Studies of immune responses in mice prone to autoimmune disorders. II. Decreased down-regulation by auto-anti-idiotype antibody in autoimmune-prone mice

Three lines of evidence are presented which suggest that autoimmune-prone mice are deficient in the production of auto-anti-idiotype antibody during their immune response to trinitrophenylated Ficoll (TNP-F). NZB, MRL lpr/lpr and older BXSB male mice have no hapten-augmentable plaque-forming cells (PFC). Hapten-augmentable PFC have been previously shown to be cells whose secretion of antibody has been inhibited by the binding of auto-anti-idiotype antibody to cell surface idiotype. Sera from TNP-F immunized NZB mice lack PFC inhibiting activity (anti-idiotype antibody). Spleen cells from TNP-F immune NZB mice fail to transfer anti-idiotype antibody-mediated suppression to naive mice as do spleen cells from immune non-autoimmune-prone mice. Taken together these data suggest that autoimmune-prone mice are deficient in auto-anti-idiotype antibody-mediated downward regulation of their immune responses. It was further shown that the immune response of NZB mice to TNP-F shows a slower decline in splenic PFC and a greater heterogeneity of PFC affinity than do the responses of non-autoimmune-prone strains. Since athymic (nude) mice, which were previously shown to be defective in the production of auto-anti-idiotype antibody, also show a slower decline in splenic PFC and an increased heterogeneity of PFC affinity, it is suggested that these peculiarities of the immune responses of autoimmune-prone and athymic mice are also the consequences of the lack of auto-anti-idiotype antibody-mediated down-regulation.     

Regulation of cGMP production by intracellular alkalinization in cultured rat inner medullary collecting duct cells

We evaluated the relationship between cell pH and cGMP production in cultured rat renal inner medullary collecting duct cells. The cGMP level, 21 +/- 6, was not different in control vs. alkalinized cells, 49 +/- 17 fmol/mg protein (p greater than 0.5). 10(-11) M atrial natriuretic peptide (ANF) enhanced cGMP production in alkalinized cells, 426 +/- 34 vs. 141 +/- 9*. Conversely, alkalinization inhibited 10(-4)M nitroprusside (SNP) induced cGMP formation, 29 +/- 9 vs. 332 +/- 67*. Phosphodiesterase inhibition abolished the difference in cGMP production by ANF but did not reverse the inhibitory effect of alkalinization on SNP induced cGMP production. In rat renal inner medullary collecting duct cells, cellular alkalinization plays a significant role in the regulation of guanylate cyclase mediated cGMP production. * = p less than 0.05).     

Studies on the control of antibody synthesis. IX. Effect of boosting on antibody affinity.

The effect of boosting on antibody affinity was studied in a haptenic system. Generally, boosting results in the prompt synthesis of high affinity anti-hapten antibody. However, repeated boosting frequently leads to a decrease in the amount and affinity of the serum antibody. Repeated boosting with hapten on a carrier different from that used for priming selectively stimulates synthesis of the highest affinity anti-hapten antibody and does not result in a decrease in affinity. Priming with soluble antigen without adjuvants results in the synthesis of low affinity antibody. After such priming, boosting stimulates low affinity antibody synthesis and repeated boosting leads to a moderate increase in antibody affinity.     

Studies on antigenic competition. V. Evidence for the involvement of a thymic-derived cortisone-sensitive cell in the mediation of antigenic competition

Animals depleted of lymphoid subpopulations by neonatal thymectomy, by adult thymectomy, irradiation, and bone marrow reconstitution, or by hydrocortisone treatment did not exhibit antigenic competition. In contrast, injection of anti-lymphocyte serum, while depressing the magnitude of the immune response, did not effect antigenic competition. It is concluded that a thymic-dependent cortisone-sensitive cell population is involved in the initiation of antigenic competition.     

Studies of immune responses in mice prone to autoimmune disorders: I. Heterogeneity of the affinities of antihapten antibodies produced by NZB,NZW, and related strains of mice

Mice of the NZB and NZW strains and their F₁ hybrid produce antihapten plaque-forming cell (PFC) responses to T-dependent antigens (trinitrophenylated bovine gamma globulin and dansylated keyhole limpet hemocyanin) which are of unusually restricted heterogeneity of affinity, are relatively lacking in low-affinity PFC, and are of relatively high average affinity. Since some low-affinity PFC are present in NZB mice early after immunization, the results suggest a particularly marked down-regulation of low-affinity antibody production by these strains. The non-autoimmune-prone F₁ hybrid (NZB × CBA) produces a typical heterogeneous response containing a high proportion of low-affinity PFC. Thus, the tendency to down-regulate low-affinity PFC is not inherited as a simple Mendelian dominant trait. The response of NZB mice to T-independent antigens does not show the same restricted heterogeneity of affinity. In fact, late after injections of trinitrophenylated Ficoll, NZB mice tend to have more heterogeneous responses than nonautoimmune-prone BALB/c mice in which a marked down-regulation of high-affinity antibody-producing PFC is seen. The possible relationship between these unusual features of the immune response of NZB and some related strains and their tendency to develop autoimmune disease is discussed.     

The plaque-forming-cell (PFC) response of human blood lymphocytes. II. PFC response by mixtures of allogeneic lymphocytes cultured with formalin-treated staphylococci

Formalin-treated Staphylococci (FSA) induce anti-SRBC PFC in cultures of human lymphocytes. Regulation of the PFC response induced by FSA in cultures containing lymphocytes from two allogeneic donors was studied. The PFC response observed in such cocultures could not be predicted from the responses of lymphocytes from the two donors cultured individually. The PFC response of approximately one half the cocultures was less than expected. The remaining cocultures generated more PFC than expected. The depression or augmentation in the PFC response which was observed in cocultures was reproducible when lymphocytes from the same pair of donors were cocultured. Cocultures containing lymphocytes from identical twins generated the expected PFC response. The data suggest that suppressor or helper activity may be generated during a “two-way” allogeneic mixed lymphocyte reaction (MLR). Much less deviation from the expected PFC response was observed during a “one-way” MLR. Anti-Ia antiserum treatment of either donor's lymphocyte population tended to eliminate the deviation from the expected PFC response in coculture. The data suggest that a feedback loop, involving cells from both donors, may be operating in the “two-way” MLR, which leads to the generation of suppressor or helper activity.     

Selective immunodepression

A variety of experimental conditions have been described which can selectively depress various aspects of the normal immune response. Treatment with cytotoxic drugs or variations in the route of administration or physical state of the antigen can selectively depress one immunoglobulin class while allowing normal synthesis of other immunoglobulin classes. Injection of excessive or subimmunogenic doses of antigen, or injection of antigen in a nonimmunogenic form will specifically depress antibody body syntheis to that antigen. Depending upon the antigen dose and other factors discussed above such tolerance can be selectively induced in either the B- or the T-lymphocyte population. Finally, antibody is highly heterogeneous with respect to its affinity for the antigenic determinant. As a consequence of the selective pressure of decreasing antigen concentration there is generally a progressive shift towards the production of high affinity antibodies. Various experimental maneuvers can selectively depress specific subpopulations of antibody forming cells. B-cell tolerance preferentially occurs in high affinity antibody forming cells with a decrease in the average affinity of the residual antibody formed. Passively injected antibody specifically depresses antibody synthesis to concomitantly injected antigen. This antibody mediated immune suppression selectively depresses low affinity antibody synthesis. Thus, a variety of experimental procedures have been discussed which will modify the immune response in highly selected ways.It is clearly important in describing the immune response to specify not merely the amount of antibody formed, but also its class and subclass. In addition, to fully describe the immune response it is necessary to specify the affinity and heterogeneity of the antibody. As discussed above the factors controlling the affinity of serum antibody and the mechanism of antibody mediated immune suppression are reasonably well understood. Much data are available regarding factors determining tolerance induction, however, the detailed cellular mechanisms involved remain obscure. With regard to the mechanisms determining which immunoglobulin classes are formed, and in what proportion, relatively little information is available.     

Cellular basis for a hapten-specific state of tolerance induced in vitro.

A hapten-specific unresponsive state was induced in vitro by the incubation of normal murine spleen cells with highly conjugated dinitrophenylated bovine gamma-globulin (DNP-BGG) or a dinitrophenylated copolymer of D-glutamic acid and D-lysine (DNP-D-GL) for 24 hr. After this incubation period spleen cells were washed and cultured for 4 days with the thymic-independent antigen dinitrophenylated polyacrylamide beads (DNP-PAA) or the thymic-dependent antigen trinitrophenylated burro the erythrocytes (TNP-BRBC). Preincubation with either DNP-BGG or DNP-D-GL led to a specific depression of the in vitro anti-hapten plaque-forming cell response. The degree of depression was dependent upon the concentration of the tolerogen and the duration of preincubation. The response to DNP-PAA or TNP-PAA beads was depressed to a greater degree than was the response to TNP-BRBC. The cellular basis of the immunologic unresponsiveness induced by DNP-BGG was attributable to an inhibition of B cell function whereas the unresponsive state induced with DNP-D-GL was due to both a specific inhibition of B cell function and the activation of antigen-specific suppressor T cells.     

Papers to appear in forthcoming issues

Tolerance to the TNP haptenic determinant was induced by a single intravenous injection of trinitrophenylated syngeneic cells. Syngeneic spleen or thymus cells were capable of acting as carriers for tolerance induction while syngeneic bone marrow cells were not. Syngeneic spleen cells depleted of θ-positive and adherent cells were also suitable carriers for tolerance induction. Sonicated haptenated spleen cells, but not sonicated haptenated bone marrow cells induced tolerance. The ability of haptenated cells to induce tolerance was not correlated with their localization in lymphoid organs. Furthermore, cells recovered from the spleens of lethally irradiated animals reconstituted with bone marrow cells 1 week previously were incapable of inducing tolerance after hapten-modification. However, after 3 weeks, spleen cells from bone marrow-reconstituted mice had acquired the ability to induce tolerance. These results suggest that only certain types of syngeneic cells have the ability to act as carriers for tolerance induction; merely being syngeneic, and therefore presumably nonimmunogenic, is not sufficient to permit the cell to act as a carrier for tolerance induction.