Mitogen-induced Lymphoproliferation Research Articles

Herpes Zoster: Hand Dominance the Missing Link to Unilaterality?

Sir, Herpes zoster (HZ) occurs as reactivation of varicella zoster virus following primary infection or vaccination. It is classically unilateral in its presentation appearing along the distribution of the cranial or spinal sensory nerves, with an occasional spill into the neighboring dermatomes. Rarely, it may be bilateral or disseminated. Affliction of a dermatome depends on the viral load in that region during the viremia of varicella. Appearance of many patients with left-sided dermatome involvement led us to evaluate HZ cases presenting to our skin center at a tertiary care hospital. A prospective study over a period of 1 year from January 1 to December 31, 2013 was conducted on patients presenting at either the outpatient department or admitted either for HZ or had developed it in addition to their primary disease, considering a null hypothesis that there was no relationship between the side affected and the hand dominance of the patient. Of a total of 84,835 patients reviewed at the skin center in the study period, 457 (0.54%) had HZ. Males 260 (57%) and females 197 (43%) accounted for the total cases. Maximum number of patients were between 20 and 40 years (72%, 339), followed by those between 40 and 60 years (24%, 113) and more than 60 years (3%, 14), with the least <20 years of age (1%, 5). Most right-handed patients manifested HZ on the left side (61%) [Table 1]. The right-handed individuals accounted for 95% of the total cases. Of the left-handed, 62% manifested HZ on the right side [Figure 1]. Statistical analysis with Fisher's test revealed a two-tailed P = 0.0302 proving a statistically significant involvement of the contralateral side in HZ compared to hand dominance.Table 1: Distribution of herpes zoster side with hand dominanceFigure 1: Herpes zoster and area of involvementDermatome involvement in HZ has been explained based on higher regional viremia during varicella, with the most common dermatomes consistently reported in the thoracic region, as was in our case.[12] Unilaterality in HZ, however, is not yet fully explained. It has been postulated that the two sides of the brain may be differently involved in the modulation of immune responses.[3] Lesions of right or left neocortex-induced opposite effects on various immune parameters including mitogen-induced lymphoproliferation, interleukin-2 production, macrophage activation, or natural killer cell activity in rodents.[4] Cell-mediated hypersensitivity has also been reported to be higher on the involved side of HZ.[5] Primarily left-sided involvement in larger series of HZ has been reported, with Ertunç et al. reporting greater incidence of the left side of the body affected in the right-handed females.[6] Psychiatric, medical, and neurological disorders are increasingly showing a consistent relationship to handedness.[7] Hand dominance is usually determined, as in this series, by the predominant side used for skilled motor actions, such as writing. Left-hand dominance is reported to be 13–20% of the general population, which was lower at 5% in our study population. However, reports of handedness and cerebral dominance have been reported to be variable as although more than 90% of right-handed individuals have left brain dominance for language and motor skill so are about 70% of left-handed individuals.[8] Prevalence of this left hemispherical dominance possibly explains why 38% of our left-handed cases still manifested HZ on the left side rather than their contralateral side. None of our cases was ambidextrous. This series to the best of our knowledge is the largest series of HZ which demonstrates hand dominance and contralateral eruption of HZ. Thus, it reflects that cerebral dominance plays an important role in neuroimmunomodulation, thus affecting the immune responses of the skin of the contralateral half of the body.[9] Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Astaxanthin decreased oxidative stress and inflammation and enhanced immune response in humans

BackgroundAstaxanthin modulates immune response, inhibits cancer cell growth, reduces bacterial load and gastric inflammation, and protects against UVA-induced oxidative stress in in vitro and rodent models. Similar clinical studies in humans are unavailable. Our objective is to study the action of dietary astaxanthin in modulating immune response, oxidative status and inflammation in young healthy adult female human subjects.MethodsParticipants (averaged 21.5 yr) received 0, 2, or 8 mg astaxanthin (n = 14/diet) daily for 8 wk in a randomized double-blind, placebo-controlled study. Immune response was assessed on wk 0, 4 and 8, and tuberculin test performed on wk 8.ResultsPlasma astaxanthin increased (P < 0.01) dose-dependently after 4 or 8 wk of supplementation. Astaxanthin decreased a DNA damage biomarker after 4 wk but did not affect lipid peroxidation. Plasma C-reactive protein concentration was lower (P < 0.05) on wk 8 in subjects given 2 mg astaxanthin. Dietary astaxanthin stimulated mitogen-induced lymphoproliferation, increased natural killer cell cytotoxic activity, and increased total T and B cell subpopulations, but did not influence populations of Thelper, Tcytotoxic or natural killer cells. A higher percentage of leukocytes expressed the LFA-1 marker in subjects given 2 mg astaxanthin on wk 8. Subjects fed 2 mg astaxanthin had a higher tuberculin response than unsupplemented subjects. There was no difference in TNF and IL-2 concentrations, but plasma IFN-γ and IL-6 increased on wk 8 in subjects given 8 mg astaxanthin.ConclusionTherefore, dietary astaxanthin decreases a DNA damage biomarker and acute phase protein, and enhances immune response in young healthy females.

In vitro pharmacological screening of macrofungi extracts from the Brazilian northeastern region

Although the use of macrofungi in popular medicine is very common, especially in East Asia, the knowledge about their pharmacological properties is poorly investigated. The aim of this work was to evaluate the pharmacological potential of six species of macroscopic fungi: Phellinus rimosus (Berk.) Pilát (Hymenochaetaceae), Pycnoporus sanguineus (L.) Murrill (Poyporaceae), Hymenochaete rheicolor (Mont.) Lév. (Hymenochaetaceae), Hexagonia papyracea Berk. (Polyporaceae), Datronia caperata (Berk.) Ryvarden (Polyporaceae), and Lepiota sp. (Agaricaceae), collected in the state of Bahia, in north-eastern Brazil. Extracts of these species were obtained and tested to determine their cytotoxicity in normal mouse spleen cells. Immunomodulatory, antineoplasic and antiparasitic activities were investigated. Four macrofungi extracts (Phellinus rimosus, Hymenochaete rheicolor, Lepiota sp., and Datronia caperata) inhibited the lymphoproliferative response stimulated by concanavalin A in 65–96% of inhibition in mitogen-induced lymphoproliferation assay, three (Hymenochaete rheicolor, Pycnoporus sanguineus, and Lepiota sp.) inhibited 60–70% of production of nitric oxide by J774 activated by IFN-γ and LPS, and two (Phellinus rimosus and Pycnoporus sanguineus) had antimalarial activity against chloroquine-resistant Plasmodium falciparum (over 60%). We did not find inhibition greater than 60% to the growth of both Leishmania amazonensis and Trypanosoma cruzi. To our knowledge, this is the first description of immunomodulatory activity of Hymenochaete rheicolor (HR), Datronia caperata (DC) and Pycnoporus sanguineus (PS). These results indicate that macrofungi species from the Brazilian north-east have pharmacological activity and are thus a potential source of natural products with medicinal interest.

T lymphocyte proliferative capacity and CD4+/CD8+ratio in primiparous and pluriparous lactating cows

T cells play a central role in specific immunity; their populations and phenotypes could be affected by number of lactation in high-yielding dairy cows. To investigate the effects of parity on the dynamics of T lymphocytes, lymphoproliferative capacity, T lymphocyte subsets and CD4+/CD8+ ratio were studied in peripheral blood of primiparous and pluriparous dairy cows during mid-late lactation. A non-radioactive technique was also adapted for a detailed lymphoproliferation assay. Compared with the primiparous cows, the pluriparous cows exhibited weaker lymphoproliferative activity, larger number of CD4+ cells and substantially greater CD4+/CD8+ ratio in their blood circulation. The increase of the CD4+/CD8+ ratio in the blood of pluriparous dairy cows was mainly due to the rise in the proportion of CD4+ cells and decline in the proportion of CD8+ cells. This increase of the CD4+/CD8+ ratio coincided with the decrease of mitogen-induced proliferation capacity of T lymphocytes. Of four lymphocyte divisions or generations during the lymphoproliferation assay, maximal lymphocyte proliferation capacity at generation 3 in primiparous cows was markedly greater than in pluriparous cows. With an alternatively safer, faster and more reproducible assay (compared with 3H-thymidine scintillation assay) we showed for the first time that aging in dairy cows leads to a decreased mitogen-induced lymphoproliferation and disturbed proportion between CD4+ and CD8+ T cells. This CD4+-CD8+ imbalance together with diminished lymphoproliferative capacity may lead to a weaker T cytotoxic-mediated immunity and increased susceptibility to infectious diseases in pluriparous lactating cows. Our study also emphasizes further application of the methods in farm animals.

Changes in leucocyte populations following murine bifunctional antibody infusion in colon cancer patients

This study was undertaken to determine whether infusion of a unique ZCE/CHA bifunctional antibody (BFA, 5-40 mg) could alter the composition and functions of peripheral blood leucocytes in 18 patients with colon cancer. The BFA is made by combining chemically the Fab' fragments of two murine monoclonal antibodies. One fragment (ZCE 025) binds to the carcino-embryonic antigen (CEA) and the other (CHA 225) to an epitope, present on an 111In-benzyl EDTA analog of bleomycin (BLEDTA IV) and on 111In-hydroxy-ethyl-thiourea benzyl EDTA (EOTUBE). The radiolabelled epitope (111In-BLEDTA IV or 111In-EOTUBE) was given 4 days after prelocalization with BFA. Peripheral blood samples were tested before BFA infusion, at the end of infusion (1 h later), and at 4 and 7 days post-infusion. A 50% or greater suppression in lymphocyte responsiveness to phytohaemagglutinin (PHA) and concanavalin A (Con A) was seen in 13 out of 18 and 12 out of 18 subjects, respectively, at some time after BFA infusion; this was especially evident in those patients with pre-infusion stimulation indices of greater than 50 (PHA) and/or greater than 10 (Con A). In contrast, natural killer (NK) cell cytotoxicity and oxygen radical production increased in five out of 15 and in seven out of 18 subjects, respectively. Little or no change was observed in CD3, CD4, CD8, CD16, and CD19 markers on lymphocyte subpopulations as determined by flow cytometry. These data suggest that significant changes in mitogen-induced lymphoproliferation. NK cell cytotoxicity, and oxygen radical production can occur in a substantial proportion of cancer patients after infusion of the ZCE/CHA bifunctional antibody system. The immunomodulation was unrelated to initial BFA dose, dose of BFA as a carrier, or to subsequent infusion of either form of the 111In epitope. The clinical significance of these phenomena, if any, remains to be determined.

Extracellular organelles (prostasomes) are immunosuppressive components of human semen

Numerous reports have ascribed immunosuppressive activity to human seminal plasma and there is growing agreement that much of this activity can be accounted for by the very high levels of E series prostaglandins present (up to 300 microM 19-hydroxy prostaglandin E). However not all suppressive activity is due to prostaglandin since several reports have appeared of high molecular weight active substances and we have found that stripped seminal plasma is still effective in inhibiting the mitogen-induced proliferation of lymphocytes. In this study such immunosuppressive activity has been separated by molecular size fractionation and the activity has been found to be particulate and corresponded to the previously reported prostasomes. These are trilaminar to multilaminar vesicles (150 nm diameter) which are secreted by the prostate. Pure preparations of prostasomes inhibited mitogen-induced lymphoproliferation in a dose-dependent manner with a concentration of prostasomes equivalent to 40% of that seen in seminal fluid giving 69% suppression of thymidine incorporation. The suppressive activity survived boiling and therefore was unlikely to be due to enzymatic action associated with these organelles. Interaction with the accessory cells, involved in full development of the lymphoproliferation induced by mitogen, was indicated and this possibility was supported by the demonstration of a direct effect of prostasomes on macrophage function using a mouse macrophage cell line. The prostasomes in semen may play a complementary role to the prostaglandins in neutralizing the immune defences of the female reproductive tract. This combination would allow the alloantigenic spermatozoa the best chance of achieving fertilization, but at the same time leave the recipient open to any infection present in the semen.

Caloric Restriction Decreases Survival of Aged Mice in Response to Primary Influenza Infection

Caloric restriction (CR) extends life span of healthy rodents compared to those fed ad libitum. Previous studies have shown positive effects of CR on the immune response of aged mice after influenza immunization. To extend these studies, a mouse model of CR was used to determine if CR could modulate primary responses of aged mice to influenza. Although CR delayed the age-related decrease in mitogen-induced lymphoproliferation of aged mice, in stark contrast, CR decreased survival, increased virus titers, and reduced natural killer cell activity in lungs of aged mice after primary influenza infection. Thus, CR has differential effects on immunity of aged mice, as general indices of immune response are maintained, but primary responses to influenza infection are impaired. This suggests that, although CR may positively affect many long-term parameters of aging, increased susceptibility after primary exposure of aged mice to virus, such as influenza, may not be correctable by CR.

Kinetics of early FIV infection in cats exposed via the vaginal versus intravenous route.

To determine the influence of route of virus exposure on early pathogenesis of feline immunodeficiency virus (FIV) infection, cats were exposed to either of two FIV isolates (FIV-B-2542 or FIV-A-PPR) by vaginal or intravenous (IV) inoculation. Exposure to either virus clade by either route of inoculation resulted in vaginal and systemic infection. Peak plasma viremia and tissue proviral burden were 1-3 log(10) greater in cats infected with FIV-B-2542 vs. FIV-A-PPR, irrespective of inoculation route. Plasma RNA levels paralleled provirus titers in FIV-B-2542-infected cats and were highest in those exposed IV. In contrast, plasma RNA titers were higher in cats infected vaginally with FIV-A-PPR than in those infected IV. Despite early differences, PBMC provirus titers were similar in all groups by 9 weeks postinfection. In cats infected IV, but not vaginally, CD4(+) lymphocyte counts declined significantly independent of the magnitude of viremia. Mitogen-induced lymphoproliferation was decreased in all infected cats regardless of CD4(+) cell counts; this decline correlated with the magnitude of peak plasma viremia in FIV-B-2542, but not FIV-A-PPR, infected cats. These results establish that the kinetics of early FIV infection differ with route of exposure as well as virus isolate and that properties extrapolated from one virus isolate may not be universal.

Suppression of Restraint-induced Plasma Cytokines in Mice Pretreated With LPS

A previous exposure to an inflammatory reaction is known to increase or decrease the activation of the hypothalamic-pituitary-adrenal (HPA) axis induced by a psychological/physical stress. Beside HPA activation, the non- specific responses to these two kinds of stresses involve the immune system including the production of cytokines. Therefore, they could interfere in cytokine production. In order to test this hypothesis, female C3H mice were first injected i.p. with 5 w g of lipopolysaccharide (LPS) or not (C). Eight days later, half of them were submitted to a 4 h-restraint (R) applied during the nocturnal part of the dark-light cycle and sacrificed immediately after (groups LPS-R and C-R), while the non restrained mice stayed in their home cages (groups LPS-C and C-C). Restraint induced an increase in corticosterone production that was not altered by the previous administration of LPS. It had no effect on mitogen-induced lymphoproliferation. However, restraint induced an augmentation of plasma concentrations of interleukin (IL)-1 and IL-6 that was not observed in animals previously exposed to LPS. These results show that restraint, which represents a psychological stress is able to induce the production of plasma cytokines in mice. They also suggest that LPS may induce a long lasting suppression of plasma cytokines through mechanisms that remain to be elucidated.

A novel immunosuppressant, FTY720, induces peripheral lymphodepletion of both T- and B cells and immunosuppression in baboons

Objective: FTY720, a new immunosuppressant active in transplantation models, modulates lymphocyte re-circulation, leading to peripheral lymphopenia and increased lymphocytes in lymph nodes and Peyer's patches. Here, we investigated the susceptibility of baboons to FTY720 as an introductory study to transplantation protocols. Methods: FTY720 was administered orally to Chacma baboons at 0.3 or 0.1 mg/kg/day for 3 days or at 0.03 mg/kg/day for 10 days. Haematological parameters, lymphocyte phenotype (CD3, CD4, CD8, CD20), cell apoptosis, ex vivo blood cell proliferation in response to mitogens and drug blood levels were monitored during treatment and up to 4 weeks thereafter. Main findings: FTY720 administered p.o. in baboons at 0.3 mg/kg/day caused a marked decrease in circulating lymphocytes within 4 h of treatment, reaching 60–80% decrease within 24–48 h. The effect of FTY720 was seen both on T- and B cells, although it was slightly more rapid/pronounced on T cells. CD4 + cells were slightly more affected than CD8 + cells. The response onset was faster and the duration longer at higher dose, but the maximal peripheral lymphodepletion achieved was similar within the dose range 0.03–0.3 mg/kg tested. Ex vivo mitogen-induced lymphoproliferation was drastically decreased after FTY720 treatment, corresponding to the reduced blood lymphocyte counts. The blood drug levels measured after FTY720 administration correlated well with the dose applied but there was a poor correlation between FTY720 blood levels and the extent of peripheral lymphodepletion, suggestive of a high tissue distribution of the drug. When compared with cynomolgus monkeys treated in the same way, baboons had a lower initial exposure and a slightly lower response 24 h after one or two doses of FTY720 0.03–0.3 mg/kg. However, the stabilized drug blood levels and peripheral lymphodepletion achieved after 7 days of FTY720 0.03 mg/kg/day were similar in both nonhuman primate species. Conclusions: FTY720 was well tolerated and was effective in terms of peripheral T- and B lymphodepletion in baboons, indicating that it could be used in protocols of allo- and xenotransplantation. The pharmacokinetic and pharmacodynamic profiles of FTY720 in baboons suggest the use of high induction doses to optimize immediate response followed by a reduced dose regimen for drug maintenance.

Attachment ligands of viable Toxoplasma gondii induce soluble immunosuppressive factors in human monocytes.

Previous studies have demonstrated that surface antigen proteins, in particular SAG-1, of Toxoplasma gondii are important to this parasite as attachment ligands for the host cell. An in vitro assay was developed to test whether these ligands and other secretory proteins are involved in the immune response of human cells to toxoplasma. Human monocytes were infected with tachyzoites in the presence of antiparasite antibodies, and their effect on mitogen-induced lymphoproliferation was examined. The presence of antibody to either parasite-excreted proteins (MIC-1 and MIC-2) or surface proteins (SAG-1 and SAG-2) during infection neutralized the marked decrease seen in mitogen-induced lymphoproliferation in the presence of infected monocytes. Conversely, antibodies to other secreted proteins (ROP-1) and cytoplasmic molecules had no effect on parasite-induced, monocyte-mediated downregulation. Fluorescence microscope analysis detected microneme and surface antigen proteins on the monocyte cell surface during infection. These results suggest that microneme and surface antigen proteins trigger monocytes to downregulate mitogen-induced lymphoproliferation.

Suppression of immunoglobulin secretion by soluble annexin II.

Annexin II (AII) belongs to a family of glycoproteins that bind negatively charged phospholipids in the presence of calcium. The annexins exert various biological functions. We have previously shown that soluble AII suppresses mitogen-induced lymphoproliferation in vitro. In this study we address the question of whether soluble AII may also affect immunoglobulin secretion. Mononuclear cells from peripheral blood were stimulated with pokeweed mitogen in vitro and immunoglobulin-secreting cells were quantified using an ELISPOT assay. Retroplacental serum and soluble AII significantly inhibited secretion of IgG and IgM when added at concentrations that did not affect lymphoproliferation or cell viability. The inhibitory effect was dose- and time dependent. Significant suppression was observed when soluble AII was added at concentrations of 0.1 and 0.01 microg/ml. The strongest inhibition was observed when soluble AII or retroplacental serum was added initially. The data demonstrate that soluble AII can suppress immunoglobulin secretion in vitro. AII seems to be a potent immunosuppressive substance. The presence of high levels of soluble AII in retroplacental serum may indicate a possible immunomodulatory role in normal pregnancy.

Characteristic immune abnormalities in hemophagocytic lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening syndrome characterized by fever, hepatosplenomegaly, pancytopenia, and infiltration of vital organs by non-Langerhans histiocytes and is rapidly fatal without early diagnosis and institution of therapy. Immune dysregulation is thought to be responsible for the disease. Extensive immune evaluation was performed on 13 consecutive patients diagnosed with HLH over a 4-year period to characterize existing immunologic abnormalities in order to improve early diagnosis. Evaluation included quantitative immunoglobulins, immunophenotyping, mitogen-induced lymphoproliferation, natural killer (NK) cell function, and cytotoxic T cell lymphocytolysis (CTL). Immunoglobulin levels showed no consistent abnormality. Immunophenotyping showed an absolute decrease in number of B cells but normal numbers and proportional distribution of T cell subsets and NK cells. Most patients demonstrated decreased proliferative responses to mitogens (10/13) and severely decreased to absent T cell cytotoxicity (11/12) and NK cytotoxic function (13/13). Our results show that while humoral immunity is essentially intact, cellular immune function is significantly impaired in the vast majority of patients with HLH. The coincident finding of profoundly decreased T cell cytotoxicity along with absent NK cytotoxicity suggests that patients with active HLH may have global cytotoxic dysfunction. Since the majority of our patients were studied prior to starting therapy, we feel that these findings reflect the pathophysiologic process and are not therapy related. Unclear from the present work is whether these findings represent primary or secondary dysfunction. We conclude from these studies that profoundly decreased CTL function and absence of NK cell function are characteristic immunologic features of HLH and may serve as additional laboratory data, in conjunction with currently proposed diagnostic guidelines, to support a diagnosis of HLH.

Persistence of decreased T-helper cell function in industrial workers 20 years after exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin.

In experimentally exposed animals 2,3,7,8-tetrachlorodibenzo-n-dioxin (TCDD) causes severe immunosuppression. However, the overall susceptibility of humans for the different pathological effects of TCDD has remained unclear. We examined the long-term effects of TCDD in 11 industrial workers who were exposed to high doses of TCDD for several years 20 years ago. Current TCDD body burdens were still at least 10 times higher (between 43 and 874 pg/g blood far) in these exposed persons than in the average German population. To evaluate possible TCDD-induced changes in the percentage of different lymphocyte subsets, we determined a large panel of lymphocyte subsets in the blood by flow cytometric analysis. Immunocompetence of T-and B-lymphocytes was tested by nitrogen (phytohemagglutinin, pokeweed mitogen)- induced lymphoproliferation assays and by assays using sensitive mixed-lymphocyte cultures. No significant differences could be detected between the individuals tested and controls for surface marker distribution or mitogen-induced lymphoproliferation TCDD-exposed subjects showed a reduced response to human lymphocyte antigen-allogeneic lymphocytes and interleukin-2-boosted proliferation. Responder cells of the dioxin-exposed persons proliferated less in response to irradiated stimulator cells (p < or = 0.05), and the third-party mixed lymphocyte reaction against unirradiated stimulator cells revealed suppressive activity in the responder cell fraction compared to the controls (p < or = 0.01). Furthermore, the capacity of a pool of T cells isolated from TCDD-exposed subjects to proliferate upon interleukin-2 stimulation was significantly diminished (p < or = 0.05). TCDD has a long-term immunosuppressive-effect on T-helper cell function, which is mediated more likely by a reduced functionality of individual cells rather than by a reduction in absolute cell numbers in the peripheral blood.

Effect of the microsporidian Enterocytozoon salmonis on the immune response of chinook salmon

The protozoan parasite Enterocytozoon salmonis is an intranuclear microsporidian of salmonid mononuclear leukocytes. Experimental infections were initiated in chinook salmon to determine the effects of parasitism on selected host immune functions. The humoral antibody response to dinitrophenylated-keyhole limpet hemocyanin and the in vitro blastogenic responses of isolated mononuclear leukocytes to mitogens (concanavalin A, lipopolysaccharide and phytohemagglutinin-P) were evaluated. The humoral response as detected by enzyme-linked immunosorbent assays was suppressed following infection. The degree of suppression increased as the severity of the infection progressed. Additionally, the response to mitogen-induced lymphoproliferation was impaired. These results suggest that infection with E. salmonis may cause suppression of host cell immune functions, thus increasing the susceptibly of infected fish to other pathogens.

Age-associated changes in mitogen-induced lymphoproliferation and lymphokine production in the long-lived brown-norway rat: effect of caloric restriction

We have previously demonstrated that age-related declines in Concanavalin A (ConA), induced proliferation and lymphokine production, occur in ad-libitum fed Brown Norway (AL BN) rats. Since caloric restriction (CR) extends lifespan, we expected that the age related changes in immune parameters would be delayed by CR. CR does act to delay age-related changes in proliferation in response to ConA. In addition, CR postpones the plateau in ConA induced interferon (IFN) production seen after 23 months of age in AL rats. However, CR does not postpone the age-related decline in ConA induced interleukin-2 (IL-2) production. Therefore, ConA induced IFN production maybe a good candidate as an early marker of physiologic aging, while ConA induced proliferative response is a possible candidate for a marker of late stages of aging.

Macrophage-T cell interaction in experimental mycobacterial infection. Selective regulation of co-stimulatory molecules on Mycobacterium-infected macrophages and its implication in the suppression of cell-mediated immune response.

The most important immunopathological consequence of experimental mycobacterial infection is the suppression of T cell-mediated immune response to both mitogens and mycobacterial antigens. We registered that there was decreased concanavalin A-induced spleen cell proliferation in infected susceptible BALB/c mice as compared to normal mice. In resistant (C3H/HeJ) mice, infection with the bacteria did not induce any suppression in the mitogen-induced lymphoproliferation. Likewise, delayed-type hypersensitivity (DTH) responses, to keyhole limpet hemocyanin and mycobacterial crude soluble antigen were suppressed in infected BALB/c mice but not in C3H/HeJ mice. This depressed T helper cell function may either be due to defective T cell-receptor occupancy by antigen-Ia complex or altered co-stimulatory signals provided by antigen-presenting cells. In the present study, we have investigated the status of certain co-stimulatory molecules on the infected macrophages from both susceptible and resistant mice. Our results demonstrate that upon mycobacterial infection, the macrophages are rendered incapable of delivering the co-stimulatory signals to T helper cells, possibly due to the involvement of prostaglandin, as inhibition of its biosynthesis by indomethacin reversed the defect. Furthermore, the selective regulation was bacteria-induced as killing of the bacteria by rifampicin abrogated the derangements in the expression of co-stimulatory molecules on the Mycobacterium-infected macrophages. Our observations revealed that upon infection with Mycobacterium tuberculosis, B7 was down-regulated while ICAM-1 was increased only in BALB/c but not in C3H/HeJ mice. Expression of VCAM-1 did not change during the infection in either strain of mice. We found that these changes in ICAM-1 and B7 expression on the surface of infected macrophages resulted in inhibition of DTH-mediating functions of T helper cells from BALB/c mice. The results obtained in this study describe not only a novel immune evasion strategy adopted by Mycobacterium, but also open up the possibility of immunotherapy of mycobacterial infection by selective manipulation of co-stimulatory molecules.

Inhibition of spontaneous and mitogen-induced lymphocyte proliferation by murine bone marrow-derived macrophages: role of prostaglandins, nitric oxides and cell-to-cell contact.

Spontaneous and mitogen-stimulated proliferation of spleen lymphocytes was inhibited by coculturing the cells with murine bone marrow derived macrophages (BM-M phi). The inhibitory effect was found to be dependent on the maturation stage of BM-M phi reflected by the appearance of the phenotype BM 8 and on the number of BM-M phi added to the lymphocytes. The spontaneous proliferation was only inhibited by the addition of high numbers of BM-M phi of late maturation stage. The lipopolysaccharide (Lps) induced response was strongly suppressed by increasing proportions of BM-M phi of either cultivation stage. The suppressive effect on the concanavalin A (Con A)-induced proliferative activity increased with the maturation of the macrophages. Inhibition of prostanoid release with indomethacin had no effect. Blocking of nitric oxide synthesis partially reversed the inhibitory effect of macrophages mainly on the Con-A response. Addition of culture supernatant of BM-M phi to the lymphocytes did not mimic the effect of the macrophages themselves. BM-M phi only slightly inhibited the proliferation when lymphocyte-BM-M phi cell-to-cell contact was prevented. These results show that BM-M phi differently influence the spontaneous and mitogen-induced lymphoproliferation and that the inhibitory effect of BM-M phi on the lymphocyte proliferation is only partially mediated by secretory products of macrophages but apparently requires cell-to-cell contact between both cell types.

Immune Responses to Bovine Serum Albumin in Chicken Lines Divergently Selected for Antibody Responses to Sheep Red Blood Cells

Primary antibody and cutaneous hypersensitivity responses to BSA revealed differences between two lines of chickens that had been selected during 12 generations for either high (H) or low (L) antibody responses to SRBC. Levels of total and IgM BSA-binding antibodies at Day 8 postsensitization were significantly lower in the L line than in the H line and in a randombred control (C) line that originated from the same parental stock as the selected lines. Both the early and the late classical wing-web responses to BSA were absent in the L line. In contrast, peripheral blood leukocytes from all three lines proliferated equally well in vitro in the presence of BSA. Line by treatment effects were found for mitogen-induced lymphoproliferation in vitro. Peripheral blood leukocytes obtained from BSA-sensitized H line chickens exhibited lower proliferative responses to concanavalin A than peripheral blood leukocytes from C and L line chickens.These results suggest that differences in immune responses in vivo between the present chicken lines are expressed as antibody (-mediated immune) responses to T cell-dependent antigens. The similarity in immune responses to BSA of the H and C lines after 12 generations of divergent selection indicate that selection for an enhanced immune response to one (multiantigenic) antigen (SRBC) may not necessarily implicate improvement of immunity to another antigen (BSA).

Use of staphylococcal enterotoxin A-induced lymphoproliferation and interleukin 2 production as indicators of immunotoxicity.

Suppression of mitogen-induced splenocyte lymphoproliferation and interleukin 2 (IL-2) production can be used as indicators of immunotoxicity. Staphylococcal enterotoxin A (SEA) is both a potent mitogen and the most potent in vitro inducer of IL-2 production that has been described. An in vitro system was used to measure impairment of SEA-induced lymphoproliferation and IL-2 production using splenocytes from female C57BL/6 mice dosed with either cyclosporin A (30 mg/kg/day, 14 days), benzene (220, 440, or 880 mg/kg/day, 14 days), or vehicle. Splenocytes were stimulated with either concanavalin A (con A) or SEA. Benzene- and cyclosporin A-treated mice demonstrated significant decreases in splenocyte proliferation. IL-2 production was determined by incubating splenocyte culture supernatants with IL-2 dependent cytotoxic T-cells (CTLL-2), pulsing with 3H-thymidine, and determining amount of incorporated label. Cell proliferation and IL-2 production were inhibited by both benzene and cyclosporin A, effects more clearly demonstrated using SEA than con A. SEA was a superior mitogen compared to con A in the assays evaluated here.