Indicator Of Cell-mediated Immunity Research Articles

Moringa (Moringa oleifera Lam.) Pod Meal: Nutrient Analysis and its Effect on the Growth Performance and Cell-Mediated Immunity of Broiler Chickens

The poultry industry recently utilized locally abundant plant sources that are phytobiotics and environmentally friendly to improve production performance and boost the fowl’s immune system. However, plants may contain some anti-nutritive factors that might negatively affect the production performance. A total of sixty-day-old broiler chickens were used to investigate the potential of Moringa (Moringa oleifera Lam.) Pod Meal (MPM) on production performance and cell-mediated immunity. The broiler chickens were assigned in a Completely Randomized Design experimental set-up with four dietary treatments. Each treatment was replicated three times, with five birds in every replication and fed with MPM at 0 (T1), 5 (T2), 10 (T3), and 15% (T4) levels in 42 days feeding trial. Moringa pod meals’ chemical composition contains 13.02% crude protein, 36.98% crude fiber, 5.94% ash, and 11.33% moisture. The results revealed no significant differences (p>0.05) in the final weight, body weight gain, average daily gain, and feed conversion ratio of broiler chickens. Numerically, the highest final weight and weight gains were observed in birds fed with MPM. Moreover, the voluntary feed intake was significantly (p 0.05) observed in the indicators of cell-mediated immunity (immune organ indices), but numerical values showed higher in broiler chickens fed with MPM than broilers without MPM in the diet. The highest return of investment was observed in T3 with PhP106.48, and T1 obtained the lowest income generated with Php101.49 per bird. In light of the findings, incorporating MPM in the diets seems potential to improve broiler chickens production and immune responses, however further studies using large population of birds should be warranted.

CD4+ T cells dominate the leukocyte infiltration response initiated by intra-dermal injection of phytohemagglutinin into growing feathers in chickens

Phytohemagglutinin (PHA) is commonly used to evaluate cell-mediated immunocompetence. In chickens, PHA is typically injected intra-dermally (i.d.) into the skin (e.g., wing web, wattle, or footpad), and the tissue swelling response is monitored, whereby the extent of tissue swelling positively relates to the individual's cell-mediated immune system capabilities. Although i.d. injected PHA was shown to stimulate mononuclear cell and basophil infiltration to the site of injection, reports on temporal, qualitative, and quantitative aspects of the local cutaneous PHA response are limited. The objective of this study was to use the growing feather (GF) as a cutaneous test site to assess and monitor the type and relative amounts of leukocytes present in the pulp of PHA-injected GF. For this study, male, non-vaccinated Light-brown Leghorn chickens reared at the Arkansas Experiment Station Poultry Health Laboratory were used. At 9 wk of age, the dermis of 20 18-day-old regenerating GF was injected with 10 μL of either PBS diluent or 300μg/mL PHA-P (5 chickens per treatment). GF were collected from each chicken before (zero) and at 0.25, 1, 2, 3, 4, 5, and 7 d post injection. At each time point, one GF was collected for immunofluorescent staining of pulp cell suspensions and leukocyte population analysis by flow cytometry, and another GF for histological analysis. Histological analysis confirmed participation of granulocytes and mononuclear cells, primarily lymphocytes, in the cutaneous PHA response. As revealed by flow cytometric cell population analysis, T cells, especially CD4+ T cells, constituted the major portion of the mononuclear cell infiltrate. Levels of CD4+ T cells were greatly elevated in PHA-injected GF within 6h and remained elevated throughout the 7-day examination period. γδ T cells, CD8+ T cells, and B cells also infiltrated in response to PHA although at lower levels and with different time-course patterns from CD4+ T cells. The dominant presence of CD4+ T cells at the site of PHA injection further affirms this polyclonal response as an indicator of cell-mediated immunity.

Immune response and distribution of antigen in chickens after infection LPAIV (H4N6)

ObjectiveTo study the immune response in chicken on the administration ofLPAIV isolated from the natural reservoir.IntroductionInfluenza is a serious problem for the health of people, animals andbirds. Therefore, comprehensive study of influenza virus, its naturalreservoir, pathogenesis and immune response will provide furtheropportunity to ensure protection for animals, birds and people fromthis infection.MethodsFour-week-old commercial chickens were intranasally inoculatedwith a H4N6 LPAIV A/Garganey/Chervonooskilske/4-11/2009(H4N6), isolated from the cloacal swab of clinically healthy garganeyin 2009 in Ukraine. Cecum, spleen, lung, and trachea samples werecollected from infected chickens on 1 - 14 dpi and examined byimmunohistochemical and virology techniques. On these days,we collected blood samples for serological analysis. Detection ofantibodies to avian influenza virus subtype H4 was performed withchicken serum samples by HI test and ELISA. The studies were doneaccording to IACUC.ResultsUpon intravenous and intranasal infection with this virus(A/Garganey/Chervonooskilske/4-11/2009), no clinical signs wereobserved in chickens and no pathological changes were found atnecropsy. Infection of poultry with this virus provoked an antibodyresponse at 10 days after intranasal inoculation which ranged from1:8 to 1:32 serum antibody titers. Only 2 of 5 chickens were positiveby the HI test and 3 of 5 were positive by ELISA at intranasalinoculation. All 10 chickens were positive both by HI test and byELISA after intravenous inoculation. Specific antibodies (HI test) toinfluenza virus H4 were detected in titer ranges of 1:128 to 1:1024.In immunohistological studies, the respiratory tract organs (lungsand trachea) showed higher level of humoral immunity (IgM, IgG,IgA-expressing cells) in the lung compared to the trachea. Also,indicators of cell mediated immunity as measured by the CD4 andmacrophage markers were higher in LPAIV-infected chickens inthe lungs at 14 days post infection compared to uninfected chickens.Lymphocytes expressing CD8 were increased starting 7dpi.The chickens in the infected group showed 2 times higher levels ofCD8 cells compared to the control chickens. IFN-γtranscripts wereobserved in the AI-infected chickens starting at 7dpi that coincideswith the increasing level ofCD4 cells. The number of lymphocytes which secrete IL-2 andIL-15 in AI-infected chickens were in general 1.5 to 2 times highercompared to the uninfected chickens. In AIV-infected chickens, thelevel of cells expressing IFN-γ, IL-2, and IL-15 increased at 7-daysafter infection. The peak time coincided with a period of increasingCD8 cells. However, there was no significant difference in thesecytokine levels between the AIV-infected and uninfected groups.In the cecum, lower levels of CD4 cells were seen on 5 dpi butlevels slowly increased from 7 dpi to 14 dpi following AIV infection.In the ceca, a significant increase in the number of cells expressingIgM and IgG was found.LPAIV infection induced an increase in macrophages andlymphocytes expressing CD4 and CD8 in the spleen throughout theperiod examined in this study indicating their role in host responseto viral infection. The levels of macrophages in chickens of AIV-infected group were 2 times higher than the control after 1 dpi.ConclusionsAlthough infection with a LPAIV did not cause obvious clinicaldisease, viral replication was detected in the trachea and spleen andboth local and systemic cellular and humoral immune responses wereelicited in these LPAIV-infected chickens. Our results indicate thepotential possibility for infection of poultry with viruses isolated fromwild birds. But currently it is not completely known why some virusesfrom wild birds can cause infection in poultry, while others can not.Further study of the immune response will enable us to determine thefeatures of the pathogenesis of low pathogenic avian influenza.

Effects of maternal natural (RRR α-tocopherol acetate) or synthetic (all-rac α-tocopherol acetate) vitamin E supplementation on suckling calf performance, colostrum immunoglobulin G, and immune function

The objective of this study was to determine the effects of maternally supplemented natural- or synthetic-source vitamin E on suckling calf performance and immune response. In a 2-yr study, one hundred fifty-two 2- and 3-yr-old, spring-calving, Angus-cross beef cows were blocked by age, BW, and BCS into 1 of 3 isocaloric, corn-based dietary supplements containing 1) no additional vitamin E (CON), 2) 1,000 IU/d of synthetic-source vitamin E (SYN), or 3) 1,000 IU/d of natural-source vitamin E (NAT). Maternal supplementation began approximately 6 wk prepartum and continued until the breeding season. Colostrum from cows and blood from calves was collected 24 h postpartum for analysis of IgG concentration as an indicator of passive transfer and circulating alpha-tocopherol concentration. At 19 d of age, blood was collected from calves to determine the expression of CD14 and CD18 molecules on leukocytes. At 21 and 35 d of age, humoral immune response was measured by a subcutaneous injection, in the neck, with ovalbumin (20 mg; OVA) and blood samples collected weekly until d 63 of age to determine antibodies produced against OVA. At d 63 of age, calves were administered an intradermal injection of OVA (1 mg) in the neck to assess cell-mediated immunity, which was determined on d 65 of age by measuring nodule size with calipers. Circulating alpha-tocopherol concentrations were increased at both 24 h (P = 0.001) and at the day of initial OVA challenge (P < 0.001) in SYN and NAT compared with CON calves. No differences were detected (P > 0.05) for calf birth BW, ADG, or weaning BW. There were no differences (P > 0.05) in calf serum total IgG or cow colostrum total IgG at 24 h or presence of CD14 and CD18 receptors at d 19 of age. The NAT calves had a greater antigen response to OVA at d 63 than SYN calves (P = 0.01; treatment x day interaction). As an indicator of cell-mediated immunity to OVA, nodule size at 65 d of age was not affected (P = 0.92) by maternal dietary supplementation. In conclusion, calves suckling cows supplemented with natural- and synthetic-source vitamin E had increased circulating concentrations of alpha-tocopherol at 24 h, which appeared to continue throughout maternal supplementation; however, calf immune function and performance were not affected.

Steering orally induced deviation of xenogeneic immunity with exogenous cytokines in rats fed porcine proteins

Immune response to xenoantigens is a barrier to xenotransplantation. The objective of this study was to determine if rat cell-mediated immunity (CMI) and antibody (Ab) to discordant porcine xenoantigens could be suppressed by oral administration of porcine protein with adjunct systemic cytokine therapy. Based on principles of oral tolerance, it was hypothesized that: a. Feeding proteins from porcine blood mononuclear cells (PBMC) would induce a type 2 response, inhibiting CMI and type 1 Ab (associated with xenograft rejection) but increasing the amount of type 2 Ab. b. IL-4, a type 2 cytokine would exaggerate type 2 bias, enhancing immune deviation. c. IFN-γ, a type 1 cytokine was expected to down-regulate overall Ab production, but increase CMI and type 1 Ab. DA rats fed porcine proteins with or without subcutaneous and intraperitoneal injections of IFN-γ or IL-4 received PBMC by subcutaneous injection. Dermal delayed-type hypersensitivity to PBMC was the indicator of CMI. The IgG Ab to porcine proteins was quantified and type 2 (IgG 1 + IgG 2a) to type 1 (IgG 2b) Ab ratios indicated IR bias. Unfed, PBMC-challenged controls had a type 1 response bias but feeding PBMC induced a type 2 bias that suppressed CMI and type 1 Ab and increased type 2 Ab but not total IgG Ab. Contrary to the T H1/T H2 paradigm, IL-4 decreased oral-induced type 2 IR deviation and did not provide significant benefits relative to feeding alone. Treatment with IFN-γ prevented a switch to type 2 IR but feeding-induced suppression of CMI was not significantly compromised. The IFN-γ potently suppressed Ab, including, surprisingly, type 1 IgG isotypes. Contrary to the hypothesis tested, feeding Ag in combination with systemic delivery of recombinant IFN-γ apparently created an immunoregulatory environment most favorable to xenograft survival.

Antigen-specific lymphocyte proliferation and interleukin production in chickens immunized with killed Salmonella enteritidis vaccine or experimental subunit vaccines.

Lymphocyte proliferation and interleukin (IL)-2 and IL-6 levels in serum were measured as indicators of cell-mediated immunity after immunization of chickens with a commercial killed Salmonella enteritidis (SE) vaccine or experimental subunit vaccines of crude protein (CP) extract or the outer membrane protein (OMP). Significantly increased proliferative responses to SE flagella, but not lipopolysaccharide, porin, CP, or OMP, were observed at 1 wk postimmunizarion in the three vaccination groups. The responses to flagella were specific because flagella-induced proliferation was not seen in chickens immunized with adjuvant alone. Of the three immunization protocols, use of the killed SE vaccine appeared most effective because it induced higher flagella-stimulated lymphocyte proliferation at 1 and 2 wk postvaccination compared with the CP- and OMP-vaccinated groups. Significantly increased IL-2 and IL-6 levels in serum were seen at 1 wk postimmunization in the three vaccination groups compared with adjuvant alone, but there were no differences between the killed vaccine and the subunit vaccines at this time, and the levels of both lymphokines returned to baseline at 2 wk postimmunization. We conclude that cell-mediated immunity to SE after vaccination with the killed bacterial vaccine or subunit vaccines is transient and mainly limited to flagella.

Cell-mediated immunity in merino lambs with genetic resistance to Haemonchus contortus

Lymphocyte proliferation and skin hypersensitivity responses to parasite antigens were measured as indicators of cell-mediated immunity in genetically resistant and random-bred lambs following infection with Haemonchus contortus. Responses of PBMC to the mitogens PHA, PWM and LPS were also assessed to determine if infection was associated with suppression of general immune function. All lambs demonstrated significant antigen-specific lymphocyte proliferation prior to experimental infection. The responses did not differ between resistant and randombred lambs and the correlation between pre-infection stimulation indices and resistance to challenge infection was also not significant. Following infection, PBMC from resistant lambs consistently exhibited higher blastogenic responses to both larval and adult antigens than PBMC from random-bred lambs. Addition of cyclosporin A to the antigen-stimulated cultures resulted in significant inhibition of blastogenesis, suggesting that the cells responding to parasite antigens were predominantly of the T-helper cell phenotype. Proliferation responses of resistant and random-bred sheep were similar for all mitogens tested. However, a transient suppression of lymphocyte reactivity to PHA and PWM was noted in all infected lambs. Responses to LPS remained unaffected during infection. There was no difference in the immediate hypersensitivity responses to intradermal inoculation of parasite antigens between the genotypes. However, the delayed-type hypersensitivity responses to parasite antigens were significantly greater in resistant lambs than those in random-bred lambs. Together, these data suggest that resistant lambs have an enhanced ability to mount parasite-specific cell-mediated immune responses when compared with randombred lambs and that this may contribute to differences in the susceptibility of two genotypes to haemonchosis.

Epidemiological Immunological Studies on Leprosy in Okinawa

Lepromin reactions of leprosy patients in the mainland and Okinawa of Japan were examined by using the standard (160 million bacilli/ml) and diluted lepromins, for the pur-pose of establishing practical use of the latter and understanding immunological character-istics of leprosy in Okinawa. The size of reactions expressed by mm scale were con-verted by common logarithms for statistical evaluation, because the distribution curves shown in Fig. 1-3 were approximately equal to a distorted shape of normal distribution. The results were as follow.1. Both Fernandez' and Mitsuda's reactions to the lepromins diluted in 1:4 or more were significantly weaker than those to the standard, as demonstrated by the percentage of completely negative (0-1mm) reactions (Tables 1 and 2) and by the difference between two reactions in both forearms of the same patient (Tables 7 and 8).2. Average size of reactions of the patients in Okinawa was significantly larger than those in the mainland, irrespective of dilution degree of the lepromins (Tables 4 and 5).3. A correlation coefficient was significant between the Fernandez' and Mitsuda's reactions to each of the standard, 1:4 and 1:8 diluted lepromins (Table 9).4. Normal human, autoclaved skin suspension caused the cutaneous response resembling Fernandez' reaction in a significant number of the patients, but the most of their responses disappeared completely after 4 weeks and a mean size of reactions in a few cases was significantly smaller than that of Mitsuda's reactions (Tables 3, 6 and 7).5. Significant fall in the percentage of completely negative reactions and significant increase in the mean of 2mm or larger sizes of ractions were observed in the patients with lepromatous leprosy, according to three stages which were classified as progressive, retrogressive and quiescent in this order (Table 10).6. A cut-off point of positive Fernandez' reactions was proposed to be 8mm, according to different criteria for positive reactions in lepromatous cases as well as in non-lepro-matous. On the other hand, Mitsuda's reactions should rather be recorded by the size of reaction which could be used as an indicator of cell-mediated immunity against Mycobacterium leprae.

An immunotoxicological evaluation of γ-chlordane

Various toxicological and immunological parameters were assessed after exposure of female B6C3F1 mice to 0.1, 1.0, 4.0, and 8.0 mg/kg γ-chlordane for 14 days via oral gavage. Variables evaluated included periodic body weights, terminal organ weights, hematology including leukocyte differentials, antibody response to sheep red blood cells (SRBC), lymphoproliferative responses to the mitogens phytohemagglutinin (PHA), concanavalin A (Con A), and lipopolysaccharide (LPS) and allogeneic cells, and the delayed hypersensitivity response (DHR) to keyhole limpet hemocyanin (KLH). When compared to the corn oil (vehicle) controls, chlordane produced a significant, dose-related increase in liver weight. Total leukocytes were significantly increased in chlordane-treated groups and seemed to be due to a significant increase in the lymphocyte population. Humoral immunity (HI), as assessed by enumeration of SRBC-specific immunoglobulin M (IgM) antibody forming cells (AFC) and proliferation of LPS-stimulated spleen cells, was not significantly altered in mice exposed to chlordance. In vitro evaluation of cell-mediated immunity (CMI), as measured by proliferation of Con A and PHA-stimulated spleen cells from chlordane-treated animals, indicated a significant and dose-related increase. The response to allogeneic cells was also enhanced. Results from an in vivo indicator of cell-mediated immune status, the delayed hypersensitivity response to KLH, did not support chlordane-enhanced T cell function suggested by mitogen and mixed lymphocyte responses. Therefore, a potent cyclodiene insecticide of environmental concern produced an enhancement of certain indicators of CMI. The expression of a DHR in vivo and the antibody response to SRBC was unaltered in mice exposed to the chemical. These results suggest that γ-chlordane, at the concentrations utilized, does not produce a biologically significant alteration of the immunocompetence of intact animals.

An Immunotoxicological Evaluation of γ-Chlordane

Various toxicological and immunological parameters were assessed after exposure of female B6C3F1 mice to 0.1, 1.0, 4.0, and 8.0 mg/kg gamma-chlordane for 14 days via oral gavage. Variables evaluated included periodic body weights, terminal organ weights, hematology including leukocyte differentials, antibody response to sheep red blood cells (SRBC), lymphoproliferative responses to the mitogens phytohemagglutinin (PHA), concanavalin A (Con A), and lipopolysaccharide (LPS) and allogeneic cells, and the delayed hypersensitivity response (DHR) to keyhole limpet hemocyanin (KLH). When compared to the corn oil (vehicle) controls, chlordane produced a significant, dose-related increase in liver weight. Total leukocytes were significantly increased in chlordane-treated groups and seemed to be due to a significant increase in the lymphocyte population. Humoral immunity (HI), as assessed by enumeration of SRBC-specific immunoglobulin M (IgM) antibody forming cells (AFC) and proliferation of LPS-stimulated spleen cells, was not significantly altered in mice exposed to chlordane. In vitro evaluation of cell-mediated immunity (CMI), as measured by proliferation of Con A and PHA-stimulated spleen cells from chlordane-treated animals, indicated a significant and dose-related increase. The response to allogeneic cells was also enhanced. Results from an in vivo indicator of cell-mediated immune status, the delayed hypersensitivity response to KLH, did not support chlordane-enhanced T cell function suggested by mitogen and mixed lymphocyte responses. Therefore, a potent cyclodiene insecticide of environmental concern produced an enhancement of certain indicators of CMI. The expression of a DHR in vivo and the antibody response to SRBC was unaltered in mice exposed to the chemical. These results suggest that gamma-chlordane, at the concentrations utilized, does not produce a biologically significant alteration of the immunocompetence of intact animals.

Alterations in the cellular immune response of patients with cerebral glioma, benign intracranial tumour, and spontaneous subarachnoid haemorrhage measured in vitro by the leucocyte migration inhibition test.

Leucocyte migration inhibition in response to ubiquitous antigens was studied in 104 patients as an in vitro indicator of cell-mediated immunity. Patients with cerebral glioma, benign intracranial tumours, and subarachnoid haemorrhage demonstrated impaired inhibition of leucocyte migration compared with control subjects. The greatest impairment occurred in patients with subarachnoid haemorrhage, while the least impairment was seen in patients with glioma. Significant rises in inhibition of leucocyte migration in response to antigen preparations from glioma and normal brain were seen in the early post-operative period in patients with glioma and subarachnoid haemorrhage. Impaired cellular immunity, together with sensitivity of lymphocytes to brain-derived antigens, are features of cerebral disease in general and not specific for glioma.

HLA-B8 and cell-mediated immunity to gluten.

The leucocyte migration inhibition (LMI) test was used as an indicator of cell mediated immunity to gluten fraction III in 30 healthy controls and 58 patients with adult coeliac disease and the results related to HLA status and duration of treatment with a gluten-free diet. HLA-B8 controls showed significantly lower leucocyte migration indices, indicating greater immune response, than non-HLA B8 controls. Untreated coeliacs showed no difference from HLA-B8 controls. There was no difference between results from HLA-B8 and non-HLA-B8 coeliacs. Leucocyte migration was even lower in coeliacs early in treatment but rose after treatment for over one year. These results may reflect an immune response gene for gluten in linkage disequilibrium with HLA-B8. The increased immune response to gluten as measured in this test cannot be the sole factor in aetiology of coeliac disease. Furthermore, it is necessary to re-evaluate earlier results of cell-mediated immunity in coeliac disease with reference to HLA status of the controls.

EFFECT OF LIPOPOLYSACCHARIDE ON THE DEVELOPMENT OF CELL-MEDIATED IMMUNITY TO TRANSPLANTATION ANTIGENS

Lipopolysaccharide (LPS) from Escherichia coli administered to allografted mice in a single dose of 20 microgram influenced the development of cell-mediated immunity to skin donor antigens. As an indicator of cell-mediated immunity, donor antigen-induced inhibition of cell migration from spleen explants of allografted animals was used. Cultures of spleen explants were established 16 days after grafting. The antigen-specific inhibition of migration was abolished when LPS was injected either 4 to 2 days before grafting and intensified when LPS was administered on the 2nd day after grafting.

Studies on Pasteurella multocida. III. In Vitro Assay for Cell-Mediated Immunity

Peripheral blood lymphocytes (PBL) from turkeys immunized against fowl cholera with a bacterin or a live avirulent vaccine (strain CS-148) were cultured in vitro with various antigenic preparations from Pasteurella multocida (strain P-1059). The degree of lymphocyte stimulation (blastogenesis) was quantitated by measurement of the uptake of (3H) thymidine. Higher stimulation indices were obtained with immune lymphocytes rather than nonimmune lymphocytes. Stimulation was specific since PBL from turkeys immunized against P. multocida failed to react with Escherichia coli or Mycoplasma synoviae antigens. These differences were statistically significant as analyzed with the student's t-test. The lymphocyte transformation assay was emphasized as a convenient and useful in vitro indicator of cell-mediated immunity that should help define the role of cell-mediated immunity in P. multocida infections of turkeys.

Leucocyte migration inhibition as a indicator of cell mediated immunity in chickens

The influence of purified protein derivative of tuberculin upon the in vitro migration of peripheral leucocytes of birds sensitized with either (a) heat killed Mycobacterium tuberculosis in Freund's adjuvant or (b) viable Mycobacterium avium was investigated. Migration inhibition was demonstrated in both types of birds and compared with uninoculated controls. A detailed description of the method adopted and a list of features found necessary for the production of consistent reproducible results is given. The results correlated well with intradermal skin tests and indicated that the leucocyte migration inhibition test is a practical and reproducible method of studying the role of cellular immunity in chickens. The possible application of the test to other diseases of poultry is discussed.

Leucocyte migration inhibition as a indicator of cell mediated immunity in chickens

Summary The influence of purified protein derivative of tuberculin upon the in vitro migration of peripheral leucocytes of birds sensitized with either (a) heat killed Mycobacterium tuberculosis in Freund's adjuvant or (b) viable Mycobacterium avium was investigated. Migration inhibition was demonstrated in both types of birds and compared with uninoculated controls. A detailed description of the method adopted and a list of features found necessary for the production of consistent reproducible results is given. The results correlated well with intradermal skin tests and indicated that the leucocyte migration inhibition test is a practical and reproducible method of studying the role of cellular immunity in chickens. The possible application of the test to other diseases of poultry is discussed.

Leukocyte migration inhibition in chorioretinitis.

Leukocyte migration inhibition (LMI) by choroid, retina, and uveal tract antigens was studied in patients with active and quiescent chorioretinal disease. LMI by retina was more frequent in both groups of patients, occurring in 9 of 16 patients with active disease and in 8 to 15 patients with disease in remission. Choroid was tested in 15 patients with active inflammation and led to LMI in 7 of them when they were off steroid therapy; it produced LMI in 3 of 13 patients whose disease appeared healed. Significant LMI was detected in three of six patients with active chorioretinitis and in one of five patients with evidence of past chorioretinopathy when their cells were tested with antigen made from pooled uveal tract tissue. The LMI test, regarded as an indicator of cell-mediated immunity, is briefly discussed. LMI by retina in over one-half of patients with chorioretinopathies appears to be a secondary event, and cellular immunity to retina may be of pathophysiological importance in the chronicity of the disorder.