Antibody formation. II. The specific anamnestic antibody response

Regulation of the immune response. I. Differential effect of passively administered antibody on the thymus-derived and bone marrow-derived lymphocytes

The effect of passively transfered antiserum against sheep erythrocytes (SRBC) on the antigen stimulated increase of SRBC-specific plaque-forming cells (anti-SRBC-PFC) and SRBC-specific thymus-derived lymphocytes (SRBC-specific T-cells) in the mouse spleen was examined. A dose of antiserum which severely suppressed the development of anti-SRBC-PFC did not prevent the increase in SRBC-specific T-cells, as measured by their ability to cooperate in the in vitro response to trinitrophenylated (TNP) SRBC. It was shown that the insensitivity of these T-cells to antiserum could not be explained by their low antigen requirement as compared to that of PFC. In the in vivo response of mice to TNP-SRBC, antibody specific for TNP suppressed the appearance of both anti-TNP- and anti-SRBC-PFC. The presence of free SRBC specifically prevented the suppression of the anti-SRBC-PFC. These observations are consistent with opsonization by phagocytic cells as the primary means of the observed suppression of PFC development by antibody.

Antibody formation. I. The suppression of antibody formation by passively administered antibody

The suppression of antibody formation by passively administered antibody is influenced by the dose and nature of the antigen, type of immunization procedure, ratio of antibody to antigen, species origin and characteristics of the antiserum used, as well as the species selected for immunization. In guinea pigs, diphtheria antitoxin formation can be effectively suppressed by an intravenous injection of excess homologous or heterologous antitoxin as long as 5 days after toxoid immunization and after delayed-type hypersensitivity to toxoid has developed. Following the period of antibody suppression which lasts 2 to 7 weeks, serum antibody can usually be demonstrated. It is proposed that this delayed immunization results from dissociation of antigen, since diphtheritic paralysis and death can be produced in guinea pigs and rabbits by the intravenous injection of toxin-antitoxin precipitates formed in antitoxin excess. This syndrome is prevented by injection of excess horse antitoxin 1 hour after injection of the toxin-antitoxin complexes.

Antibody formation. III. The primary and secondary antibody response to bacteriophage phi X 174 in guinea pigs

Injection of a small bacteriophage φX 174 into guinea pigs results in an accelerated elimination of phage detectable as early as 24 hours after injection. The immune nature of the accelerated elimination is indicated by its specificity, by the appearance of excess specific serum antibody after phage elimination, and by the prevention of accelerated elimination by 400 r whole body x-irradiation of guinea pigs prior to injection of phage. The early antibody response is considered to be a primary one since an analogous response occurs in newborn guinea pigs, antibody is not detectable in the sera of non-immunized animals, and the second challenge with φX stimulates a serum antibody response 100-fold greater than that after primary immunization. The early detection of immune elimination appears to be due, in part, to the small amounts of phage employed, since larger doses of phage delay the time of onset of detectable immune elimination. The early rise of serum antibody in the primary and secondary response appears exponential with a similar rate constant of antibody formation. The rate constant is also independent of dose. These findings have led to the suggestion that during this exponential phase, the relative rate of antibody formation at a cellular level may be constant for a given antigen.

Antibody feedback and somatic mutation in B cells: regulation of mutation by immune complexes with IgG antibody

In response to an appropriate antigenic stimulus, and with help from T lymphocytes, naive B cells differentiate into plasmacytes which produce the primary (germline-encoded) IgM and IgG antibody with low affinity for the antigen. The isotype switch from IgM to IgG coincides with the burst of germinal center reaction and the onset of somatic hypermutation. Here we propose that formation of immune complexes between the residual antigen and the primary IgG antibody, which activate complement and localize specifically in the network of follicular dendritic cells, provides an important signal for triggering the mutation mechanism in germinal center B cells. This hypothesis has been supported by studies on immunogenicity of immune complexes in vivo. The experiments have included an immunization with pre-formed antigen/IgG antibody complex and/or an administration of IgG antibody shortly after the antigen injection. Either of these strategies, which are known to augment the germinal center formation, resulted in earlier onset of somatic mutation and increased mutation frequency in VDJ rearrangements in antigen-reactive B cells, provided that help from T cells was also present. It is presumed that the antigen/antibody/complement complex is able to deliver this important signal by cross-linking of antigen receptor with the CD21/CD19/CD81 molecules on B cells. As a corollary, the signaling by immune complexes may lower the threshold of cell activation determined by receptor affinity for antigen and stimulate diverse V-gene repertoire of B-cell clones in germinal centers.

IMMUNOGLOBULIN ISOANTIGENS (ALLOTYPES) IN THE MOUSE. I. GENETICS AND CROSS-REACTIONS OF THE 7S GAMMA-2A-ISOANTIGENS CONTROLLED BY ALLELES AT THE IG-1 LOCUS

Eight antigens of 7S γ₂-immunoglobulins controlled by alleles at a single locus Ig-1, have been identified in mice. This locus has previously been shown to determine antigenic specificities on the F fragments of 7S γ_2a-globulins. The reactions of these antigens with various isoantisera have shown that the antigens all cross react with one another. New methods for the analysis of antigenic specificities of soluble proteins are presented in detail. A sensitive method for detecting in the order of 0.01 µg of these isoantigens has been developed, based on the quantitative inhibition of precipitation of I¹²⁵-labeled antigen. Cross-reactions of the antigens were analysed in inhibition assays and the data is compatible with the existence of a minimum of eight antigenic specificities. Each of the antigens is composed of different combinations of these specificities, with only one antigen having a specificity not present in any other. Sixty-eight mouse strains have been tested with specific isoantisera, and on the basis of the results, have been placed into the eight allele groups. Evidence for close genetic linkage of the Ig-1 locus and 11 chromosome markers has been sought and not found.

IMMUNOLOGIC TOLERANCE AFTER SPECIFIC IMMUNIZATION

Specific immunologic tolerance to bovine serum albumin (BSA) was induced in approximately one-half of the rabbits that had been primarily immunized and were prepared for a secondary antibody response to BSA. The state of tolerance lasted for several months in the majority of rabbits and was not easily terminated by immunization with human serum albumin followed by BSA.

Specific IgM enhances and IgG inhibits the induction of immunological memory in mice

The effect of priming mice with IgM anti-SRBC (sheep erythrocytes) together with SRBC or IgG anti-SRBC together with SRBC on the development and expression of memory cells was studied. Mice primed with specific IgM and SRBC showed a much more efficient secondary plaque-forming cell and serum antibody response after challenge with SRBC in an adoptive transfer system than did controls primed with SRBC only. The expression of this enhanced memory of IgM-primed spleen cells was counteracted by the high levels of internal IgG anti-SRBC (also the result of priming with IgM) when the mice, instead of being tested in adoptive transfers, were challenged directly. The antigen-specific feedback suppression of the primary antibody response by specific IgG antibodies was also seen to inhibit partially the development of memory cells. The suppressive effect on priming could be demonstrated both in adoptive transfer systems and after direct boost of the same mice that received the primary immunization. Both the IgM enhancement and the IgG suppression of memory cell development were antigen-specific, since no effect on the antibody response to a non-cross-reacting antigen, horse erythrocytes, was seen. The effect of these up- or down-regulations of immunological memory could be demonstrated after secondary injections as long as 90-280 days after priming.

Effect of maternal antibody upon vaccination with infectious bovine rhinotracheitis and bovine virus diarrhea vaccines

This report presents the normal rate of decay of maternal antibody and the influence of maternal antibody on responses to a single vaccination with modified-live bovine virus diarrhea and infectious bovine rhinotracheitis virus vaccines at 196 days of age and on response to vaccinations with the same vaccines given twice at 84 and 196 days of age. Passive immunity decreased to near zero over the first six months of life for both bovine virus diarrhea and infectious bovine rhinotracheitis controls. All calves seroconverted to bovine virus diarrhea vaccine at 84 days of age, even though high levels (greater than 1:32) of maternal antibodies were present. These calves did not seroconvert to infectious bovine rhinotracheitis vaccine at 84 days of age when high levels (less than 1:16) of maternal antibodies were present. Calves responded well to bovine virus diarrhea and infectious bovine rhinotracheitis vaccines given only once at 196 days of age after passive immunity disappeared. Calves which were revaccinated with infectious bovine rhinotracheitis seroconverted showing a more rapid response than the single vaccinates. Those revaccinated with bovine virus diarrhea showed an immediate response of small magnitude.

Immunoregulatory circuits which modulate responsiveness to suppressor cell signals: characterization of an effector cell in the contrasuppressor circuit

Spleen cells from neonatal animals, placed in culture for 6 days spontaneously develop the ability to block the activity of suppressor T cells, a phenomenon that is referred to as contrasuppression. The effector cell which is derived from the interactions among the cells which comprise a contrasuppressor "circuit" is an Ly-1 T cell. It can be separated from Ly-1 helper cells by three criteria other than function: its generation is dependent on Ly-2+ cells, it is I-J+, and it sticks to the Vicia villosa lectin. Those cells which deliver help to B cells under the experimental conditions studied are not dependent on Ly-2+ cells for generation and neither express determinants that our anti-I-J antisera recognize nor stick to V. villosa. The mechanism by which these Ly-1 contrasuppressor cells function was elucidated by adding them to "'intermediate cultures" containing activated Ly-2 suppressor cells and in vivo immunized Ly-1.1-congenic helper cells. After 48 h in these intermediate cultures, the neonatal Ly-1.2 contrasuppressor cells and the Ly-2 suppressor cells were removed by treatment with the appropriate antiserum plus complement. The remaining activity of the in vivo generated Ly-1.1 helper cells was assayed in fresh cultures of B cells. The contrasuppressor cells not only diminished suppression of the Ly-1 helper cells by the Ly-2 suppressor cells in the intermediate culture, but actually conferred a state of relative resistance to suppression upon the helper cells. This state persisted after the contrasuppressor cells were removed. Why such a cellular circuit, which confers resistance to suppression, might be beneficial to neonatal mice and how considering its attributes might help explain some immunological paradoxes is the subject of discussion.

The interaction of particulate horseradish peroxidase (HRP)-anti HRP immune complexes with mouse peritoneal macrophages in vitro

The uptake, distribution, and fate of particulate horseradish peroxidase (HRP)-anti HRP aggregates has been studied in homogeneous monolayers of mouse macrophages in vitro. Macrophages rapidly interiorize the immune complexes after binding to the cell surface. The rate of interiorization is maximal for complexes formed in a broad zone of 4-fold antibody excess to equivalence and corresponds to a rate of 10% of the administered load/10(6) cells per hour. This rate is 4000-fold greater than the uptake of soluble HRP. The binding and endocytosis of HRP-anti HRP by macrophages is mediated by the trypsin insensitive F(c) receptor. Cytochemically, intracellular HRP is localized within membrane bound vacuoles. After uptake of HRP, the enzymatic activity is degraded exponentially with a half-life of 14-18 hr until enzyme is no longer detectable. This half-life is twice as long as that previously observed for soluble uncomplexed HRP and is related to the combination of HRP with anti-HRP rather than the absolute amounts of enzyme or antibody ingested. The half-life of HRP-(125)I was 30 hr. Exocytosis of cell associated enzyme or TCA precipitable counts was not detected, nor were persistent surface complexes demonstrable. The extensive capacity of macrophages to interiorize and destroy large amounts of antigen after the formation of antibody illustrates a role of this cell in the efferent limb of the immune response.

Antigen-antibody complexes in the immune response. I. Analysis of the effectiveness of complexes on the primary antibody response

Soluble crystalline bacterial α-amylase (BαA)-mouse anti-BαA antibody complexes (Ag—Ab complexes) elicited a primary antibody response in mice with a single intravenous injection, while free BαA could not. The response was dose dependent. Ag—Ab complexes were not only phagocytosed but also degraded more rapidly than free BαA in vivo and in vitro but these characteristics themselves were not important for immunogencity of the complexes.

The Ag—Ab complexes phagocytosed by cells in normal spleen and lymph node elicited a primary antibody response when injected into non-irradiated mice but the response was suppressed when anti-BαA antibody was simultaneously injected. On the other hand, free BαA phagocytosed by cells could not elicit the response.

The degraded products of complexes phagocytosed by normal spleen and lymph node cells were highly immunogenic and probably retain antigenic fragments. They elicited an even higher primary antibody response than the original complexes and were also more effective in eliciting a secondary response from primed cells than the original complexes or free BαA. The degraded products of free BαA, however, were ineffective not only for the primary response but also for primed cells.

Ag—Ab complexes prepared with heterologous rabbit antibody were ineffective for the primary antibody response.

Suppression of the immune response

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Antibody-mediated suppression of the immune response in vitro. I. Evidence for a central effect

Antibody-mediated suppression of the in vitro immune response to polymerized flagellin of Salmonella adelaide and to sheep erythrocytes was studied at the cellular level. Normal mouse spleen cells, preincubated in vitro with mixtures of antigen and antibody for short periods of time before being washed, did not respond to an optimal antigenic challenge in vitro, whereas similar cells treated with antibody alone gave a normal response. The degree of immune suppression was found to depend on the time of preincubation. Significant immune suppression could be induced in as short a time as 15 min, whereas profound suppression (90%) required the incubation of cells with mixtures of antigen and antibody for 4-6 hr. Mouse spleen cells treated similarly were also unable to respond subsequently to the antigen upon transfer to lethally irradiated hosts, as measured at both the level of the antigen-reactive cell and that of serum antibody production. These results were taken as evidence that in vitro an effect of antibody-mediated suppression occurred at the level of the immunocompetent cell. Similarities between immune tolerance and antibody-mediated suppression in vitro were described, and the significance of the findings discussed in the light of current concepts of the mechanism of antibody-mediated suppression.

Localization of 125-I-labelled antigen in germinal centres of mouse spleen: effects of competitive injection of specific or non-cross-reacting antigen

Studies were performed on localization of ¹²⁵I-human γ-globulin in spleen lymphatic tissue germinal centres during the primary and secondary immune response as influenced by competitive injections of specific or non-cross-reacting antigens. Isologous mouse 7S serum protein labelled with ¹²⁵I was used as the control. The results of these studies support the following conclusions:

(1) Antigen retention in germinal centres during the primary immune reaction is a dynamic process. For some antigens there may be opsonins available at the the time of injection which promote initial localization in germinal centres. However, the continued localization of antigen over weeks and months is a function of specific antibody production.

(2) For some period of time, germinal centres are specific to the antigen that stimulated their development, and eventually these centres will respond to a different antigen.

(3) Antigen persisting in germinal centres is functional in the development of the secondary immune potential.

Viral oncolysis: increased immunogenicity of host cell antigen associated with influenza virus

A2G mice could be solidly immunized against the Ehrlich ascites tumor by single intraperitoneal injections of homogenized and lyophilized tumor cells which had been infected with oncolytic strains of influenza A virus. Similar homogenates from noninfected tumor cells were not immunogenic, even when mixed with egg-grown virus. The immunizing principle in viral oncolysates could not be separated from the oncolytic virus by differential centrifugation or adsorption to and elution from red cells. It could be inhibited by antibody raised in rabbits against the egg-grown oncolytic virus. This reaction showed serologic specificity. Thus, the immunogenicity of an oncolysate produced with the WSA strain of neurotropic influenza virus could be inhibited by rabbit anti-WSA, but not by rabbit antibody to the TUR strain of fowl plague virus. Conversely, the immunogenicity of an oncolysate prepared with the TUR strain could be inhibited by rabbit anti-TUR, but not by anti-WSA. When mice were preimmunized (primed) with egg-grown WSA virus, their antitumor response to a later injection of WSA oncolysate was of the anamnestic type. Priming with egg-grown influenza B virus had no such effect. It was concluded that the immunogenicity of certain host cell components was greatly increased by incorporation into the makeup of the oncolytic virus.

The influence of antibodies on immunologic responses. I. The effect on the response to particulate antigen in the rabbit

The influence of antibody on antibody formation to particulate antigen was examined in the rabbit with special reference to the importance of immunoglobulin type, the amount and relative proportion of antigen and antibody involved, and the specificity of this influence. 19S as well as 7S antibody was shown to be an effective inhibitor of antibody formation, although there was some evidence that 7S antibody was the more efficient of the two in doing so. The inhibitory effect of antibody was found to be specific for homologous antigenic determinants. Both 19S and 7S antibody were also able to enhance antibody formation. In contrast to the suppressive phenomenon, however, enhancement appeared to be nonspecific since antibody reactive with homologous (sheep red blood cell) determinants could enhance the response not only to homologous determinants but to heterologous (dinitrobenzene) determinants conjugated to the red blood cells as well. Smaller amounts of antibody were needed to enhance than to suppress antibody formation, and suppression and enhancement depended to some extent on the amount of antigen as well as to the amount of antibody used. The enhancing and suppressing influence of antibody on antibody formation appeared to be exerted concomitantly, for the response to some antigenic determinants was sometimes suppressed at the same time that the response to others was enhanced. It is suggested that enhancement or suppression of immunologic responses by antibody represents a different balance of at least two competing factors operating together: specific neutralization of appropriate determinants thus decreasing the total effective concentration of these determinants available to stimulate the formation of antibodies, and a nonspecific increase in the availability of antigen to immunologically competent cells.

The effect of passively administered antibody on antibody synthesis

Suppression of the primary response of rabbits to intravenously administered KLH can be achieved with very small amounts of hyperimmune anti-KLH administered a day later since the rabbit apparently rapidly eliminates most of the KLH by nonimmunologic means. The amount of passive anti-KLH needed to achieve immunosuppression was directly proportional to the dose of injected antigen. Antibody passively administered as much as 6-8 days after antigen still can be strongly immunosuppressive, which suggests that the antibody must be reacting with immunogen in or on responding cells or perhaps in the process of transfer between cells. There was no evidence that the presence of passively administered hyperimmune anti-KLH prior to the injection of antigen had any immunosuppressive action beyond the direct neutralization of the injected antigen. When KLH was injected in Freund adjuvant, anti-KLH incorporated with the KLH in the adjuvant was much more efficient in causing immunosuppression than anti-KLH given intravenously. The primary responses to 2 mg KLH given intravenously and 2 microg given in adjuvant reached approximately equal peaks and were suppressible by comparable amounts of intravenously administered anti-KLH. Two observations suggest that passive antibody neutralizes the immunogenic stimulus at the level of individual antigenic determinants and not merely by aggregating or precipitating entire antigenic molecules. First, anti-abalone hemocyanin (AH) which cross-reacts approximately 50% with KLH was only partially immunosuppressive even in extremely large amounts, i.e., amounts which could react with and precipitate much more KLH than could the smaller but more suppressive doses of anti-KLH. Second, when KLH and anti-KLH were given together in adjuvant, effective immunosuppression was achieved only with amounts of anti-KLH sufficient to saturate or cover virtually all available antigenic determinants. The immunosuppressive quality of passive antibody increases with time after immunization and with repeated immunization of the donor. In view of their relatively weak immunosuppressive properties, antibodies formed in the first weeks of a primary response may not contribute significantly to the turning off of the antibody response. In any event, results obtained by passive transfer of hyperimmune antibody to animals early in a primary response cannot be applied to the natural events in a primary response.

Factors influencing the immune response. II. Effects of the physical state of the antigen and of lymphoreticular cell proliferation on the response to intraperitoneal injection of bovine serum albumin in rabbits

The injection of Corynebacterium parvum at the same time as centrifuged bovine albumin has been shown not to have the adjuvant effect found when C. parvum is injected 6 days before. The implication of this is discussed and related to mechanisms of antibody synthesis.

Whereas particulate alum-precipitated centrifuged bovine albumin was shown to be more effective than centrifuged bovine albumin in inducing primary antibody stimulation, the reverse was true for secondary stimulation by the intraperitoneal route.

Antibody synthesis at the cellular level. Antibody-induced suppression of 7S antibody synthesis

The specific suppressing activity of passively administered antibody on 7S antibody synthesis against sheep and chicken red blood cells has been investigated at the cellular level using the indirect hemolytic agar-plaque technique. 7S antibody production was found to be sensitive to antibody-induced suppression. No inhibitory effect of transferred antibody was seen until 48 to 72 hr after administration. This indicates that the action of antibody is not by direct suppression of synthesis of already committed cells but rather by removal from the system of the stimulus for maintenance of 7S synthesis. The sensitivity of the 7S system to inhibition decreases with time after immunization but significant specific suppression could still be obtained if transfer of antibody was delayed until 40 days after immunization. The present findings emphasize the role of antibody as a feedback factor during a substantial postpeak period of 7S antibody synthesis and suggest an important role of antigen in stabilizing the 7S antibody production.

Rh Factor: Prevention of Isoimmunization and Clinical Trial on Mothers

The results on the use of gammaG-immunoglobulin to Rh factor for the prevention of active immunization of Rh-negative mothers at risk appear most promising. One hundred and seven mothers in the clinical trial have been followed for periods of about 6 months to 1(1/2)12 years after delivery. Of these, 48 were treated mothers who received 5 ml gammaG-immunoglobulin to Rh, and 59 were untreated mothers. Of the 48 treated mothers none are actively immunized; seven of the 59 control mothers have become actively immunized to Rh.

Specific Inhibition of Antibody Formation by Passively Administered 19S and 7S Antibody

Intravenously administered 7S antibody is more effective than 19S antibody in inhibiting the formation of antibody to bacteriophage X174. Since considerable amounts of 7S antibody are needed for inhibition, serum antibody formation may act as a "feedback" mechanism to prevent hyperimmunization.