Differential induction of anti-trinitrophenyl plaque-forming cell responses to lightly and heavily conjugated trinitrophenylated heterologous and autologous erythrocytes in mice

In vivo distribution of particulate antigens and liposomes in murine spleen. A possible role in the humoral immune response

Several particulate antigens and liposomes were intravenously injected in mice in order to study their localization patterns in spleen and liver. Liposomes have been proposed as promising carriers for haptens and antigens. It was studied whether the phospholipid composition, cholesterol content and charge of the liposomes played a role in their distribution within the spleen. Different thymus-independent type 1 and type 2 and thymus-dependent particulate antigens as well as liposomes were labeled with the lipophilic fluorochrome Di-I. After labeling they were intravenously injected and spleens and livers were removed at different time intervals and prepared for light- and fluorescence-microscopy. We have observed that all particulate antigens and liposomes administered to the mice localized according to the same distribution pattern in the spleen. After 2 and 4 h particles were located in macrophages of the marginal zone and after 24 h white pulp macrophages had also ingested particulate antigens and liposomes. So we conclude that the distribution of the particulate antigens and liposomes in the spleen is independent of the immunological nature of the particles. Results are discussed with respect to the question whether or not the distribution of particulate antigens and liposome associated antigens or haptens, may be a crucial factor in determining the type of immune response to be elicited.

Mucosal and systemic antibody formation in the rat after intranasal administration of three different antigens

In order to study the role of nasal-associated lymphoid tissue (NALT) in the local nasal immune response, rats were immunized intra-nasally with either of the following trinitrophenylated (TNP) antigens; the thymus-dependent keyhole limpet haemocyanin (KLH), or the thymus-independent lipopolysaccharide (LPS), or with the particulate (thymus-dependent) sheep red blood cells (SRBC). Primary responses hardly occurred, while only TNP-KLH elicited a considerable secondary response. The major responding organ was the posterior cervical lymph node. Specific antibody-forming cells (AFC) occurred in the medulla and were mainly of the IgA or IgG isotype. Hardly any specific AFC were found in NALT or the surrounding mucosa. Intranasal immunization evoked no antibody response in the lung. Ample anti-TNP antibodies could be detected in the sera of animals, primed and boosted with TNP-KLH or TNP-LPS. No specific serum antibodies occurred after immunization with TNP-SRBC. The results are discussed in view of the immunological defence in the upper respiratory tract.

Elimination of spleen and of lymph node macrophages and its difference in the effect on the immune response to particulate antigens

To study the role of macrophages in the in situ immune response to particulate antigens in spleen and popliteal lymph nodes (PLN), mice were injected with dichloromethylene diphosphonate (Cl2MDP)-containing liposomes to eliminate macrophages, followed by immunization with trinitrophenylated sheep red blood cells (TNP-SRBC). Depletion of macrophages in the spleen caused a strong decrease in the number of antibody-forming cells (AFC), which develop after intravenous (i.v.) injection of the antigen. These results strongly suggested the involvement of splenic macrophages in the processing of TNP-SRBC. In particular, the populations of marginal zone macrophages may be involved in the inductive phase of an antibody response to particulate antigens. These macrophages are strategically positioned at the end of the white pulp capillaries in the marginal zone of the spleen and they have their cell processes between the marginal zone-B cells. Elimination of macrophages in PLN had no effect on the number of AFC, which develop after subcutaneous (s.c.) injection of the antigen in the hind footpads. This indicates that the macrophages are not essential for the induction of a local immune response to the particulate antigen TNP-SRBC. After depletion of lymph node macrophages, the number of AFC developing in the spleen after s.c. footpad injection of the antigen increased and the anti-TNP serum titers were elevated. This may well be caused by the fact that more of the antigen reaches the circulation and subsequently stimulates the spleen.

Studies on active immunization with self antigens. II. Production of antibody related to hapten substitution

BALB/c mice were injected during neonatal life with conjugates in buffered physiological saline, prepared by coupling trinitrophenyl groups (TNP) at various densities to either syngeneic mouse serum albumin (TNP-MSA) or xenogeneic bovine serum albumin (TNP-BSA). Serum samples were obtained on days 30 and 60 after birth, on days 75 and 88 after two booster injections, and monoclonal antibodies were prepared from spleens of neonatally treated mice. The antibody titres, isotypes, and specificities were evaluated by enzyme-immunoassay. It was found that the extent of the anti-TNP immune response to TNP-MSA conjugates depends on the degree of hapten substitution, which is not the case for the anti-TNP-BSA. All the TNP-MSA conjugates induced mainly IgG and only a few IgM antibodies. These antibodies reacted essentially with the TNP group but seemed to have a higher avidity for the TNP-protein conjugate used in their induction. During the course of the immunization, decreasing quantities of TNP-MSA conjugates were needed to inhibit antibody binding. A large amount of monoclonal anti-TNP antibodies was found in hybridomas obtained after neonatal treatment either with TNP-MSA or TNP-BSA. Therefore, it appears that the anti-TNP immune response obtained after antigenic stimulation with sufficiently substituted TNP-MSA conjugates possesses all the characteristics of a normally occurring humoral immune response.

Alveolar macrophage elimination in vivo is associated with an increase in pulmonary immune response in mice

A single intracheal dose of liposome-encapsuled dichloro-methylene-diphosphonate resulted in the elimination of alveolar macrophages (AM) from the lung, creating a model to study the in vivo role of AM in the pulmonary immune response. Using intratracheally administered trinitrophenyl-keyhole limpet hemocyanin (TNP-KLH), the kinetics of the response, the location and number of TNP-specific antibody-forming cells, and the different Ig classes of the antibodies produced were studied in AM-depleted animals. The results show that AM elimination has a dramatic effect on the pulmonary immune responses against TNP-KLH. An increase in APC in lung-associated lymph nodes and a prolongation of the response is found, as well as an introduction of APC in lung tissue. In both experimental groups, the majority of the TNP-specific antibodies produced was IgG, followed by IgA and IgE, while very few IgM antibodies could be detected. We conclude from these results that AM are likely to play a role in controlling the pulmonary immune response in a suppressive way, thereby limiting the possible damage caused by severe immune responses in lung tissue.

Marginal zone macrophages and their role in the immune response against T-independent type 2 antigens: modulation of the cells with specific antibody

Marginal zone macrophages are strategically positioned in the marginal zone of the spleen and are thought to play an important role in the initiation of the immune response to T-independent type 2 responses. The cells are characterized by high phagocytic activity and by the selective uptake of neutral polysaccharides. In the mouse marginal zone macrophages react specifically with the monoclonal antibody ER-TR9. Injection of the antibody resulted in a complete abrogation of the uptake of neutral polysaccharides by the cells in vivo, although the cells were still capable of taking up latex and carbon particles. The complete blockade of the polysaccharide uptake did not result in an altered humoral immune response against this antigen. When the antibody ER-TR9 was coupled to the toxin gelonin a complete elimination of the marginal zone macrophages could be established in vivo. However, complete elimination did not result in changes of the immune responses against 2,4,6-trinitrophenylated Ficoll, suggesting that the marginal zone macrophages are either not involved in this type of response, or that their function can be taken over by other cells. The possible role of these cells and the importance of the spleen in the immune response against bacterial antigens is discussed.

Interacting genetic factors controlling the antibody response against the H-2.2 specificity

The antibody response against the H-2.2 specificity has been studied in three H-2d strains. B10.D2. DBA/2. and BALB/c. and their hybrids (B10.D2 x DBA/2)F1 and (B10.D2 x BALB/c)F1. The genetic control of the response appears to be complex: The three pure strains are responders, whereas both hybrids when immunized with C3H-HTG are nonresponders. Individual analysis of N3 offspring is compatible with the idea that, in this combination, an Ea-4 incompatibility between donor and immunized strain is necessary for the anti-H-2.2 response to occur. H-2d/H-2k hybrids (B10.BR x B10.D2)F1 or (B10.BR x DBA/2)F1 are responders when immunized with C57BL/10 (H-2b) but not with B10.A(2R) (H-2h), indicating that simultaneously recognized H-2 specificities are necessary for the anti-H-2.2 response.

Suppression of the immune response to altered self induced by immunogenic and nonimmunogenic altered self structures

Fluorescein (FITC)-haptenated mouse spleen cells are capable of inducing a B cell immune response characterized by the production of antibodies directed against hapten-altered self structures. The induction of this response is thymus-independent and strictly dependent on the hapten concentration used for labeling the cells. Pretreatment of mice with immunogenic, labeled spleen cells strongly suppressed the plaque-forming cell response to a subsequent challenge with FITC-labeled spleen cells, sheep (SRC) or horse (HRC) red cells labeled with the same hapten and native FITC-dextran. Mice primed with lightly haptenated (nonimmunogenic) cells 7 days before challenge were completely unresponsive to the immunogenic dose of labeled cells and displayed a significantly reduced response to FITC-SRC or FITC-HRC. However, the response to FITC-dextran was enhanced, as compared to unprimed animals. The concept of immunogenic vs. nonimmunogenic requirements of an antigen to induce unresponsiveness, and the specificity of the B cell clones affected by suppression is discussed.

Genetic regulation of the antibody response to H-2Db alloantigens in mice. III. Inhibition of the IgG Response to noncongenic cells by preimmunization with congenic cells

When B10.A (5R) mice (H-12i5) are immunized with spleen cells from congenic B10 mice (H-12b), they respond to alloantigens of the H-2Db region by producing antibodies of only IgM type. In contrast, they produce both IgM and IgG antibodies when immunized with A.BY cells (H-2b) that carry other foreign cell surface antigens (non-H-2) in addition to H-2Db. Preimmunization of 5R mice with two injections of congenic cells leads to an H-2Db specific inhibition of the IgG response to a subsequent immunization with A.BY cells. It is concluded that congenic B10 cells fail to activate helper T cells which are necessary to induce the switch from IgM to IgG production. Instead T- or B-cell tolerance may be induced with prohibits the subsequent IgG response to A.BY cells, possibly by way of suppressor T cells which may act either on B cells directly or via helper T cells.

Genetic regulation of the antibody response to H-2Db alloantigens in mice. II. Tolerance to non-H-2 determinants abolishes the antibody response to H-2Db in B10.A(5R) mice

B10.A(5R) mice (H-2i5), immunized with spleen cells from congenic B10 mice (H-2b), responded to alloantigens of the H-2Db region by producing antibodies of only IgM type. In contrast, they produced both IgM and IgG antibodies when immunized with noncongenic H-2b cells that carry other foreign cell surface antigens (non-H-2) in addition to H-2Db. A hypothesis was proposed comparing the H-2Db antigen on a congenic cell to a hapten on a nonimmunogenic carrier which fails to induce T-cell helper function responsible for the switch from IgM to IgG secretion in B cells. Data presented here confirmed this hypothesis. 5R mice rendered tolerant to the relevant non-H-2 antigens were unable to mount the anti-H-2Db IgG response in a noncongenic immunization. Tolerance induction did not lead to abrogation of the T-cell mediated cytotoxicity.

Clonal dominance. I. Restricted nature of the IgM antibody response to group A streptococcal carbohydrate in mice

The IgM antibody response of mice to the streptococcal group A carbohydrate (GAC) was measured. With most strains tested, large amounts of IgM antibody were produced; in AKR mice, over 1% of the total nucleated spleen cells secreted IgM anti-GAC antibody after hyperimmunization. The relative avidity of the antibody was extimated by a modification of the Jerne plaque assay where spleen cells from individual mice were tested against erythrocytes with varying GAC epitope densitymthese studies showed that the earliest, as well as latest, IgM antibodies produced were highly restricted in avidity heterogeneity. No evidence of affinity maturation was seen upon hyperimmunization. These data favor the conclusion that the restricted IgG response seen in mice hyperimmunized to GAC is not the result of affinity driven competition for antigen among precursor cells.

Lack of requirement for thymocytes for efficient antibody formation to trinitrophenylated mouse red cells in mice: role for thymocytes in suppression of the immune response

The requirement of thymus-derived cells for the immune response to trinitrophenylated syngeneic mouse red cells (TNP-MRC) was investigated. In three sets of experiments the following results were obtained: a) irradiated mice which were reconstituted with bone marrow cells alone showed a better anti-TNP response after injection with TNP-MRC than those reconstituted with both bone marrow cells and thymocytes. b) Anti-thymocyte serum augmented the mouse anti-TNP response to TNP-MRC. c) Nude thymusless mice showed a better anti-TNP response to TNP-MRC than their normal littermate controls. These results indicate that the anti-TNP response of mice to TNP-MRC does not require thymus-derived helper cells. Moreover, thymus-derived cells have a suppressive effect on the anti-TNP response.

Genetic regulation of the antibody response to H-2Db alloantigens in mice. I. Differences in activation of helper T cells in C57BL/10 and BALB/c congenic strains

B10.A(5R) mice immunized with C57BL/10 spleen cells demonstrate a normal T-cell-mediated cytotoxicity to H-2Db tumor cells but they do not mount any IgG antibody response to H-2Db alloantigens. B10.A(5R) mice do show a high titered IgG response when immunized with A.BY cells, which differ at H-2Db plus non-H-2 cell surface antigens, or with B10.A(2R) cells, which differ at H-2Db, H-2Kk, and H-2Ik cell surface antigens. These findings indicate a failure of the T-helper cells to induce the switch from IgM to IgG when the H-2Db alloantigens are the only difference on the immunizing cell. In immunizing H-2d mice with congenic H-g2 cells which differ only in the H-2Db region, mice of the C57BL/10 background made only IgM antibodies whereas mice of the BALB/c background made IgG antibodies. This comparison confirms that genes separate from H-2 regulate the T-cell helper function. The genes that influence the T-cell helper function do not regulate the T-cell-mediated cytotoxicity.