Cutaneous Delayed Hypersensitivity Response Research Articles

Cancer immunotherapy by fusions of dendritic and tumour cells and rh‐IL‐12

Vaccination with fusion cells (FCs) comprising dendritic cells and tumour cells as well as administration of interleukin-12 (IL-12) showed a significant therapeutic effect against established tumours in mouse experimental models. We conducted immunotherapy against various malignant tumours using the FCs and rhIL-12, and investigated the safety and efficacy of the therapy. Patients' DCs were mixed with autologous irradiated tumour cells and treated with 50% polyethylene glycol to generate FCs. The FCs were inoculated intradermally, and then 30 ng kg(-1) of rhIL-12 was injected at the same sites 2 and 6 days later. This process was carried out as one cycle, and three of these cycles were repeated at 1-week intervals to comprise one course. After completing the course, its safety and therapeutic effects were estimated. The most frequently observed adverse event was fever, observed in 26% of patients in the first cycle. Decrease in white blood cell and an increase in serum ALT were observed in 28% and 25%, respectively. Three out of 12 patients with a malignant brain tumour (25%) achieved a partial response (PR), but other patients with a malignant tumour showed no regression of their tumours. Thirteen out of 16 patients with a brain tumour (81%) showed cutaneous delayed hypersensitivity responses. However, only one of 16 patients (6%) with a malignant tumour other than a brain tumour developed such responses. Immunotherapy using a FC vaccine and rhIL-12 induced no serious adverse reactions, and provided good therapeutic responses in some of the patients with a brain tumour.

Peripheral anergy and local immune hyperactivation in sarcoidosis: a paradox or birds of a feather

Sarcoidosis is a multisystem non-caseating granulomatous disorder, which is frequently self-limiting. Not only does its aetiology remain an enigma, but equally curious is its immunological background, which appears to be pathognomonic for this disease. Studies have shown aberrant cell-mediated active, if not overactive, immune responses at sites of inflammation [1] in the presence of hypergammaglobulinaemia [2] and cutaneous anergy to particular antigens, including tuberculoprotein but not Kveim antigen [3]. This apparent paradox in peripheral and local cellular immune responses, with preferential activation at the organ level, has provoked a great deal of interest over the years, and begged the question of whether the proposed depression in peripheral cellmediated immunity in sarcoidosis is in fact real or apparent. The accumulation of activated oligoclonal CD4 T lymphocytes [4] and specific subpopulations of macrophages [5,6], together with a release of various proinflammatory cytokines [7], determine the immune phenomena as well as the development and fate of granulomata at the sites of sarcoid inflammation. The recruitment of CD4 T lymphocytes around granulomata is more prominent within fresh active lesions, and tends to diminish as the granulomata mature [8]. Indeed, as lesions become less active, these cell types decrease, and T cells expressing CD8 surface antigens predominate [8]. A similar switch in immunoregulatory T cells has also been observed in animal models of granulomatous lung disease [9,10]. In patients with active sarcoidosis, the increase in activated T cell numbers at sites of granulomatous inflammation is simultaneously accompanied by an absolute decrease in the number of circulating T cells in autologous peripheral blood. One of the earliest immunological abnormalities to be observed in active sarcoidosis is a partial to complete anergy to tuberculin purified protein derivative (PPD). Such skin anergy also extends to certain antigens, e.g. Trichophyton, mumps virus, streptokinase/ streptodornase, Candida, as well as dinitrochlorobenzene. The incidence of anergy to tuberculoprotein and other antigens in sarcoid patients varies from 30% to 70%, depending on the number of antigens used [3,11,12]. This anergy appears to parallel disease severity, being especially marked when the sarcoidosis is clinically active, and disappearing months to years after resolution of the disease. Usually such cutaneous anergy is associated with depressed cellular immunity. The partial cutaneous anergy observed in sarcoidosis is frequently attributed to a reduction in the number and function of circulating T lymphocytes [13]. It has been suggested that the reduction of delayed-type skin test reactivity could reflect a depletion of the population of immunoreactive cells being sampled from the skin. It is recognized that in granulomatous disease there is an altered circulating pattern for T lymphocytes with the onset of inflammation. In particular, CD4 T cells become sequestrated in central lymphoid organs and sites of inflammation, leaving proportionately increased numbers of CD8 T cells in the peripheral blood [14]. In sarcoid patients, the ratio of CD4 to CD8 T cells in the blood may be normal or slightly decreased, with corresponding T cell ratio in the lung being 4–10 times greater than normal [15]. At the height of inflammation, the compartmentalized CD4 T cells have been shown to express IL-2R, very late activation Ag1, and DR class II MHC molecules: the hallmarks of antigenstimulated T cells [16,17]. In addition, it appears that these CD4 T lymphocytes are oligoclonal, consistent with a conventional antigen-driven process [18,19] (albeit the nature of the antigenic stimulus in sarcoidosis remains unclear). However, whilst T cells obtained from inflamed sites appear to be activated both morphologically and functionally, with augmented responses to external stimuli such as lectins and antigens, the functional response of autologous peripheral blood lymphocytes to mitogen and recall antigen is impaired, with consequent depression of B cell function in vitro. In addition, inhibitory factors, partly derived from monocytes, have been isolated from the blood of active sarcoid patients, and shown to inhibit the in vitro response of normal lymphocytes to mitogens and antigens [13,20,21]. Such findings in the peripheral blood have been related to the observed depression in certain cutaneous delayed hypersensitivity responses [13,22]. Despite this apparent cutaneous anergy, patients with sarcoidosis are uniquely capable of mounting a positive cutaneous reaction to a Kveim antigen. The mechanisms of this Kveim response are not entirely clear. Although Kveim test lesions exhibit histopathologic similarities to sarcoid granulomata, there are marked differences between the Kveim reaction and the classic DTH skin response. The most obvious difference is in the kinetics of the two reactions. DTH reaction begins at 8 h, peaks at 24–48 h, and resolves by 96–120 h. By contrast, the Kveim reaction takes 4–6 weeks to develop. Furthermore, no specific antigen in the Kveim preparation has been identified as the inducing agent in this response, and no convincing data have been generated to show reproducibly that sarcoid lymphocytes are actively sensitized to the Clin Exp Immunol 1997; 110:1–3

A comparison of the capacity of six cold-pressed plant oils to support development of acquired immune competence in the weanling mouse: superiority of low-linoleic-acid oils

The objective of this investigation was to compare, at several levels of intake, the capacity of diverse cold-pressed plant oils to support development of acquired immune competence assessedin vivoin the weanling mouse. Safflower, maize, soyabean, rapeseed, flaxseed and olive oils were selected to represent widely differing 18: 1n-9, 18: 2n-6 and 18: 3n-3 contents, and each oil was fed at three dietary levels (40, 80 and 160 g/kg) as the exclusive source of fat. C57BL/6J mice, ten males and ten females, had free access to each diet for 28 d beginning at 19 d of age. The primary serum haemagglutinin response to sheep red blood cells and the primary cutaneous delayed hypersensitivity response to dinitrochlorobenzene were used to assess humoral and cell-mediated competence respectively, on day 28. A zero-time control group, assessed immunologically at 19 d of age, was also included (n32). Independently of dietary oil level, flaxseed, rapeseed, olive and soyabean oils supported development of a more vigorous antibody response than safflower (a useful point of reference, being rich in 18: 2n-6 but low in 18: 1n-9 and 18: 3n-3), whereas only flaxseed oil supported development of cell-mediated responsiveness exceeding that of safflower-fed mice. Independently of oil type, development of both immunological indices correlated negatively with intake of 18: 2n-6, and development of humoral competence varied inversely with dietary oil level. A low content of 18: 2n-6, perhaps less than 20 g/100 g fatty acids, appears important to the capacity of a plant oil to support development of acquired immune competence in the young.

The role of zinc and vitamin A in persistent diarrhea among infants and young children.

The role of zinc and vitamin A in persistent diarrhea among infants and young children.

Nutritional support and prognosis in patients with head and neck cancer.

We retrospectively studied the relationship between nutritional status as indicated by the presence or absence of the cutaneous delayed hypersensitivity response and treatment-related morbidity, disease recurrence, and survival at 2 years in 67 consecutive patients with head and neck carcinoma. Serial nutritional assessments were conducted throughout the course of combined initial antineoplastic treatment and nutritional support. The presence of cell-mediated immunity at the end of treatment was associated with a 2-year survival rate of 100%, whereas patients who were anergic at the end of treatment had a 2-year survival rate of 48% (P < 0.01). Morbidity due to surgical therapy and tumor recurrence rates were also higher in the anergic group (P < 0.01). Prognosis in head and neck cancer is based on many factors, but vigorous nutritional support during initial treatment may have some effect on morbidity, tumor recurrence, and survival time.

Autologous melanoma vaccine induces inflammatory responses in melanoma metastases: relevance to immunologic regression and immunotherapy.

Human primary malignant melanoma is often accompanied by a host response of infiltrating lymphocytes suggestive of tumor antigen-induced immunity and correlated in some tumors with prognosis. Whereas metastatic melanoma deposits typically are not inflamed and contain relatively few lymphocytes and dendritic immune cells, immunization with autologous melanoma-cell vaccine may induce a clinical inflammatory response associated with mononuclear-cell infiltration. In this study, we characterize immune responses to dermal and subcutaneous melanoma metastases in dinitrophenyl (DNP)-pre-sensitized patients immunized with DNP-conjugated melanoma cells. Patients so treated develop cutaneous delayed hypersensitivity responses to DNP-conjugated autologous mononuclear cells, and approximately one-half show clinical evidence of inflammation and regression of metastases within 2-4 months. Whereas pre-vaccination biopsies of metastatic melanoma failed to reveal significant infiltration by lymphocytes, biopsies obtained after vaccination and coincident with clinical inflammation were markedly infiltrated preponderantly by T cells with a CD8+ phenotype. Clustering of these cells about individual degenerating melanoma cells in a manner analogous to "satellitosis" was a consistent feature of this reaction. Enhanced expression of intercellular adhesion molecule-1 (ICAM-1) and human leukocyte antigen (HLA)-DR by melanoma cells were invariably associated with zones of T-cell infiltration, whereas diminished or absent expression was observed in relatively unaffected regions of tumors. Numerous HLA-DR+, CD4+, CD1-, Leu-1- dendritic cells were also associated with zones of early T-cell infiltration. These data indicate that clinical inflammation and regression of metastatic melanoma induced by autologous melanoma-cell vaccine involves activated T cells with cytotoxic-suppressor phenotype and dendritic cells putatively capable of local antigen presentation. ICAM-1 upregulation on melanoma cells is a likely mediator of ligand interaction between infiltrating T cells and target cells in this model of antigen-induced host anti-tumor response. Structural alterations identified in this setting (e.g., tumor cell satellitosis) may provide additional insight into identifying features of naturally occurring host immune responses to primary cutaneous melanomas.

Autologous Melanoma Vaccine Induces Inflammatory Responses in Melanoma Metastases: Relevance to Immunologic Regression and Immunotherapy

Human primary malignant melanoma is often accompanied by a host response of infiltrating lymphocytes suggestive of tumor antigen-induced immunity and correlated in some tumors with prognosis. Whereas metastatic melanoma deposits typically are not inflamed and contain relatively few lymphocytes and dendritic immune cells, immunization with autologous melanoma-cell vaccine may induce a clinical inflammatory response associated with mononuclear-cell infiltration. In this study, we characterize immune responses to dermal and subcutaneous melanoma metastases in dinitrophenyl (DNP)-pre-sensitized patients immunized with DNP-conjugated melanoma cells. Patients so treated develop cutaneous delayed hypersensitivity responses to DNP-conjugated autologous mononuclear cells, and approximately one-half show clinical evidence of inflammation and regression of metastases within 2-4 months. Whereas pre-vaccination biopsies of metastatic melanoma failed to reveal significant infiltration by lymphocytes, biopsies obtained after vaccination and coincident with clinical inflammation were markedly infiltrated preponderantly by T cells with a CD8+ phenotype. Clustering of these cells about individual degenerating melanoma cells in a manner analogous to "satellitosis" was a consistent feature of this reaction. Enhanced expression of intercellular adhesion molecule-1 (ICAM-1) and human leukocyte antigen (HLA)-DR by melanoma cells were invariably associated with zones of T-cell infiltration, whereas diminished or absent expression was observed in relatively unaffected regions of tumors. Numerous HLA-DR+, CD4+, CD1-, Leu-1- dendritic cells were also associated with zones of early T-cell infiltration. These data indicate that clinical inflammation and regression of metastatic melanoma induced by autologous melanoma-cell vaccine involves activated T cells with cytotoxic-suppressor phenotype and dendritic cells putatively capable of local antigen presentation. ICAM-1 upregulation on melanoma cells is a likely mediator of ligand interaction between infiltrating T cells and target cells in this model of antigen-induced host anti-tumor response. Structural alterations identified in this setting (e.g., tumor cell satellitosis) may provide additional insight into identifying features of naturally occurring host immune responses to primary cutaneous melanomas.

Studies of transformer repair workers exposed to PCBs: I. Study design, PCB concentrations, questionnaire, and clinical examination results.

A cross-sectional study compared 55 transformer repairmen, 38 currently, and 17 previously exposed to polychlorinated biphenyls (PCBs) with 56 non-exposed subjects. PCBs exposures occurred from air and contaminated surfaces, predominantly from Aroclor 1260 with some exposure to Aroclor 1242. Each worker underwent: a questionnaire; standardized medical examination; delayed hypersensitivity testing; and determination of serum and adipose tissue lipid total PCB concentrations. Adipose and serum [PCBs] were significantly higher in the currently exposed, but previously exposed workers did not differ significantly from comparison subjects. No subjects had a classical syndrome of PCB poisoning. A number of neurobehavioral and irritant symptoms were significantly more prevalent in the exposed group, but were probably not related to PCBs. Comedones were more frequent in the exposed group, but no evidence of classical chloracne was noted. Cutaneous delayed hypersensitivity responses to mumps and to trichophyton antigens did not differ between the groups. The association of PCBs with job functions were explored.

Topical zinc sulfate augmentation of human delayed type skin test response

The ability of topical zinc sulfate to augment the cutaneous delayed hypersensitivity response to Candida antigen was evaluated in 47 adults (15 controls and 32 hospitalized patients). On each adult subject, intradermal standard Candida extract was administered to each forearm followed immediately by topical application of 10% zinc sulfate in Aquaphor ointment on one arm and Aquaphor alone on the other arm. The reaction size was assessed in a single blinded manner. Of the 24 subjects who reacted positively to Candida antigen, a significantly larger (p less than 0.01) number of individuals showed an augmented cutaneous delayed hypersensitivity response in the arm on which the topical zinc sulfate had been applied. However, when patients were stratified by plasma zinc concentrations, only the normal plasma zinc patient group demonstrated a statistical augmentation. Possible mechanisms and selectivity of this observed effect are discussed. These findings suggest a role for topical zinc application to augment cutaneous immune responsiveness.

Genetic differences in methylcholanthrene-mediated suppression of cutaneous delayed hypersensitivity in mice

The suppression of the cutaneous delayed hypersensitivity response to 2,4-dinitrofluorobenzene (DNFB) by 3-methylcholanthrene (MC) was investigated in C57BL/6J (B6) and DBA/2J (D2) mice and their hybrid, backcross, and intercross progeny. MC administration resulted in a dose-dependent suppression of ear swelling in B6 mice but was without effect in D2 mice. This dose-dependent suppression of cutaneous delayed hypersensitivity parallelled the dose-dependent induction of hepatic aryl hydrocarbon hydroxylase activity in B6 mice. At 80 mg/kg MC, a dose which was maximally immunosuppressive in B6 mice, no effect on hematocrit, white blood cell count, or spleen-to-body weight ratio occurred in either B6 or D2 mice. Under these same conditions, however, a pronounced decrease in thymus-to-body weight ratio was consistently observed in B6 mice. When experiments were performed using B6D2F 1 mice, the effect of MC (80 mg/kg) was indistinguishable from that obtained with the B6 parental strain. (B6D2) × D2 backcross and (B6D2) × (B6D2) intercross progeny were tested also for the effect of MC on their cutaneous delayed hypersensitivity response to DNFB. Using a cutoff point calculated by a computerized iterative maximum likelihood procedure, immunosuppressed offspring were distinguished from those unaffected. The observed number of immunosuppressed mice in both the backcross (49%) and F 2 (68%) generations were consistent with those which would be expected if the susceptibility to MC-mediated immunosuppression were inherited as an autosomal dominant trait. Moreover when the backcross and intercross progeny were phenotyped for aromatic hydrocarbon responsiveness prior to the determination of their cutaneous delayed hypersensitivity response, MC-mediated immunosuppression was found to cosegregate with the Ah b allele.

Effects of exposure to ozone on susceptibility to experimental tuberculosis

Exposure of mice to 1.96 mg m 3 ozone (O 3) 3 h day , 5 days/week, for up to 8 weeks beginning at 1 or 2 weeks after challenge with Mycobacterium tuberculosis R 1Rv resulted in significant enhancement of bacterial titers in the lungs at 5 through 8 weeks after challenge when compared to mice exposed to filtered air. Exposure to lower concentrations of O 3 did not produce any significant changes compared to controls. Exposure of guinea pigs to 2.9 mg m 3 O 3 for 3 h immediately after challenge with M. tuberculosis resulted in a suppression of the cutaneous delayed hypersensitivity response, without affecting the serum hemagglutination antibody titers. However, exposure of guinea pigs to 0.98 mg m 3 O 3 3 h day for 5 days, initiated within 3 h after the infectious challenge, enhanced hemagglutination antibody titers initially, but the delayed hypersensitivity reaction did not differ from controls.

The effects of dialyzable products from human leukocyte extracts on cutaneous delayed-hypersensitivity response.

Fractions from human whole leukocyte lysates were prepared by sequential double dialysis against membranes with cut-offs of m.w. 12,000 and 3500, and by elution chromatography on Sephadex G-10. The effect of localized intracutaneous implantation of fractions with m.w. less than 3500 was studied. Two types of response were obtained: 1) the amplification of response to antigen to which the donor had preexisting immunity, and 2) the induction of inflammatory response histologically resembling delayed hypersensitivity in the absence of added antigen. The substances mediating these responses could be separated into unique components by use of a long (1 x 150 cm) G-10 column, or by hydroxylapatite chromatography. The active principles were derived from leukocyte extracts (as demonstrated by their absence from autologous RBC extracts prepared by identical methodology), and the histopathologic appearances after intracutaneous implantation were compatible with those of a delayed-hypersensitivity response. No evidence of transfer of antigen-specific information from a sensitive donor to a nonsensitive recipient was obtained under the conditions of study.

The Immune System in 40 Aplastic Anemia Patients Receiving Conventional Therapy

Forty patients with aplastic anemia who were being considered for bone marrow transplantation were studied by in vivo and in vitro techniques to determine if the immune system in aplastic anemia is generally affected. It was found that patients with aplastic anemia had mild lymphopenia, with levels of circulating thymus-derived and bone-marrow-derived cells that were apparently secondarily depressed. Marked monocytopenia was observed, but this finding was mitigated by recovery of essentially normal numbers of mononuclear phagocytic cells (using a discontinuous Hypaque-Ficoll density gradient) and by the ability of patient mononuclear cells to participate at least as well as control cells in proliferative responses in vitro. More patients had abnormally low levels of the immunoglobulin classes than would be predicted from the laboratory normal range; however, no consistent pattern of immunoglobulin deficiency was found. Levels of complement components, antiviral antibody, and isohemagglutinins were essentially normal. However, cutaneous delayed hypersensitivity responses were impaired. Proliferative responses in vitro to mitogens and antigens (except staphylococcal filtrate) were at least as vigorous as the responses of controls. Patient mononuclear cells stimulated allogeneic cells as well as did MHC-identical sibling cells, and they responded at least as well to allogeneic unrelated cells. Clinically the patients did not suffer from fungal or protozoal infections, which are common in immune deficiency syndromes. Thus these aplastic anemia patients were little different from normal subjects. The mild lymphopenia, impaired delayed hypersensitivity, and modestly depressed IgG and IgM levels were correlated with corticosteroid therapy.

Investigation of a cutaneous delayed hypersensitivity response as a means of detecting Salmonella dublin infection in cattle

Delayed hypersensitivity reactions developed 48 to 96 h after intradermal injection of killed Salmonella dublin in 25 of 28 cattle which had been inoculated intravenously, and in five of 10 cattle which had been inoculated orally with S dublin 24 to 493 days previously. Control animals showed no delayed hypersensitivity reactions. Persistence of infection in five of the intravenously inoculated and in four of the orally inoculated animals was confirmed by isolation of S dublin from the carcases at necropsy one week after skin testing. Failure to isolate the organism from the carcases of 21 animals which had reacted positively to the intradermal test did not eliminate the possibility of their being carriers of S dublin. Skin testing was concluded to be a reliable means of identifying animals which had been, and possibly still were, infected systemically with S dublin. However recovered animals might be falsely identified as infected. Repeated testing gave misleading results.

Relationship between cutaneous delayed hypersensitivity and cell-mediated immunity in vitro responses assessed by diphtheria and tetanus toxoids

Cutaneous delayed hypersensitivity (CDH) testing with microbial antigens in man is thought to reflect the status of cell-mediated immunity (CMI). We have evaluated diphtheria-tetanus (DT) and tetanus (T) toxoids by comparing the CDH response with in vitro parameters of CMI: lymphocyte deoxyribonucleic acid (DNA) synthesis, leukocyte inhibition factor (LIF) in 5 immunized adults, and lymphotoxin release in 2 adults. Cord blood lymphocytes were used as controls for each assay. A dose response with both toxoids was used to compare the CDH reaction with each in vitro assay, establishing the maximum response and threshold dose which gave a positive response. All subjects had a positive CDH response to both antigens (≥5 mm induration at 48 hr), positive DNA synthesis (stimulation index ≥3), LIF release (migration ≤80%), and lymphotoxin production, while cord blood lymphocytes were usually negative to all in vitro assays. No consistent quantitative relationships between CDH reactions and in vitro CMI responses were seen. Threshold antigen dose data revealed that DNA synthesis was approximately ten times as sensitive an assay as CDH, and 10 5 times as sensitive as the LIF technique. No difference in sensitivity was noted between DT and T toxoids. Three subjects re-evaluated 16 mo after the initial study showed positive CDH and CMI responses to tetanus toxoid, although the antigen dosage required varied considerably. We conclude that the CDH response with either toxoid in the concentrations used is a good indicator of CMI in the immunized individual. Although recommended starting antigen dose is given for each assay, a dose response for each assay must be performed to adequately evaluate the CMI responsiveness to a test antigen.

Sequential evaluation of cutaneous delayed hypersensitivity responses to recall and to lymphoid cell line antigens in Burkitt's lymphoma.

Delayed cutaneous hypersensitivity reactions to standard recall antigens (candidin, mumps and PPD), to crude membrane extracts of a cell line derived from Burkitt's lymphoma (Raji) and to cell line derived from normal lymphocytes (F265) were sequentially evaluated in 44 patients with Burkitt's lymphoma. Sixteen patients (36%) manifested delayed hypersensitivity responses to the standard antigens and seven (16%) to the Raji membrane extract at presentation. Following successful chemotherapy, there was prompt and significant improvement of reactivity to both the standard and Raji antigens (p greater than 0.001), suggesting that the initial impairment of delayed hypersensitivity was most likely related to tumor burden. By 9 months after treatment, all patients in sustained remission expressed reactivity to Raji and 21 of 22 to the standard antigens. None of the patients skin-tested with the F265 extract at presentation gave a positive response and only one subsequently expressed reactivity after remission was induced. On relapse, reactivity to the standard antigens was more readily lost (4 of 11) then reactivity to the Raji extract (1 of 7). Pretreatment delayed hypersensitivity to the standard antigens also correlated better with long-term survival than to pretreatment responses to Raji. It remains to be determined whether the antigens expressed in the Raji extract are indeed tumor-specific or related to Epstein-Barr virus.

THE USE OF DIPHTHERIA AND TETANUS TOXOIDS TO ASSESS CELL-MEDIATED IMMUNITY (CMI)

In a previous study, we demonstrated that diphtheria-tetanus (DT) toxoids produce positive cutaneous delayed hypersensitivity (CDH) in the immunized child regardless of age. In this study, we compare the CDH response to DT and T toxoids with in vitro parameters of CMI: lymphocyte DNA synthesis and leukocyte inhibition factor (LIF) In five immunized adults. Cord blood lymphocytes were used as controls for each assay. A dose response with both toxoids compared the CDH reaction with each in vitro assay, establishing the maximum response and threshold dose which gave a positive response. All subjects had a positive CDH response to both antigens (≤5nm induration at 48 hours), positive DNA synthesis (stimulation index above 3) and LIF release (migration ≤ 80%), while cord blood lymphocytes were usually negative to all in vitro assays. The subjects with the largest CDH reactions generally had the greatest lymphocyte DNA synthesis and lowest threshold doses. DNA synthesis was approximately ten times as sensitive an assay as CDH and 105 times as sensitive as the LIF technique. No difference in sensitivity was noted between DT and T toxoids. We conclude that the CDH response with either toxoid in the concentrations used is a good indicator of CMI in the immunized individual. These toxoids are particularly valuable for evaluating CMI in the young child.

Selective T cell killing of human lymphocytes by ultraviolet radiation

The effects of ultraviolet radiation (uv) on human B and T lymphocytes were studied. In vitro studies showed that T lymphocytes were more sensitive to uv than B lymphocytes as assessed by eosin-dye exclusion. Following uv exposure, the viable lymphocytes responded to mitogens (PHA, PWM), and functional B lymphocytes were present at a time when no viable T cells were detected. Varying doses of uv were required to abrogate different in vitro responses (proliferative response to antigen or allogeneic cells, MIF production, and cell-mediated lympholysis). In vivo, uv was able to diminish an established cutaneous delayed hypersensitivity response. In vitro uv treatment of parental mouse spleen cells eliminated a graft-versus-host reaction in F 1 recipients as determined by the spleen index. The basis for the differential effect of uv on B and T lymphocyte viability and functional responses is unknown.

Cutaneous delayed hypersensitivity reactions to soluble melanoma antigen in patients with ocular malignant melanoma.

We studied the cutaneous delayed hypersensitivity responses to a soluble melanoma antigen in 32 patients with the initial clinical diagnosis of ocular melanoma and in seven control patients. Eighteen out of 19 patients who had pathologically confirmed ocular melanomas were positive to this antigen, as were eight other patients clinically thought to have choroidal melanomas. All seven controls were negative on skin testing with this antigen, as were five patients who were initially thought to have ocular melanomas but who, on extensive work-up, were considered to have other, nonmelanoma, ocular lesions. Thus, patients with ocular malignant melanomas have cell-mediated immunity against an antigen common to systemic malignant melanoma. This delayed hypersensitivity assay may assist in the diagnosis of ocular melanoma, especially in patients with opaque media or those in whom ocular melanoma must be distinguished from metastatic lesions to the choroid. (N Engl J Med 291:274–277, 1974)

Cutaneous Delayed Hypersensitivity Responses of Patients with Retinoblastoma to Standard Recall Antigens and Crude Membrane Extracts of Retinoblastoma Tissue Culture Cells

Cutaneous Delayed Hypersensitivity Responses of Patients with Retinoblastoma to Standard Recall Antigens and Crude Membrane Extracts of Retinoblastoma Tissue Culture Cells