Frequency of measles virus-specific CD4+ and CD8+ T cells in subjects seronegative or highly seropositive for measles vaccine

The protective effect of measles immunization is due to humoral and cell-mediated immune responses. Little is known about cell-mediated immunity (CMI) to measles vaccine virus, the relative contribution of CD4(+) and CD8(+) T cells to variability in such immune responses, and the immunologic longevity of the CMI after measles vaccination in humans. Our study characterizes cellular immune response in subjects seronegative or highly seropositive for measles vaccine immunoglobulin G-specific antibody, aged 15 to 25 years, previously immunized with two doses of measles-mumps-rubella II vaccine. We evaluated the ability of subjects to respond to measles vaccine virus by measuring measles virus-specific T-cell proliferation. We examined the frequencies of measles virus-specific memory Th1 and Th2 cells by an ELISPOT assay. Our results demonstrated that proliferation of T cells in seronegative subjects was significantly lower than that for highly seropositive subjects (P = 0.003). Gamma interferon (IFN-gamma) secretion predominated over interleukin 4 (IL-4) secretion in response to measles virus in both groups. The median frequency of measles virus-reactive CD8(+) T cells secreting IFN-gamma was 0.09% in seronegative subjects and 0.43% in highly seropositive subjects (P = 0.04). The median frequency of CD4(+) T cells secreting IL-4 in response to measles virus was 0.03% in seronegative subjects and 0.09% in highly seropositive subjects (P = 0.005). These data confirm the presence of measles virus-specific cellular immune responses post-measles vaccine immunization in humans. The detection of measles virus-induced IFN-gamma and IL-4 production by ELISPOT can be used to identify measles virus-specific low-frequency memory T cells in subjects immunized with measles vaccine. These differences agree in directionality with the observed antibody response phenotype.     

Impairment of graft versus host reactivity in pregnant mice.

The popliteal lymph node (PLN) assay for graft versus host (GVH) reactivity has been used to analyse specific features associated with the immunological aspects of the materno-fetal relationship. GVH responses induced following the injection of maternal lymphocytes into F1 hybrid recipients is a particularly relevant model for testing the cellular reactivity of maternal lymphocytes against F1 hybrid determinants since every allogeneic pregnancy could initiate a naturally occurring mother versus F1 allograft reaction. Experiments monitored sequentially the effects of the pregnancy environment and multiparity on maternal cell-mediated immunity. The PLN assay performed within the confines of pregnant F1 hosts indicated that GVH reactivity was significantly suppressed during the mid and late stages of gestation with suppression being greatest in allogeneic combinations. In addition cells obtained from pregnant donors were less efficient than normal cells at GVH induction when transferred to virgin F1 recipients. The suppressive effect was maximal at mid-gestation; however, in this situation, the genotype of the paternal strain had no significant effect on the degree of immunosuppression observed. Multiparity in allogeneic combinations induced anti-paternal humoral immunity but an equivalent increase in GVH reactivity was not detected. These results support the concept of pregnancy-associated suppression of cell-mediated immunity. The nature of the suppressive effect is discussed.     

Effect of a Soluble Factor Secreted From Cultured Human Trophoblast Cells on In Vitro Lymphocyte Reactions

ABSTRACT: The immunoregulatory role of trophoblast cells in cell-mediated immunity was investigated. Trophoblast cells were obtained from 8–10-week human placentae by treatment with collagenase followed by differential centrifugation. The cells were cultured for 48 hr, and the culture supernatant was examined for immunosuppressive activity in vitro. The supernatant when added to cultures of peripheral blood lymphocytes from healthy donors suppressed both their reactivity to different lectins (PHA and PWM) and their activity in one-way mixed lymphocyte reaction. The degree of suppression was dose-dependent. Furthermore, the supernatant was able to reduce the natural killer cell activity against K562 target cells. On the other hand, the supernatant had no inhibitory effect on the effector phase of lymphocyte-mediated cytotoxicity activity against tumor cell lines RPMI 8866 and Daudi. In all cases, the suppression observed was not due to lymphocytotoxicity or tumor cell mortality. The results indicate that trophoblast cells release a soluble suppressive factor that is a potent inhibitor of cell-mediated immunity.     

Blood transfusion-induced suppression of cellular immunity in man

The effect of planned blood transfusions on cell-mediated immunity was studied in previously nontransfused prospective kidney graft recipients. Following transfusion of washed erythrocytes a marked suppression of cellular immunity was found, indicated by reduced response to mitogenic (PHA, Con A, PWM) and antigenic stimulation (Ag-C containing PPD, tetanus toxoid, streptolysin, mumps, vaccinia antigen). A second transfusion led to a more pronounced and prolonged immunosuppression. No suppression was found when autologous blood was applied to volunteers. Preliminary results show autologous and allogeneic MLR suppression when mitomycin-C treated patient cells taken after transfusion are added. Our findings indicate that blood transfusion-induced suppression of cell-mediated immunity might be caused by an unspecific suppressor cell.     

Host Responses to Epstein-Barr Virus and Cytomegalovirus Infection in Leprosy

A study was undertaken in patients with leprosy to assess the contribution of cell-mediated immunity to the host response to Epstein-Barr virus (EBV) and cytomegalovirus (CMV) infection. Sixteen of 72 patients (22%) with lepromatous leprosy, with impaired cellular immunity, had anti-EBV titers of 1,640 or higher. Only 4 of 49 patients (8%) with tuberculoid leprosy, with intact cell-mediated immunity, attained the level of 1:640. The anti-EBV antibody titers were significantly higher in patients with lepromatous leprosy (P approximately 0.025). No significant differences were found in the level of anti-CMV antibody titers in patients with the two types of leprosy. The presence of high anti-EBV antibody titers in lepromatous leprosy suggests that cell-mediated immunity is a significant factor in host response to EBV infection. Host immune responses should be taken into consideration when assignment of an etiological role to EBV is based upon seroepidemiological data.     

Antibody production in mice: III. The suppressive effect of antibody on the initiation of secondary immune response

The suppressive effect of antibody on the secondary immune response was analysed using a technique of memory cell transfer into X-irradiated recipients. The response of memory cells stimulated by antigen-bearing cells was markedly suppressed when antibody was passively administered to recipients and this had its maximal effect when administered simultaneously with the cell transfer. The capacity of memory cells to respond to antigenic stimulation and the capacity of antigen-bearing cells to stimulate memory cells were not directly impaired by the suppressive antibody. The marked suppression was observed only when both memory cells and antigen-bearing cells were present together with antibody. These results suggest that antibody-induced suppression appears to be caused by blocking the effective antigenic stimulus from antigen-bearing cells to memory cells.

Evidence is presented indicating that pre-existing antibody plays a regulatory role in the initiation of the secondary response and also controls the expression of memory.

     

Host Defense Mechanisms Against Infectious Bovine Rhinotracheitis Virus: In Vitro Stimulation of Sensitized Lymphocytes by Virus Antigen

Isolated peripheral blood lymphocytes (PBL) from cattle immunized or infected with infectious bovine rhinotracheitis (IBR) virus were cultured in vitro with ultraviolet light-inactivated IBR virus, and the degree of lymphocyte blastogenesis was quantitated by measurement of the uptake of [(3)H]thymidine into acid-insoluble material. Lymphocyte blastogenesis only occurred with PBL from immunized or infected animals. The optimal conditions for lymphocyte blastogenesis were defined. Blastogenesis was specific since cells from animals immunized against IBR failed to react with two other herpesvirus antigens tested, herpes simplex and equine rhinopneumonitis viruses. Blastogenesis could be prevented by reacting IBR antigen with IBR-specific antibody before adding to cultures, but incorporating IBR-specific antibody in the culture medium after adding free antigen failed to inhibit blastogenesis. With intranasally infected animals, lymphocyte blastogenesis was detectable after 5 days, reached peak levels between days 7 and 10, and then declined to low levels by day 19. In contrast, levels of neutralizing antibody were barely detectable on day 7 and reached maximal concentrations on day 19. The lymphocyte blastogenesis assay was emphasized as a convenient and useful in vitro correlate of cell-mediated immunity that should help define the role of cell-mediated immunity in immunity to herpesviruses.     

Impaired Cellular Immunity to Rubella Virus in Congenital Rubella

Specific cell-mediated immunity (CMI) responses to rubella virus were studied in 12 children with documented congenital rubella syndrome employing a ⁵¹Cr lymphocytotoxicity microassay. Hemagglutination inhibition antibody was detected in 11 of the 12 children, with titers ranging from 1:4 to 1:128. CMI to rubella virus was demonstrated in only 3 of the 11 antibody-positive children. The 12th child was negative for both hemagglutination inhibition and CMI. Of the three children with a positive CMI response, two had histories of reinfection with rubella virus. These data suggest that congenital rubella infection produces an impaired CMI response which subsequently may be altered by reinfection with rubella virus. The lack of CMI in the presence of antibody and concurrent excretion of live virus in the child with documented congenital rubella infection suggest a factor to be explored in the pathogenesis of this disease.     

The role of virus-induced regulatory T cells in immunopathology

In recent years, regulatory T cells have received increased attention for their role in immune responses to microbial infections. The list of microbial pathogens associated with regulatory T cell responses is growing rapidly and includes bacteria, viruses, parasites, and fungi. As the biology of regulatory T cells is revealed, we are discovering that their induction during infection is a normal aspect of immunity, necessary to limit collateral damage from inflammatory responses and aggressive immunological effectors. Thus, these cells play a critical role in maintaining the delicate balance between preventing immunopathology and allowing the immune response to clear infections. While generally successful, there are notable exceptions where regulatory T cell-mediated suppression appears to be responsible for allowing certain viruses to establish and maintain a persistent state. In this review, we will discuss our current understanding of what virus-induced regulatory T cells are, how they are induced, and what mechanisms they use to suppress immunity. The complex role of Tregs in regulating immunity to viral infections, and the consequences their activity has on disease is illustrated by a review of specific viral infections including hepatitis C virus and human immunodeficiency virus.     

Measles Virus-Induced Migration Inhibition of Human Leukocytes In Vitro: An Expression of Cell-Mediated Immunity?

Attempts were made to establish measles virus-induced migration inhibition of human leukocytes as an in vitro test of cell-mediated immunity to the virus. Crude material from cell cultures infected with two different strains of measles virus was used as antigen in the capillary modification of the test. Both virus preparations induced migration inhibition. Incubation with puromycin indicated that the inhibition was dependent on protein synthesis, which has been regarded as a characteristic feature of an immunologically specific inhibition. However, no difference was found when the migration inhibition of leukocytes from donors without clinical and serological evidence of previous measles infection was compared with that of leukocytes from donors with such evidence. It is concluded that the migration inhibition induced by crude measles virus material does not necessarily measure cell-mediated immunity to the virus.     

The introduction of one or two 3 beta-cholestanyl residues into benzylpenicilloyl-eicosa-L-lysines greatly potentiates their tolerogenicity for anti-benzylpenicillol IgE antibody formation

BALB/c mice were repeatedly immunized with microgram doses of benzylpenicilloylated Ascaris protein(s) (BPO9Asc) in alum. At different stages of the immune response, BPO21 eicosa-L-lysine or two analogs containing one or two hydrophobic p-oxymethylbenzyl-3 beta-cholestanyl succinate (OSuco) groups were injected. When injected early in the immune response, the anti-BPO IgE antibody formation was much more strongly and permanently suppressed by the lipophilic conjugates than by the hydrophilic BPO21 eicosa-L-lysine. A similar, but less marked, suppressive effect was observed on the anti-BPO IgG1 response. By adoptive cell transfer experiments, it was found that the OSuco-containing derivatives induce and act via suppressor T lymphocytes, since this cell-mediated suppression was sensitive to cyclophosphamide or to treatment with anti-Lyt-2.2 antibody plus complement. When these compounds were injected into repeatedly immunized mice producing late ongoing antibody responses no differences in suppression between hydrophilic and hydrophobic derivatives were observed. In this case, the IgE response was suppressed by about 50%, while the IgG1 response was not affected. These results are compatible with the suggestion that early IgE responses are most sensitive to T cell-mediated suppression and that T suppressor cells are better induced by lipophilic than by hydrophilic antigens. The late ongoing IgE response, on the other hand, is less amenable to T cell-induced suppression and tolerogenic effects brought about by plurivalent BPO antigens operate directly on hapten-specific IgE-bearing B cells, regardless of their lipophilic character.     

T cell-mediated immunity to oncornavirus-induced tumors III. Specific and nonspecific suppression in tumor-bearing mice

A strong cell-mediated immune response against Friend, Moloney, Rauscher virus-induced (FMR) cell surface antigens has been demonstrated previously in mice which reject oncornavirus-induced tumors. In order to identify an eventual suppressor mechanism in animals with progressively growing tumors, experiments were initiated in C 57 BL/6 mice bearing either a murine sarcoma virus (MSV) tumor or Moloney virus-induced lymphoma (MBL2). Progressive tumor growth was induced (a) in viremic animals first infected with Moloney murine leukemia virus (M.MuLV), then inoculated as adult with MSV; (b) in nonviremic animals injected with MBL2 lymphoma cells. In the absence of tumor cells, viremia induces specific tolerance for which there is no evidence for suppressor cells. In tumor-bearing mice, specific suppressor T cells are detected which are able to inhibit the generation of anti-FMR cytolytic T lymphocytes in vitro and enhance the tumor growth in vivo. In addition to the specific suppressor T cells, a nonspecific suppressive activity mediated by metastatic T lymphoma cells is demonstrated in the spleens of lymphoma-bearing animals. The respective role of the virus and tumor cells in the induction of tolerance to M.MuLV-induced antigens, and their relationship to other components of the specific cell-mediated immune response is discussed.     

Induction of antigen-specific suppression by circulating Cryptococcus neoformans antigen.

Immunoaffinity chromatography of sera from mice infected with Cryptococcus neoformans (Inf-MS) on a column with rabbit anti-cryptococcal antibody as the ligand resulted in the adsorption of the component(s) that induce suppression of the cryptococcal delayed-type hypersensitivity (DTH) response. In contrast, immunoaffinity chromatography of Inf-MS on columns coupled with cryptococcal antigen or goat anti-mouse IgM, IgG, and IgA did not adsorb the suppressive component(s). Quantification of cryptococcal antigen and anti-cryptococcal antibody in Inf-MS and column fractions established a direct correlation between cryptococcal antigen levels and suppressive activity; no correlation was observed between anti-cryptococcal antibody levels and suppressive activity. The suppression induced by Inf-MS was shown to be specific in that suppressive sera did not affect the induction of DTH responses to Listeria monocytogenes or dinitrofluorobenzene. These collective results provide evidence that cryptococcal antigen is the component in Inf-MS that induces antigen-specific suppression of the cell-mediated immune response to C. neoformans.     

Splenic regulation of cell-mediated immunity to Listeria monocytogenes

Splenectomized mice are more resistant than normal mice to infection by Listeria monocytogenes. The nature of splenic regulation of cell mediated immunity to Listeria was investigated. Splenectomized mice were reconstituted with normal syngeneic spleen cells and normal plasma from Listeria-stimulated normal donors to determine if suppression of resistance in normal mice was cellular or humoral. Mice receiving spleen cells showed no decreased resistance, but mice receiving plasma showed decreased resistance as determined from bacterial numbers in the liver. The suppressive effect was associated with plasma components having a molecular weight less than 10,000. The data suggest that a suppressor factor is produced by spleen associated cells in response to stimulation of the cell-mediated immune system.     

Induction of tumor-specific cell-mediated immunity by a noninfectious type-C virus.

Hamsters immunized with either noninfectious hamster type-C virus (D9) or irradiated D9 tumor cells were tested for cell-mediated immune reactivity by the macrophage migration inhibition assay. The migration of peritoneal exudate cells from immunized hamsters was significantly inhibited by either D9 virus or D9 tumor extract, but not by extract of an unrelated CELO virus-induced tumor. The virus and tumor extracts had little or no effect on the migration of peritoneal exudate cells from normal hamsters. Noninfectious D9 virus produces a cell-mediated immune response in the hamster and shares antigenicity with D9 lymphoma, which releases the virus.     

Helper function of CD4 lymphocytes in antiviral immunity in ginbuna crucian carp, Carassius auratus langsdorfii

Although many recent studies have suggested that CD4⁺ helper T cell (Th-cell) functions are well conserved among teleost fishes and mammals, there is little evidence that CD4⁺ Th-cells in fish are actually involved in both humoral and cell-mediated immunity during a secondary immune response. In the present study, adoptive transfer using clonal ginbuna crucian carp and crucian carp hematopoietic necrosis virus (CHNV) was used to investigate the functions of CD4⁺ cells during humoral and cell-mediated immunity. With regard to humoral immunity, transplanting CHNV-sensitized donor cells, containing CD4⁺ cells, into naive fish induced more rapid and stronger antibody production than by transplanting non-sensitized donor cells or sensitized donor cells lacking CD4⁺ cells. During cell-mediated immunity, no significant differences were found in recipients that received sensitized cells regardless of whether the donor cells contained CD4⁺ cells, although recipients that received both sensitized donor cells (with and without CD4⁺ cells) exhibited more efficient cell-mediated cytotoxicity than those that received non-sensitized donor cells. These findings suggest that inducing a secondary antibody response requires CD4⁺ cell help, and secondary cell-mediated immunity can be induced both by CD4⁺ cells and leukocytes other than CD4⁺ cells.     

Suppression of cellular immunity to Listeria monocytogenes by activated macrophages: mediation by prostaglandins.

We previously demonstrated the suppression of cell-mediated immunity to Listeria monocytogenes by Pseudomonas aeruginosa-induced, macrophage-like cells. The present study was undertaken to evaluate the mechanism for this suppression. P. aeruginosa supernatant was shown to activate macrophages by the criteria of increased bactericidal capacities and increased attachment to glass surfaces. Acquired cellular resistance to L. monocytogenes could also be inhibited by macrophages from L. monocytogenes-pretreated mice. The depression of acquired immunity by P. aeruginosa- or L. monocytogenes-activated macrophages did not appear to be due to a reduction of antigenic stimulus after nonspecific macrophage activation. In contrast, our findings suggest that suppression is mediated by activated macrophages through a prostaglandin-dependent mechanism. In vivo administration of aspirin blocked the immunosuppressive effect of P. aeruginosa- or L. monocytogenes-activated cells. Moreover, the suppressive activity of supernatants of macrophages from Listeria-infected mice was reversed when indomethacin was present during supernatant generation. Finally, prostaglandin E1 treatment in vivo profoundly inhibited the induction of cell-mediated immunity to L. monocytogenes. The possible role and mechanism of prostaglandin in suppressing cellular immunity to intracellular bacteria are discussed.     

T lymphocyte function as the principal target of lymphocytic choriomeningitis virus-induced immunosuppression.

Plaque-forming cell responses against sheep erythrocytes, Escherichia coli lipopolysaccharide, pneumococcal polysaccharide, and polyvinylpyrrolidone were examined in mice infected with lymphocytic choriomeningitis virus. A 92 to 96 percent reduction of the thymus-dependent anti-sheep erythrocyte responses was observed 2 to 4 weeks after infection. However, the thymus-independent responses against the three other antigens were close to normal at all stages of the infetion. Studies on allograft immunity of infected C3H mice against DBA/2 mastocytoma cells revealed a severe suppression of the T cell-mediated cytotoxic response which was temporally related to the impaired humoral responsiveness against sheep erythrocytes. The capacity of spleen cells from infected mice to restore immune responsiveness of lethally irradiated recipients against sheep erythrocytes was significantly reduced. The adoptive responses, however, were clearly improved when normal thymus cells were added to the inferior spleen cells. Moreover, it appeared that the spleen cells from immunosuppressed donor mice could not confer suppression to normal lymphoid cells. The presented findings are consistent with the assumption that a numeric deficiency of T cells, or cells belonging to some T cell subpopulation, is the primary cause of lymphocytic choriomeningitis virus-induced immunosuppression.     

Phenolic glycolipid 1 of Mycobacterium leprae causes nonspecific inflammation but has no effect on cell-mediated responses in mice

The involvement of the phenolic glycolipid from Mycobacterium leprae in cell-mediated immunity has been investigated in this study. The phenolic glycolipid itself does not appear to stimulate cell-mediated immunity directly, as shown by its failure to elicit a classical delayed-type hypersensitivity response in mice immunized with M. leprae or to stimulate M. leprae-immune lymph node cells in a lymphoproliferative assay. Intradermal vaccination with the phenolic glycolipid failed to influence the growth of M. leprae in mouse footpads. A nonspecific inflammatory response to the sonicated glycolipid was observed in mice vaccinated with whole M. leprae and in control animals. No evidence was obtained for any adjuvant or suppressive effect on cell-mediated immunity by the phenolic glycolipid either to M. leprae or an unrelated antigen (sheep erythrocytes); neither sensitization nor elicitation to either antigen was affected.     

Pathogenesis of Rinderpest Virus Infection in Rabbits I. Clinical Signs, Immune Response, Histological Changes, and Virus Growth Patterns

Rabbits were intravenously inoculated with an attenuated rinderpest virus (L strain), and general patterns of the disease were investigated. The rabbits developed fever with concomitant occurrence of diarrhea and lymphopenia. Early production of interferon was followed by a rise of neutralizing antibody. Histological examinations revealed an involvement of all of the lymphoid tissues, with primary lesions consisting of necrosis of the lymphoid follicles and formation of giant cells. Immunofluorescent examinations suggested that the virus growth was present in almost all of the lymphoid tissues. The possibility of application of this experimental system for the study of systemic infection by measles virus was discussed.