% of mesalazine-treated patients. By colonoscopy, remission and response were seen in 28% and 74% of HMPL-004-treated patients and 24% and 71% of mesalazine-treated patients, respectively. There was no significant difference between the two treatment groups.

CONCLUSION

HMPL-004 may be an efficacious alternative to mesalazine in ulcerative colitis.

Regulation of the contact sensitivity response to urushiol with anti-urushiol monoclonal antibody ALG 991

The objective of the studies was to demonstrate that the contact sensitivity (CS) response to poison ivy/oak could be downregulated following treatment with a monoclonal antibody (mAb) reacting with the allergen urushiol. Conjugation of urushiol and its synthetic analogue 3-n-pentadecylcatechol (PDC) to N-acetylcysteine yielded hydrosoluble derivatives which induced humoral immune responses in BALB/c mice. Hybridomas secreting monoclonal antibodies (mAbs) reacting with urushiol and PDC were generated by fusion of B lymphocytes from immunized mice with mouse myeloma P3NS0 cells. The specificity of mAb ALG 991 (IgM isotype) was defined by inhibition of antibody binding by PDC analogues. This demonstrated that mAb ALG 991 reacted with the catechol moiety of urushiol, the region of the allergen being critically important in the induction of contact dermatitis. The CS response to urushiol in BALB/c mice was suppressed by stimulation with mAb ALG 991 and the role of sensitized T cells, including suppressor T cells, has been considered. Suppression of CS was most effective with low doses (1 microg) of mAb incorporated into a vaccine with Freund's adjuvant. This treatment suppressed CS responses in BALB/c mice already sensitized to urushiol.

Measurement of murine IgE antibody responses to dust mite allergens by in vitro assay

In an analysis of murine immune responses to the dust mite allergen Der p 1, treatment with purified allergen induced a significant increase in the level of circulating IgE immunoglobulin (from less than 100 ng/ml in normal mice to 1,350 ng/ml in mice receiving the allergen). Even so, specific IgE antibodies binding to purified Der p 1 were not detected in a conventional ELISA, and the major response appeared to be the induction of high titre IgG antibodies. Specific circulating murine IgE antibodies were however detected using the following assay format: murine IgE was captured to anti-murine IgE antibody coated wells; Der p 1 was added and bound by immobilized anti-Der p 1 IgE antibodies; the captured Der p 1 was then detected by the addition of monoclonal IgG antibodies against Der p 1 and these antibodies were measured by the addition of anti-murine IgG antibody-enzyme conjugate with which colour development is produced after substrate addition. This assay establishes a procedure to measure circulating anti-Der p 1 IgE antibodies which are present together with competing high titre IgG anti-Der p 1 antibodies.

A phase II study of effect of addition of trichosanthin to zidovudine in patients with HIV disease and failing antiretroviral agents

Patients infected with HIV, including those with AIDS-related complex and AIDS, and failing treatment with antiretroviral agents such as zidovudine, have been evaluated following addition of trichosanthin to the antiretroviral agent regimen. This ribosomal inhibitory protein is specifically cytotoxic for HIV-infected macrophages and lymphocytes. Ninety-three patients were treated with trichosanthin, using a schedule of weekly, then monthly, intravenous injections of 1.2 mg of drug in combination with antiretroviral agents, usually zidovudine. Side effects included myalgias, fevers, mild elevation in liver function tests, and mild-moderate anaphylactic reactions, which respond well to therapy with steroids and/or benedryl. Reversible mental status changes were noted in two patients, both receiving concomitant therapy with ddI. Clinical responses to trichosanthin treatment were monitored primarily by changes in laboratory parameters, particularly levels of CD4+ T lymphocytes. In the total population evaluated for efficacy (85 patients) there was a significant increase in CD4+ cell levels after initiation of trichosanthin therapy. A second analysis performed on 72 patients measured the rate of change of CD4+ cells during therapy, using an "area under the curve" analysis. During therapy there was a median increase of 1.2 cells/mm3/month. In patients in the top 25th percentile, this increase was greater than 8.4 cells/mm3/month. In 59 of the 72 patients, responses could also be monitored by comparing the rate of loss of CD4+ cell levels on antiretroviral agents (zidovudine or ddI) alone, during the year prior to initiation of trichosanthin, to the rate of change when trichosanthin was added to the treatment regimen. During the period before trichosanthin treatment (311 +/- 11.7 days) the median loss of CD4+ cells was 6.91 cells/mm3/month. Addition of trichosanthin to the treatment regimen resulted in a median gain of 1.1 CD4+ cells/mm3/month.

Suppression of antibody responses to ricin A chain (RTA) by monoclonal anti-RTA antibodies

Balb/c mice treated with an immunotoxin constructed by conjugation of murine monoclonal antibody 791T/36 via a disulfide linker to ricin A chain generate a pronounced antibody response to peptide epitopes on ricin A chain. Monoclonal anti-RTA antibodies which recognize peptide epitopes have been developed and these have been used to down-regulate anti-RTA antibody responses in 791T/36-RTA immunotoxin-treated Balb/c mice. Of the five MAB tests, two (608/7 and 596/134) proved most effective, inhibiting anti-RTA antibody formation by up to 73%. MAB treatment was effective when initiated up to 3 days after immunotoxin treatment. Pharmacokinetic studies with 791T/36-RTA have shown that the immunotoxin is rapidly eliminated from the circulation, with no more than 4% remaining in blood after 24 hr. It is proposed that the down-regulation of anti-RTA antibodies is effected by MAB interfering with antigen processing.

Neurological reactions in HIV-infected patients treated with trichosanthin

Trichosanthin is a ribosome-inactivating protein that is being studied as a possible treatment for patients infected with human immunodeficiency virus (HIV). We report the clinical and pathological features in two patients who experienced neurological reactions to trichosanthin. Both patients were neurologically asymptomatic prior to treatment but developed coma and multifocal neurological deficits after treatment. Neuropathological examination revealed regions of severe, multifocal necrosis with histiocytic infiltrates. These reactions to trichosanthin may be mediated by soluble factors released by HIV-infected macrophages.

Multiple chemical sensitivities: a practicing clinician's point of view. Clinical and immunologic research findings

The multiple chemical sensitivities syndrome is a symptom complex characterized by emotional depression, short-term memory loss, acquired intolerance to environmental agents such as aerosolized petrochemicals and foods, and alteration in metabolic rate associated with increased body mass. This syndrome can be caused by multiple etiologic agents. With careful evaluation, it is rare that a causal agent can not be identified in this syndrome. Our treatment regimens include combinations of diet and environment control as well as antiviral, antifungal, and immune modulator therapy. We find that the majority of patients can, through time and appropriate treatment, be restored to a normal and productive lives.

Endocytosis of immunotoxin-791T/36-RTA by tumor cells in relation to its cytotoxic action

Ricin A chain immunotoxin constructed with monoclonal antibody 791T/36, which recognizes a tumor associated glycoprotein Mr 72,000 antigen present on sarcomas and colon and ovarian cancer cells, is cytotoxic for cell lines from tumors expressing this antigen. Incubation of sarcoma 791T cells with immunotoxin for only 5 min is sufficient to produce greater than 95% inhibition of tumor cell growth. Papain treatment of these cells to remove immunotoxin from the cell surface indicated that the cell surface acts as a reservoir for continued internalization of immunotoxin over several hours, but even so, 50% inhibition of cell survival was produced over a 2- to 3-h period. Analysis of the rate of endocytosis demonstrated that 30-50% of cell bound immunotoxin was internalized over a 180-min period. This was primarily dictated by the antibody moiety, regardless of the degree of conjugation to ricin A chain. This rate is much slower than that of other cell surface ligands such as transferrin. Cell cytosol acidification experiments were performed to determine whether this immunotoxin was internalized by clathrin coated pits, which is relatively rapid, or by smooth pits, which is slower, and the results indicated the latter mechanism is almost exclusively used. Intracellular trafficking of antibody 791T/36, conjugated to human serum albumin-tetramethylrhodamine was investigated by flow cytometry. The movement of the conjugate into the lysosomal compartment was delayed so that degradation products were only detected after a lag phase of 30-60 min. The lack of potentiator dependence of 791T/36 immunotoxin is in keeping with these findings.

Rationale for clinical use of immunotoxins in cancer and autoimmune disease

Immunotoxins constructed by conjugating monoclonal antibodies to plant and bacterial toxin molecules are being evaluated clinically for the treatment of cancer and as immunosuppressive agents in treating autoimmune diseases. Immunoconjugates constructed with ricin A-chain and in certain indications, whole ricin have been most extensively investigated. The experience with these immunotoxins has highlighted issues to be dealt with in order to improve therapeutic efficacy. Immunotoxins containing ricin A-chain conjugated to monoclonal antibody reacting with the CD5 molecule on T lymphocytes has proved most efficacious in treating acute graft versus host disease (aGvHD) in patients receiving bone marrow transplants as part of a regimen of high dose chemotherapy in leukaemias and lymphomas. This involved immunotoxin used after the onset of a GvHD or prophylactically to reduce the development of the condition. Immunotoxin treatment of leukaemias and lymphomas is also showing promise with clinical responses being observed. In comparison, treatment of solid cancers such as colorectal cancer and malignant melanoma has not yet proved effective. Factors to be resolved in order to improve treatment include better pharmacokinetic properties of immunotoxins, improved tumour penetration and the use of antibody cocktails to accommodate antigenic heterogeneity of tumours.

A phase I/II study of trichosanthin treatment of HIV disease

Trichosanthin, a ribosomal inhibitor protein, blocks HIV replication in lymphocytes and macrophages. This agent was used to treat 51 patients with advanced HIV disease in a dose-escalation study in which three injections were administered over a 9-21-day period in a dose range of 10-30 micrograms/kg per injection. The maximum tolerated dose was estimated to be 30 micrograms/kg. Reversible but severe fatigue and myalgias were the major dose-limiting side-effects; mild leucocytosis and elevations in serum transaminases were noted and were reversible. Non-dose-related reversible mental status changes were seen in six patients and were considered to be associated with the drug. This was usually manifest as dementia, but progressed to coma in two patients. This reversed, but the sequelae resulted in death in one patient. Decreases in serum p24 antigen levels were noted 1 month after the first infusion in 10 of 18 patients who entered the study with elevated levels; one converted to negative. Values usually remained low to the end of the study period (2 months). In those patients with CD4+ cell levels greater than 50 x 10(6) cells/l significant decreases in sedimentation rate and increases in CD4+ cell numbers were also noted. These changes were found at all dose levels but only in patients receiving three infusions.

Use of an anti-pan T-lymphocyte ricin a chain immunotoxin in steroid-resistant acute graft-versus-host disease

Acute steroid-resistant graft-versus-host disease (AGVHD) after allogeneic bone marrow transplantation is frequently fatal. A new treatment for this T-lymphocyte-mediated condition uses an immunotoxin, H65-RTA, comprised of a monoclonal antibody that recognizes the CD5 lymphocyte differentiation antigen coupled to ricin A chain, a cytotoxic enzyme that inhibits protein synthesis. The safety and efficacy of this lymphocyte-targeted immunotoxin was evaluated in patients with severe AGVHD in a phase I-II dose escalation study with group expansion at the two middle doses. Thirty-four patients received up to 14 daily intravenous infusions of the immunotoxin. The principal side effects were constitutional symptoms such as fatigue and myalgias, and hypoalbuminemia with weight gain was seen at all doses. Thirty-two patients were evaluated for improvement or resolution of disease. Durable complete or partial responses were not dose-related and were seen in 16 patients. Skin GVHD had the highest incidence of response (73%), although improvement or resolution in gastrointestinal tract (45%) and liver (28%) GVHD was also noted. Survival in responding patients was significantly prolonged at all times as compared with those with no response (P = .03). Treatment was associated with a rapid decrease in peripheral blood T lymphocytes, which persisted for greater than 1 month after therapy. Anti-immunotoxin antibodies were seen in 6 of the 23 patients tested; these were of low titer and did not block immunotoxin binding to T cells. Results of this study indicate that anti-T-lymphocyte immunotoxins may form a new class of immunosuppressive agents useful in T-lymphocyte-mediated diseases.

Phase I study of monoclonal antibody-ricin A chain immunotoxin XomaZyme-791 in patients with metastatic colon cancer

Monoclonal antibody 791T/36, recognizing a Mr 72,000 antigen on the surface of colon carcinoma cells, has been used to construct an immunotoxin by conjugating to it the ribosomal inhibitor protein, ricin toxin A chain. The antibody 791T/36 has been shown to bind to membranes of freshly disaggregated tumor cells from human colon tumors, and to localize in tumors in vivo. Subacute toxicology testing in rats receiving immunotoxin i.v. showed, at highest doses, weight loss, decreased serum albumin, and hepatocyte vacuolization without elevation in liver function tests. A Phase I dose escalation study was carried out in which 17 patients with metastatic colorectal cancer were treated with doses of immunotoxin ranging from 0.02 to 0.2 mg/kg/day in 1-h i.v. infusions for a 5-day course. Side-effects included a composite of signs and symptoms thought to be generic to ricin A chain immunotoxins, including decreased serum albumin, mild fever, and flu-like symptoms, all being reversible. Two additional findings, reversible proteinuria and mental status changes, were also noted which may be characteristic of this immunotoxin. By 10-20 days after therapy, most patients developed IgM and IgG antibodies against both the ricin toxin A chain and the immunoglobulin portion of the immunotoxin, which were asymptomatic. A strong anticombining site antibody response was seen. Biological activity manifest as mixed tumor regression was seen in five patients.

Humoral immune responses to XMMCO-791-RTA immunotoxin in colorectal cancer patients

Monoclonal antibody 791 (XMMCO-791) recognizes a colorectal tumour-associated antigen. Antibody 791-ricin A chain immunotoxin (XMMCO-791-RTA) inhibits growth of human tumour xenografts and it is therefore being evaluated for the treatment of colorectal cancer. One of the problems with therapy with mouse monoclonal antibodies is they stimulate humoral responses in patients. However antigens linked to ricin are cytotoxic for B cells and therefore XMMCO-791-RTA may not be immunogenic. The humoral antibody response to murine monoclonal antibody XMMCO-791 (IgG2b) conjugated to the plant toxin, ricin A chain (RTA), was measured in colorectal cancer patients in a phase I clinical trial. All patients produced strong responses to the XMMCO-791 immunoglobulin and to RTA. The predominant response to the antibody was against the idiotypic determinant although anti-subclass and anti-mouse antibodies were also detected. A component of the anti-idiotypic immunoglobulin response in the colorectal cancer patients was directed against the combining site of XMMCO-791. These antibodies inhibited in-vitro binding of XMMCO-791 to target 791 cells and so may be inhibitors of repeated immunotoxin therapy. Immunotoxins do not abrogate the immune response to mouse immunoglobulin in vivo but instead are highly immunogenic.

Potentiation of anti-carcinoembryonic antigen immunotoxin cytotoxicity by monoclonal antibodies reacting with co-expressed carcinoembryonic antigen epitopes

The initial step in ricin A-chain (RTA)-immunotoxin-mediated cell cytotoxicity involves binding to the target cell Ag through the antibody moiety. One of the factors influencing this is the affinity of the antibody component for the target cell Ag. Multiple epitopes on carcinoembryonic Ag have been mapped providing a range of mAb of known specificity. These have been used to show that the cytotoxicity of an immunotoxin containing RTA conjugated to an anti-carcinoembryonic Ag mAb (228-RTA) is potentiated by mAb recognizing different epitopes. The potentiating antibodies also increased the level of target cell binding of antibody 228. Cross-linking of cell bound antibody was not involved because monovalent fragments of a potentiating antibody were effective. The potentiating antibodies modified the binding affinity of 228 antibody increasing the t1/2 of antibody at the tumor cell surface. This increased the dwell time of cell bound antibody and using conjugates of 228 linked to albumin-tetramethylrhodamine it was shown to enhance conjugate endocytosis. These investigations indicate that enhanced antibody affinity leads to increased endocytosis of bound immunoconjugate and potentiates cytotoxicity.

Potentiation of anti-carcinoembryonic antigen immunotoxin cytotoxicity by monoclonal antibodies reacting with co-expressed carcinoembryonic antigen epitopes

The initial step in ricin A-chain (RTA)-immunotoxin-mediated cell cytotoxicity involves binding to the target cell Ag through the antibody moiety. One of the factors influencing this is the affinity of the antibody component for the target cell Ag. Multiple epitopes on carcinoembryonic Ag have been mapped providing a range of mAb of known specificity. These have been used to show that the cytotoxicity of an immunotoxin containing RTA conjugated to an anti-carcinoembryonic Ag mAb (228-RTA) is potentiated by mAb recognizing different epitopes. The potentiating antibodies also increased the level of target cell binding of antibody 228. Cross-linking of cell bound antibody was not involved because monovalent fragments of a potentiating antibody were effective. The potentiating antibodies modified the binding affinity of 228 antibody increasing the t1/2 of antibody at the tumor cell surface. This increased the dwell time of cell bound antibody and using conjugates of 228 linked to albumin-tetramethylrhodamine it was shown to enhance conjugate endocytosis. These investigations indicate that enhanced antibody affinity leads to increased endocytosis of bound immunoconjugate and potentiates cytotoxicity.

Association between clinical symptoms and lymphocyte abnormalities in a population with chronic domestic exposure to industrial solvent-contaminated domestic water supply and a high incidence of leukaemia

An unusually high incidence of leukaemia and recurrent infections was noted in children exposed in utero to domestic water supply contaminated with industrial solvents including trichloroethylene, perchloroethylene and 1,2-transdichloroethylene. Medical and laboratory investigations were carried out on 28 family members of the patients with leukaemia with particular emphasis on the immunological system to determine if they displayed symptoms associated with acute or chronic exposure to these chlorinated hydrocarbons. The principal organ systems affected were neurological, immunological and cardiological. Damage to these systems was found in all subjects by history, physical and laboratory parameters. Damage to the immunological system was manifest by altered ratios of T lymphocyte subpopulations, increased incidence of auto-antibodies, increased infections and recurrent rashes.

Biodistribution of ricin toxin A chain-monoclonal antibody 791T/36 immunotoxin and influence of hepatic blocking agents

Immunotoxin constructed by conjugating ricin A chain to monoclonal antibody 791T/36 has a markedly altered biodistribution when compared to unconjugated antibody. This is principally manifest as hepatic uptake of immunotoxin which appears to be controlled by the ricin A chain (RTA) moiety. This was established by comparing the blood survival and organ distribution of immunotoxin with that of ricin A chain and free antibody using preparations in which either the RTA or antibody, alone or as components of the immunotoxin, was radiolabeled. Gel filtration chromatography of sera from immunotoxin treated animals demonstrated a preferential blood clearance of immunotoxin with high RTA-antibody ratio. Hepatic uptake is dependent upon Kupffer cell recognition of mannose-containing oligosaccharide structures on the RTA moiety of immunotoxin. Mannose-containing blocking agents given with immunotoxin were shown to prolong circulation time of the immunotoxin in blood including those species with higher RTA-monoclonal antibody ratios and reduce liver uptake. Effective blocking agents include ovalbumin, ovomucoid, and mannosyl-lysine (Man3Ly2). These studies demonstrate that agents specifically inhibiting hepatic uptake of immunotoxin significantly alter biodistribution and may improve their therapeutic efficacy.

Inhibition of growth of human tumor xenografts in athymic mice treated with ricin toxin A chain-monoclonal antibody 791T/36 conjugates

Immunotoxin constructed by conjugating ricin A chain to monoclonal antibody 791T/36 specifically inhibits growth of human tumor xenografts which express the gp72 antigen recognized by the antibody component. Dose schedule tests showed that the major response was obtained during the first 5 days of treatment and further prolonged treatment did not improve therapy. Expression of gp72 antigen on tumor cells derived from xenografts in immunotoxin-treated mice was not markedly altered indicating that treatment did not lead to the expansion of tumor antigen deficient tumor cells. The experiments indicate that treatment for short duration with immunotoxin may be the most effective protocol.

Regulation of murine contact sensitivity to urushiol components by serum factors

Mice epicutaneously painted with components of poison ivy urushiol oil exhibit contact sensitivity (as detected by ear swelling reactions) that persist for about 25 days. Sera taken from mice at times when the contact sensitization response is waning suppressed the induction of sensitization to 3-n-pentadecylcatechol (PDC), a urushiol component, in recipients. The suppressive serum factor was present in greatest amount 25 days after sensitization, but was no longer detectable 40 days post sensitization. Suppression was antigen-specific, absorbed out with PDC-immune, but not normal lymph node cells, and transferable with a single 0.6 ml dose 7 days prior to sensitization of recipients. Suppression was transferable by the purified IgG fraction of desensitized mice. Results indicate that contact sensitivity to urushiol in mice is regulated by serum factors.

Mapping of monoclonal antibody-defined epitopes associated with carcinoembryonic antigen, CEA

Six immunoglobulin G monoclonal antibodies reactive with carcinoembryonic antigen (CEA) were evaluated with respect to parameters implicated in their potential diagnostic application and use as tumor targeting agents for cytotoxic drugs or plant or bacterial toxins. Antibody reactivity with surface antigens of the MKN-45 gastric tumor cell line was demonstrated by flow cytofluorimetry. In a subcellular membrane binding assay, each antibody reacted preferentially with membranes isolated from colorectal tumor tissue in comparison with their reaction with membranes from adjacent, apparently normal colonic mucosa. Three of the antibodies (NCRC-23, C228, and 11.285.14) reacted specifically with CEA with little or no reaction with the cross-reacting antigen, NCA. The remaining three antibodies (C24, C161, and C198) were reactive with both CEA and NCA. Analysis of the epitopes defined by these antibodies was performed by competitive binding inhibition assays evaluating the capacity of unlabeled antibodies to compete with 125I-labeled antibodies in their binding to CEA. In addition, double determinant or 'sandwich' radioimmunoassays were employed to examine the coexpression of epitopes on CEA molecules. These studies permitted an epitope map to be constructed which describes the coincidence, overlapping, or independent expression of both CEA specific epitopes and epitopes shared between CEA and NCA. The map may be employed for the selection of antibodies for diagnostic and therapeutic use.

Sensitivity and selectivity of ricin toxin A chain-monoclonal antibody 791T/36 conjugates against human tumor cell lines

Ricin toxin A chain (RTA) was conjugated to monoclonal antibody 791T/36, which was raised originally against human osteogenic sarcoma cell line 791T. The resultant conjugates were characterized and tested for cytotoxicity against a panel of human tumor cell lines representing a defined range of antigenicity with regard to 791T/36. Conjugates were highly cytotoxic for cells expressing high antigen density, inhibiting cell survival at RTA concentrations three to four orders of magnitude lower than that possible with RTA alone. Cytotoxicity of conjugates diminished with decreasing 791T/36 antigen concentration on target cells, but significant effects were seen against cells of low or intermediate antigenicity. Cytotoxicity could be blocked specifically by excess 791T/36 antibody, clearly indicating that antigen binding was a necessary part of the mechanism of action. Comparison with drug-antibody conjugates indicated that RTA immunotoxins are much more active, but discriminate less readily than drug-antibody conjugates between cells of different antigenicity. It is suggested that these properties be taken into account with regard to practical application and future development.

Influence of chemical reactivity of urushiol-type haptens on sensitization and the induction of tolerance

Contact sensitization to components of the urushiol oils of poison oak and poison ivy appears to require covalent bond formation between the o-quinones derived from urushiol catechols and nucleophilic groups on proteins. Previous studies using a murine delayed hypersensitivity model demonstrated that 5-methyl-3-pentadecylcatechol (5-Me-PDC) is an epicutaneous tolerogen to the parent compound and a weak sensitizer to itself. To investigate further the structural requirements for sensitization vs suppression, 5,6-dimethyl-3-pentadecylcatechol (5,6-di-Me-PDC) and 4,5,6-trimethylpentadecylcatechol (4,5,6-tri-Me-PDC) were synthesized. The former compound is blocked at both preferred sites for covalent bond formation and the latter is completely blocked towards conjugate addition reactions. These compounds were tested for sensitizing and suppressive ability. Epicutaneous application of both analogs suppressed subsequent induction of sensitization to 3-pentadecylcatechol (PDC) and 3-heptadecylcatechol (HDC). Lymph node cells from animals treated with 5,6-di-Me-PDC could transfer suppression. The dimethyl analog, 5,6-di-Me-PDC, but not the trimethyl analog also exhibited weak sensitizing capacity. The urushiol analogs 5-pentadecylresorcinol (PDR) and 3-heptadecylveratrole (HDV) which cannot form o-quinones were found to be ineffective sensitizers as well. HDV in addition produced no blastogenesis in draining lymph nodes whereas lymph node cell proliferation induced by 4,5,6-tri-Me-PDC followed the same kinetics as previously observed for HDC. PDR elicited weak proliferation with a different time course. These and previous studies indicate that blocking the C5-position on the catechol ring favors the induction of suppression, although some sensitizing capacity may be retained. Covalent bond formation may not be necessary for the induction of active suppressor cell populations.

Antibodies against osteosarcoma and colon cancer

Two monoclonal antibodies with anti-human tumour reactivity were produced by murine hybridomas. One, 791T/36, is an IgG2b which was raised against a cultured human osteogenic sarcoma cell line, 791T. This antibody reacts with a high proportion of osteogenic sarcomas, and also with other tumour types. It has been used successfully as a tumour localising antibody in vivo and a targeting agent in vitro. The other antibody, C14/1/46, was raised against a human colonic adenoma. An IgM antibody, it reacts with most colorectal carcinoma cells but only with a small subpopulation of cells within the normal mucosa. It has been shown to recognise a difucosylated Type-2 blood-group chain, which has raised expression in colorectal carcinoma tissue.

Induction of suppressor T cells for lymph node cell proliferation after contact sensitization of mice with a poison oak urushiol component

Contact sensitivity with properties of delayed-type hypersensitivity (DTH) can be induced in mice by 3-heptadecylcatechol (HDC, a component of poison oak urushiol oil). Sensitization is effected by painting on abdominal skin and is assessed by measuring ear swelling produced after ear challenge. Further studies on the nature of this sensitization were made by monitoring the induction of lymph node cell (LNC) proliferation (as indicated by increased in vitro uptake of [14C]-thymidine into DNA) after cutaneous treatment with HDC. Draining inguinal LNC proliferation peaked 5-6 days after abdominal application of HDC. LNC taken from sensitized mice at times later than this peak suppressed HDC-induced proliferation when transferred into recipient mice. Such suppressor cells were T lymphocytes as implied by their sensitivity to anti-Thy-1.2 antibody and complement. The suppressive effect appeared to have both specific and non-specific components. LNC containing these T suppressor cells could not suppress the optimal proliferation in vitro of previously sensitized cells, nor was suppressive activity observed against the induction of contact sensitization itself. Thus, although the suppressor cells appeared to act on the afferent phase of sensitization, they may not be directed against the effector cells of DTH.

Induction of antigen specific hyposensitization to poison oak in sensitized adults

Twenty-one adults, highly sensitive to urushiol, the allergen in poison oak/ivy, ingested up to 300 mg of urushiol over three to six months. A control group received placebo capsules. The study was done double blind to evaluate changes in patch test reactivity to urushiol, altered reactivity to an unrelated contract sensitizer, side effects, and duration of hyposensitization. A significant number of subjects in the experimental group (15/21) became hyposensitized. Such hyposensitization was not seen in the control group (2/12), and the difference between groups was significant. No change in reactivity to an unrelated contact sensitizer occurred in subjects hyposensitized to urushiol, suggesting antigen specificity. Retesting up to three months after completion of the protocol indicated that subjects remained hyposensitized without a "rebound" effect during the time. Side effects, detected by questionnaire, were limited to vesicular and urticarial rashes and pruritus ani in 18 of 21 test subjects.

Cellular interactions modulating host resistance to tumours

Active specific immunotherapy of carcinogen-induced rat tumours can be effected using vaccines containing tumour cells admixed with bacterial vaccines such as BCG and C. parvum. The nature of the tumour antigen preparation is important, the most effective immunogen being viable tumour cells whose growth is controlled by responses generated by the bacterial agent in the vaccine. Soluble tumour antigen preparations are usually ineffective due to the preferential induction of suppressor lymphocyte responses in normal hosts. In comparison, removal of suppressor precursors by cyclophosphamide treatment of animals leads to the development of tumour immunity following immunization with soluble antigen preparations. One component of the immune rejection response involves the generation of non-specific effector cells. This type of response can also be induced by administering chemical hypersensitizing agents so as to localize tumour deposits. This approach has proved highly effective in treating the guinea pig line 10 hepatoma by intralesional injection of alkylcatechols. These compounds are highly potent hypersensitizers, being the active constituents of the poison ivy/oak (urushiol oil), and localize in tumour cell membranes.

Induction of persistent tolerance to urushiol in humans

Young nonimmune subjects were injected intramuscularly multiple times with small amounts of urushiol oil derived from poison oak. One week after the last injection this group and another group of age-matched controls were exposed to a sensitizing dose of the oil painted on the skin. All were challenged at 1 mo, then each year for 7 yr. Initially all experimental subjects were tolerant to high challenge doses; this persisted for 1 yr, at which time experimental subjects were no longer completely tolerant but were clinically tolerant (hyporeactive). This state persisted for at least 4 yr, and this represents complete tolerance followed by long-lasting hyposensitization.

Antitumour reactions of monoclonal antibody against a human osteogenic-sarcoma cell line

Monoclonal antibody against an osteogenic-sarcoma cell line (791T) was prepared by production and cloning of a somatic-cell hybrid between the mouse myeloma P3-NS1 and spleen cells from 791T-immunized mice. Three clones of hybridoma producing antibody against 791T, as detected by 125I-labelled Protein A binding, were tested against a range of normal and tumour cell targets to determine the pattern of expression of the antigen detected. The 3 clones had identical activity. They reacted strongly against 791T cells and another osteogenic sarcoma, 788T, and more weakly against a further 2 from a total panel of 10 osteogenic-sarcoma lines. The antibody was negative for fibroblasts from the donor of 791T, and for other fibroblasts, human red blood cells, human peripheral mononuclear cells and sheep red blood cells. When tested against a panel of unrelated tumours, they reacted against individual cell lines derived from carcinomas of colon, lung, bladder and cervix. These cross-reactions were not observed with other colon or lung carcinomas, and it is suggested that the antibody was reacting with a tumour-associated antigen expressed randomly on different tumour types, rather than specifically on osteogenic sarcomas.

Regiospecific attack of nitrogen and sulfur nucleophiles on quinones derived from poison oak/ivy catechols (urushiols) and analogues as models for urushiol-protein conjugate formation

Attempts to characterize potential biologically important covalent interactions between electrophilic quinones derived from catechols present in poison oak/ivy (urushiol) and biomacromolecules have led to the analysis of model reactions involving sulfur and amino nucleophiles with 3-heptadecylbenzoquinone. Characterization of the reaction products indicates that this quinone undergoes regiospecific attack by (S)-N-acetylcysteine at C-6 and by 1-aminopentane at C-5. The red solid obtained with 1-aminopentane proved to be 3-heptadecyl-5-(pentylamino)-1,2-benzoquinone. Analogous aminobenzoquinones were obtained with the quinones derived from the 4- and 6-methyl analogues of 3-pentadecylcatechol. All three adducts absorbed visible light at different wavelengths. When the starting catechols were incubated with human serum albumin almost identical chromophores were formed. These results establish that cathechols responsible for the production of the poison oak/ivy contact dermatitis in humans undergo a sequence of reactions in the presence of human serum albumin that lead to covalent attachment of the catechols to the protein via carbon-nitrogen bonds. Estimations of the extent of this binding indicate that, at least with human serum albumin, the reaction is quantitative.

Circulating immune complexes in patients with bone tumours

Sera from 62 patients with osteogenic sarcoma and 12 with malignant giant-cell tumour were tested for the presence of immune complexes by the 125I-Clq binding assay. Elevated serum Clq binding activity was found in 67.7% of the osteogenic sarcoma patients and in 75% of the giant-cell tumour patients. These results were compared with those obtained with five sera from patients with benign bone tumours and 20 sera from normal young donors. In the last two groups, the incidence of elevated Clq-binding activity was 0% and 5%, respectively. In some patients with giant-cell tumours, pre- and post-operative serum samples were studied, showing a decrease in test values after tumour resection. Preliminary sequential studies of individual patients indicate that the 125I-Clq binding assay may be useful for monitoring patients with bone tumours.

In vitro studies of poison oak immunity. II. Effect of urushiol analogues on the human in vitro response

Studies were performed to ascertain the effect of urushiol analogues on the in vitro lymphocyte blastogenesis elicited by urushiol in peripheral blood lymphocytes taken from individuals sensitized to poison oak or ivy. Urushiol is a mixture of alkylcatechols composed of a catechol ring coupled to mono-, di-, or tri-unsaturated C-15 or C-17 carbon side chains. Each of these two moieties, catechol ring and side chain, was tested for its role in eliciting reactivity. Analogues tested represented the catechol ring (3-methylcatechol), the mono- or di-unsaturated side chain (oleic or linoleic acid), and the saturated side chain coupled to a catechol ring (pentadecylcatechol), a blocked catechol ring (heptadecylveratrole), or a resorcinol (pentadecylresorcinol). Urushiol with a blocked catechol ring (urushiol dimethyl ether) was also included. Of these, only pentadecylcatechol evoked reactivity in sensitized lymphocytes, and this reactivity was only a fraction of that evoked by urushiol. This suggested that the system has some requirement for the side chain, and that the catechol ring is critical for reactivity. This was further investigated by testing the ability of some of these analogues to inhibit urushiol-specific blastogenesis. No inhibition was noted with compounds bearing the saturated side chain with modified ring structures (pentadecylresorcinol and heptadecylveratrole). However, both 3-methylcatechol and pentadecylcatechol (at equimolar concentrations) blocked reactivity. The results of our experiments suggested that although both the side chain and the catechol ring are required for reactivity, the latter is most critical. Unsaturation in the side chain is important for maximal reactivity because the saturated catechols were only partially as active as the urushiol oil. There may be a greater dose requirement for the catechol ring than for the side chain.

In vitro studies of poison oak immunity. I. In vitro reaction of human lymphocytes to urushiol

Poison oak, ivy, and sumac dermatitis is a T-cell-mediated reaction against urushiol, the oil found in the leaf of the plants. This hapten is extremely lipophilic and concentrates in cell membranes. A blastogenesis assay employing peripheral blood lymphocytes obtained from humans sensitized to urushiol is described. The reactivity appears 1--3 wk after exposure and persists from 6 wk to 2 mon. The dose-response range is narrow, with inhibition occurring at higher antigen concentrations. Urushiol introduced into the in vitro culture on autologous lymphocytes, erythrocytes and heterologous erythrocytes produces equal results as measured by the optimal urushiol dose, the intensity of reaction, and the frequency of positive reactors. This suggests that the urushiol is passed from introducer to some other presenter cell. Although the blastogenically reactive cell is a T cell, there is also a requirement for an accessory cell, found in the non-T-cell population, for reactivity. Evidence is presented that this cell is a macrophage.

Transfer of contact sensitivity to beryllium using dialyzable leukocyte extracts (transfer factor)

Transfer factor derived from lymphocytes of donors with strong cellular immunity against beryllium was intradermally or subcutaneously injected into unprimed or subclinically primed human recipients who were patch test-negative. These recipients were challenged with beryllium at weekly intervals thereafter. Subjects who had been subclinically primed and received transfer factor either intradermally or subcutaneously showed transient patch test reactivity to the challenge. Subjects who received transfer factor but were not primed and subjects who had been primed but did not receive transfer factor showed no such conversion. This is the first demonstration of transfer of contact sensitivity in man using transfer factor, and it suggests that subclinical priming is necessary for such transfers.

Antigenic differences among osteogenic sarcoma tumor cells taken from different locations in human tumors

Sections were taken from the center, midzone, and margin of four human osteogenic sarcomas and one fibrosarcoma. Single-cell suspensions of tumors were examined in an indirect immunofluorescence assay with autologous or homologous anti-osteogenic sarcoma antisera as the intermediate reactant and fluorescein-labeled anti-human IgG as the final reactant. Cells were stained under conditions in which the fluorescence intensity was directly proportional to the density of the tumor-associated antigen on these cells. The density of tumor-associated antigen on cells from the center of the five tumor masses was low; cells from the midzone had intermediate levels of tumor antigen density, and cells at the margin had the highest levels. Similar preparations stained with polyspecific anti-HLA antisera did not demonstrate such a gradient. Since osteogenic sarcomas grow outward from the center, with the outer margin populated by the youngest cells, these results suggest that the oldest cells in the tumor bear the least tumor antigen, and the youngest tumor cells have the most. This is not compatible with theories which postulate that the immune system modulates the growth of a tumor so that only the least antigenic cells are allowed to grow. Alternative mechanisms are discussed.

Circadian rhythm of stimulated lymphocyte blastogenesis. A 24 hour cycle in the mixed leukocyte culture reaction and with SKSD stimulation

The in vitro measurement of stimulated T lymphocyte blastogenesis by the incorporation of 14C-thymidine can be shown to be an acceptable and precise measurement with highly significant variations in blastogenesis over a 24 hr period. This circadian rhythm for human T lymphocyte blastogenesis has been demonstrated with specific antigen (SKSD) and in mixed leukocyte culture (MLC). The hours of peak reactivity were different for the SKSD stimulation and the MLC reaction. This biologic cycle in T cell reactivity has significant implications for the immunologic response.

Copper and zinc levels in serum from human patients with sarcomas

Serum copper levels (SCL) and serum zinc levels (SZL) were evaluated in 19 patients with sarcomas, 12 of which were osteosarcomas at various stages. Patients with primary or metastatic osteosarcoma had elevated SCL, whereas amputated osteosarcoma patients who were clinically tumor-free had nearly normal SCL. Patients with primary osteosarcoma had elevated SZL, those with metastases had depressed zinc levels, and amputated patients who were clinically tumor-free and nearly normal SZL. Thus, the ratio of SCL:SZL in metastatic osteosarcoma patients is higher than in patients with primary osteosarcoma. SCL and SZL are compared to clinical histories for selected patients. Patients with the more advanced disease and poorest prognoses had the most elevated SCL and highest SCL:SZL ratios. It appears that the determination of SCL and SZL in osteosarcoma patients may be of value in prognosis and therapy evaluation; furthermore, the ratio of SCL:SZL may be useful in discriminating between patients with primary and metastatic osteosarcoma.