Patterns of the forming of an immunologic memory to staphylococcal corpuscular antigen

The experiments carried out on inbred mice have revealed that the level of the immunological memory to staphylococci depends on the intensity of the antigenic stimulation; high priming dose of antigen proving to be the most effective one. The opposite character of immune responsiveness observed during primary antibody response to particulate staphylococcal antigen in C3H and A/Sn mice increased after the second immunization. It is established that immunological memory to staphylococci may be induced in genetically athymic mice. Many antibody-forming cells are found in the bone marrow of the secondary immunized mice. This phenomenon may be due to the repopulation of the bone marrow tissue by recirculating memory cells.     

The dynamics of the humoral immune response to mycobacterial antigens in mice]

The main regularities of humoral immune response to mycobacterial antigens have been studied in experiments on BALB/c mice immunized with live and thermoinactivated Mycobacterium tuberculosis, var. bovis. As shown in this study, the maximum level of serum antibodies to mycobacterial antigen is achieved in two weeks after immunization irrespective of the dose and viability or mycobacteria, then follows a decrease in the antibody level. The absence of uniformity in the dependence of primary immune response and the formation of immunological memory on the dose and viability of mycobacteria has been demonstrated.     

Use of Human CD4 Transgenic Mice for Studying Immunogenicity of HIV-1 Envelope Protein gp120

HIV-1 envelope protein, gp120, is a major immunogenic protein of the AIDS virus. A specific feature of this protein is its interaction with the receptor protein, human CD4, an important component of the immune system. This interaction might affect the immunogenic properties of the gp120 and modulate the immune response towards HIV. To test this hypothesis we used human CD4-transgenic mice for immunization with gp120. The dynamics of the immune response towards gp120, CD4 and other proteins was followed. The results show that the primary immune response to gp120 (two weeks) developed somewhat faster in CD4-transgenic mice versus non-transgenic mice. Both animals, however, ultimately mounted the same level of response over time. The primary immune response to gp120 when complexed with soluble CD4 before the immunization, developed similarly in both groups. The secondary immune response was earlier and markedly stronger in non-transgenic mice compared with the transgenic mice where a less efficient memory response to gp120 was observed. The ability of gp120 to directly interact with CD4+ helper lymphocytes appears to affect the humoral response towards this antigen. Moreover, these effects illustrate how viral modulation of these cells may in turn lead to potentially different states of immunological equilibrium.     

Significance of bacteremia in the development of immunological memory suppression in Shigella sonnei infection in mice

Experiments on mice infected intraperitoneally with S. sonnei have revealed that the level of bacteriemia is directly related to the duration of the blocking of immunological memory constituting the basis of secondary humoral and cell-mediated immune response. The transfer of syngeneic splenocytes from immunized mice has demonstrated that virulent S. sonnei directly affect the immunological memory cells.     

Experimental Sepsis Impairs Humoral Memory in Mice

Patients with sepsis are often immune suppressed, and experimental mouse models of sepsis also display this feature. However, acute sepsis in mice is also characterized by a generalized B cell activation and plasma cell differentiation, resulting in a marked increase in serum antibody concentration. Its effects on humoral memory are not clearly defined. We measured the effects of experimental sepsis on long-term immunological memory for a defined antigen: we induced colon ascendens stent peritonitis (CASP) 8 weeks after 2 rounds of immunization with ovalbumin. Four weeks later, the antigen-specific bone marrow plasma cell count had doubled in immunized non-septic animals, but remained unchanged in immunized septic animals. Sepsis also caused a decrease in antigen-specific serum antibody concentration. We conclude that sepsis weakens humoral memory by impeding the antigen-specific plasma cell pool’s development, which is not complete 8 weeks after secondary immunization.     

Primary and secondary immune response of mice to polysaccharide antigens of meningococcal serogroups A and C

The peculiarities of the primary immune response, the formation of immunological memory and the secondary immune response to serogroup A and C meningococcal polysaccharides were studied in 7 strains of inbred mice, hybrids F1 and in noninbred animals. The passive local hemolysis test and the passive hemagglutination test indicated that the intensity of immune response to A and C polysacchardies depended on the genotype of the animals: both antigens induced the most intense response in CBA and BALB/c mice. The primary immune response to the both antigens was characterized by a short latent period, a rapid (by days 4-5) increase in the amount of antibody-producing cells in the spleen and in antibody titer in the blood serum to the maximum level, and a pronounced decrease inantibody formation by days 6-7 followed by a gradual extinction of the response. A single injection of A and C polysaccharides in a dose of 0.5 microgram induced the formation of immunological memory in mice, persisting for at least 4 weeks and manifesting after reimmunization as the increased or more prolonged synthesis of IgM and IgG.     

Immunological memory is compromised by food restriction in deer mice Peromyscus maniculatus

The immune system protects organisms against infection, but this protection presumably comes at a cost. Here, we asked whether food restriction would compromise the ability of an organism to generate an immune response on reexposure to an antigen, which would represent a functional cost of immunological memory. Immunological memory is generated when B and T lymphocytes sensitive to components of pathogens (i.e., antigens) proliferate after exposure and persist in circulation to hinder reinfection. To test the possibility that B cell memory, the component of the immune system responsible for antibody production, is expensive to maintain, secondary antibody production against a novel protein [keyhole limpet hemocyanin (KLH)] was compared in food-restricted and ad libitum-fed male deer mice (Peromyscus maniculatus). To determine whether compromised secondary antibody production was solely due to elevated corticosterone independent of resource availability, some food-restricted and ad libitum-fed mice were subjected to unpredictable, chronic (2 h/day) restraint. Mice fed 70% of their ad libitum diet 2 wk after primary antigen challenge produced approximately 95% less IgG against KLH after a second antigen challenge than mice fed ad libitum, even though all mice were fed ad libitum during the secondary antibody response period. Restraint had no effect on secondary IgG production in response to KLH, and corticosterone concentrations 1 day after food restriction did not differ between food-restricted and ad libitum-fed mice. Together, these data imply that secondary antibody responses and the benefits of immunological memory are energetically costly in this species.     

Effect of Neisseria meningitidis on the humoral response of various strains of mice immunized with ram erythrocytes

The capacity of heat-killed meningococci and the polysaccharide-protein-lipopolysaccharide fraction ( PPLF ) isolated from the microbial cell wall for changing nonspecific immunological reactivity was studied. In this investigation CBA mice with high response and C57BL/6 mice with low response to sheep red blood cells (SRBC) were used. Heat-killed N. meningitidis, serogroup A, and PPLF , serogroups A and B, were found to enhance and suppress humoral response to the heterologous antigen. The effect of modulation depended on the dose of the antigen, the serogroup of meningococci, the scheme of the experiment and the strain of mice. The immune response of the vaccinated animals to the heterologous antigen was characterized by the following stages: the state of the adjuvant effect was replaced by the state of temporary immunodeficiency and then by enhanced response to SRBC.     

Thie expression of an intraspecific aggressive reaction in the face of a stressor agent alters the immune response in rats.

The repercussion on the immune response of the expression of intraspecific aggressiveness in the face of a stressor agent was investigated in rats. Ninety-day-old animals were divided into three groups: the control group (only immunological measurements were performed), the foot-shock (FS) (animals individually receiving FS), and the intraspecific aggressive response (IAR) group (animals receiving FS and presenting IAR). For immunological measurements, blood samples were collected promptly at 7 and 15 days after FS or IAR. The FS reduced the total leukocyte amount presented. However, aggressiveness triggered not only reduction of the leukocytes, but also lymphocyte decrease and neutrophil increase. Moreover, an elevation in total leukocytes associated with an increase in the humoral immune response was also observed one week after IAR. In this study, the expression of intraspecific aggressiveness in the face of a stressor seemed to activate the immune system and to potentiate the antigen specific humoral response.     

Study of the immunotropic activity of aminoglycoside antibiotics

The action of some aminoglycoside antibiotics on the immune system was studied on both intact mice and the animals with immune deficiency caused by administration of cyclophosphamide. The following tests were used: local hemolysis (the Herne test), lymphocyte transformation (LT), delayed hypersensitivity to sheep red blood cells and the local graft versus host reaction (GVHR). Amikacin was shown to have no significant action on the activity of lymphocytes in the intact mice and stimulated both cellular (LT and GVHR) and humoral (the Herne test) immunity in the animals with lowered immunological reactivity. Sisomicin had no significant action on the immune system of the animals. Gentamicin suppressed the immune response only in the intact mice. Kanamycin and streptomycin induced inhibition of humoral and cellular immunity in both the intact mice and animals with immune deficiency. On the basis of the results it was concluded that gentamicin, amikacin and sisomicin may be used in the treatment of diseases developing in the presence of immune deficiency whereas streptomycin and kanamycin should be recommended when inhibition of the immunity is needed.     

TLR7 Recognition Is Dispensable for Influenza Virus A Infection but Important for the Induction of Hemagglutinin-Specific Antibodies in Response to the 2009 Pandemic Split Vaccine in Mice

Recognition of pathogen-associated molecular patterns by pattern recognition receptors of the innate immune system is crucial for the initiation of innate and adaptive responses and for immunological memory. We investigated the role of TLR7 in the induction of adaptive immunity and long-term memory following influenza virus infection and vaccination in C57BL/6 mice. During infection with influenza A/PR8/34 virus, the absence of either TLR7 or MyD88 leads to reduced virus-specific antibodies in the serum and antibody-secreting cells in their secondary lymphoid organs, particularly in bone marrow. In spite of this, the absence of TLR7/MyD88 signaling did not impair the production of protective antibodies. Following immunization with the 2009 pandemic inactivated split vaccine, TLR7(-/-) mice had significantly lower levels of germinal center formation, antibody-secreting cells, and circulating influenza virus-specific antibodies than control animals. Consequently, TLR7(-/-) mice failed to develop protective immunological memory upon challenge. Furthermore, the immunogenicity of the split vaccine was likely due to TLR7 recognition of virion RNA, as its removal from the split vaccine significantly reduced the levels of influenza virus-specific antibodies and compromised the vaccine protective efficacy in mice. Taken together, our data demonstrate that TLR7 plays an important role in vaccine-induced humoral immune responses to influenza virus through the interaction with viral RNA present in the split vaccine.     

Ribonucleic acid in the immune response

Summary In the studies of experimental salmonellosis, immunization of mice with a live vaccine SER of S. enteritidis was found to be effective against further infection with virulent S. enteritidis 116-54. Macrophages obtained from the peritoneal cavity, subcutaneous tissue or liver of immunized mice inhibited intracellular growth of bacteria and resisted cell degeneration caused by engulfment of virulent 116-54 bacteria. This immunity was called cellular immunity.We discovered by chance in 1961 a transfer agent of immunity (TA) from the culture fluid of immunized macrophages. This agent is RNA in nature and can be extracted from the spleen, peritoneal exudate cells or the lymph node of immunized animals and is called immune (i) RNA. We could demonstrate antibody activity in macrophages treated in vitro or in vivo with iRNA by the immune adherence hemagglutination technique.Cellular immunity against tumor cells could be transferred in vitro or in vivo to lymphocytes through iRNA prepared from the spleen cells of syngeneic, allogeneic and xenogeneic animals immunized with the tumor cells.We prepared iRNA against antigens capable of inducing humoral antibody production in animals, i.e., RBCs, bacterial toxin, bacterial flagella and hapten-protein conjugates. Serum antibody was not demonstrated in recipient animals of iRNAs by single or repeated injections of these agents. However, in these animals an increase in the number of specific antibody-carrying cells was found as rosette-formers. It was found further that prior injection of iRNA could induce immunologic memory and produced a high titer of humoral antibody after a boosting stimulation with a small dose of the corresponding antigen. The required interval between the first iRNA and the second antigenic stimulation, and the minimal effective doses of iRNA and antigen are described.We studied the interaction of iRNA with either T- or B-cells and with both cells using adoptive transfer system, athymic nude mice and neonatally thymectomized (NT) mice. Immune RNAs against T-dependent and T-independent antigens could not induce the proliferation of antibody-carrying cells in cyclophosphamide-treated (B-cell depleted) mice. But these agents could induce the proliferation of rosette-formers, implying that iRNAs can replace some role of T-cells even against T-dependent antigens. B-cells can be directly activated by treatment with iRNA against both T-dependent and T-independent antigens, and they differentiated into rosette-formers.Passive transfers of iRNA were successful in establishing immunity against infection with S. enteritidis, or immunity to Salmonella flagella, RBCs and hapten-protein conjugates. The ability of iRNA to confer a secondary response of antibody formation is serially and passively transmissible in recipient animals. These facts suggest the presence of some mechanism that is responsible for the amplification of antigenic stimulation in the immune response. The RNA-dependent RNA polymerase and RNA-dependent DNA polymerase are presented and their role in the immune response is discussed.     

Mechanism of formation of antibody production stimulating ability of bone marrow cells of mice immunized with staphylococci

The mechanism of the increase in immune response to particular staphylococcal antigen was studied in CBA and BALB/c mice injected by primed bone marrow cells (BMC). It was found that immunostimulatory effect of immune BMC is not mediated by macrophages or T cells, but is associated with staphylococcus-specific B memory cells present in the pool of primed BMC. Splenectomy performed in donor animals prior to immunization did not abolish the induction of stimulating BMC activity. It was concluded that primed B lymphocyte migration from spleen into bone marrow is not obligatory for the induction of staphylococcus-specific immunological memory in the bone marrow.     

Mechanisms in immune tolerance. I. A specific block of immunological memory in HSA-tolerant mice

Evidence is provided indicating that the transient immune response detected during the induction of tolerance to HSA in mice, results in immunological memory which persists in an immunosuppressed state in the tolerant animals. The mechanism which blocks this memory is antigen-specific and can be selectively inactivated by total body irradiation in the range of 650–900 R. Consequently tolerant mice, irradiated within this range and restored with normal syngeneic spleen cells, respond better to the tolerizing antigens than do similarly treated normal mice. The tolerizing block can be transmitted from “tolerant” to normal spleen cells when a mixture of both is transferred to normal irradiated recipients. Since similar inhibitory activity is also demonstrated by fresh sera of tolerant mice, it is suggested that the blocking mechanism depends on inhibitory cells which act via a humoral inhibitor.     

Antigen-specific B-cell responses to porcine reproductive and respiratory syndrome virus infection

Porcine reproductive and respiratory syndrome virus (PRRSV) causes an acute, viremic infection of 4 to 6 weeks, followed by a persistent infection lasting for several months. We characterized antibody and B-cell responses to viral proteins in acute and persistent infection to better understand the immunological basis of the prolonged infection. The humoral immune response to PRRSV was robust overall and varied among individual viral proteins, with the important exception of a delayed and relatively weak response to envelope glycoprotein 5 (GP5). Memory B cells were in secondary lymphoid organs, not in bone marrow or Peyer's patches, in contrast to the case for many mammalian species. Potent anti-PRRSV memory responses were elicited to recall antigen in vitro, even though a second infection did not increase the B-cell response in vivo, suggesting that productive reinfection does not occur in vivo. Antibody titers to several viral proteins decline over time, even though abundant antigen is known to be present in lymphoid tissues, possibly indicating ineffective antigen presentation. The appearance of antibodies to GP5 is delayed relative to the resolution of viremia, suggesting that anti-GP5 antibodies are not crucial for resolving viremia. Lastly, viral infection had no immunosuppressive effect on the humoral response to a second, unrelated antigen. Taking these data together, the active effector and memory B-cell responses to PRRSV are robust, and over time the humoral immune response to PRRSV is effective. However, the delayed response against GP5 early in infection may contribute to the prolonged acute infection and the establishment of persistence.     

Role of the T-cell system in glomerulonephritis induced in rats by human serum albumin (HSA)

The primary role of the T-cell system in immune-complex glomerulonephritis induced by intravenous weekly injections of human serum albumin (HSA) in rats has been demonstrated. The development of histological, ultrastructural and immunological glomerular alterations which are clearly recognizable in intact animals was prevented by neonatal thymectomy. In vitro tests of cellular immunity (LIF and PHA responsiveness) revealed a close relationship between the involvement of functioning T-cell subpopulations (at least T-helper) and the development of the classic glomerulonephritic pattern. In other words HSA antigen recognition by T lymphocytes, their cooperation with B lymphocytes, and the activation of the latter with related antibody response represent the immunological sequence which leads to the formation of the soluble circulating immune-complexes responsible for the glomerular injury. Our findings suggest that the same immunological sequence can represent the pathogenetic basis for many forms of glomerulonephritis in which T-dependent antigen stimulation is demonstrable. Our data are also discussed in the light of results obtained by others in immuneglomerulonephritis induced in nude athymic mice.     

Immunologic memory for Staphylococcus studied by adoptive transfer

The basic regularities of the formation and realization of immunological memory to staphylococcal corpuscular antigen were studied in adoptive transfer experiments on CBA mice. The capacity of spleen cells for generating anamnestic response to staphylococci in the body of irradiated syngeneic recipients appeared on day 3 after the immunization of donors. The formation of immunological memory to staphylococci in mice was shown to be directly related to the dose of the antigen. The study also revealed that intact splenocytes did not suppress the realization of immunological memory to staphylococci in the system of adoptive transfer. The conclusion of the absence of the "isogeneic barrier" for memory cells specific to staphylococcal corpuscular antigen was made.     

Adaptive immune defense prevents Bartonella persistence upon trans-placental transmission

Vertical transmission of Bartonella infection has been reported for several mammalian species including mice and humans. Accordingly, it is commonly held that acquired immunological tolerance contributes critically to the high prevalence of Bartonellae in wild-ranging rodent populations. Here we studied an experimental model of Bartonella infection in mice to assess the impact of maternal and newborn immune defense on vertical transmission and bacterial persistence in the offspring, respectively. Congenital infection was frequently observed in B cell-deficient mothers but not in immunocompetent dams, which correlated with a rapid onset of an antibacterial antibody response in infected WT animals. Intriguingly, B cell-deficient offspring with congenital infection exhibited long-term bacteremia whereas B cell-sufficient offspring cleared bacteremia within a few weeks after birth. Clearance of congenital Bartonella infection resulted in immunity against bacterial rechallenge, with the animals mounting Bartonella-neutralizing antibody responses of normal magnitude. These observations reveal a key role for humoral immune defense by the mother and offspring in preventing and eliminating vertical transmission. Moreover, congenital Bartonella infection does not induce humoral immune tolerance but results in anti-bacterial immunity, questioning the contribution of neonatal tolerance to Bartonella prevalence in wild-ranging rodents.     

Selective concurrent suppression of the process of rosette-forming cell accumulation during the immune response]

Repeated injections to mice of normal rabbit immunoglobulins preceding immunization with sheep erythrocytes inhibited the accumulation of rosette-forming cells (RFC) in the spleen, without influencing the proliferation of the antibody-forming cells and hemaggutinin production. Reduction of the RFC under these conditions occurred on account of B-cells whose antigen-binding receptors could be blocked by antibodies against the aggregated mouse immunoglobulins and a complex of polyadenylic-polyuridylic acids. Repeated injections of the competitive antigen enhanced the formation of the immunological memory to the second antigen. The problem of the origin of the immune rosette-forming B-cells and their influence on the formation on the immunological memory is discussed.     

Antigen-initiated B lymphocyte differentiation. V. Electrophoretic separation of different subpopulations of AFC progenitors for unprimed IgM and memory IgG responses to the NIP determinant.

Spleen cells from CBA mice were separated by continuous, free-buffer film cell electrophoresis, and the capacity of cells in different fractions to mount an adoptive immune response specific for the NIP hapten determined. Experimental conditions were such that AFC progenitor B cells were measured, rather than helper or suppressor T cells. The IgM response of unprimed animals (a virgin or antigen inexperienced population) and the IgG response of long-term hapten-primed animals (a B memory cell population) were compared. The results indicated physical and biological heterogeneity in splenic B cells, with AFC progenitors for unprimed IgM and memory IgG responses being extensively separated.AFC progenitors for a primary IgM response in normal, germ-free and athymic mouse spleen, and bone marrow, separated into three distinct populations. Two of these were of much higher mobility than the typical splenic B cells and separated in the T cell zone. These cells produced a relatively early peak response of AFC after stimulation.AFC progenitors for a secondary IgG response were predominantly typical low-mobility B cells. Three regions of activity were separated, one overlapping part of the IgM progenitors. The slowest migrating activity peaks corresponded to the mobility of some recirculating B cells. These cells produced a more delayed AFC response after stimulation.AFC from the spleens of immunised mice separated as a single, broad, mediummobility peak distinct from most B cells and AFC progenitors. IgM and IgG (memory) AFC had similar electrophoretic characteristics.