Regulation of the immune system by synthetic polynucleotides. V. Effect on cell-associated immunoglobulin receptors and immunological memory

Studies on interference with tolerance induction in T cells

The mechanism of T-cell tolerance to a thymus-dependent antigen was examined, using the adjuvant polyadenylic-polyuridylic acid (poly A:U). In adoptive transfer experiments, thymus cells obtained from donor mice 2 days after treatment with a tolerogenic dose of bovine gamma-globulin (sBGG) did not cooperate with bone marrow (BM) cells in irradiated recipients challenged with aggregated BGG (aBGG). In contrast, thymus cells from donors given sBGG plus poly A:U retained their helper activity, as assayed by hemagglutination and rosette formation of spleen cells. The effect of poly A:U in preventing tolerance induction was also demonstrable in the cortisone-resistant population, in that thymus cells from cortisone-treated donors that had received sBGG and poly A:U retained their helper function. The presence of suppressor cells and the effect of poly A:U on their stimulation were also examined. sBGG-treated thymus cells suppressed the response of BGG-primed spleen cells in lethally irradiated mice, whereas thymus cells from donors treated with sBGG and poly A:U were not suppressive. These observations show that poly A:U prevents tolerance induction and the development of suppressor activity in T cells.

Polyadenylic acid-polyuridylic acid (poly A : U) and experimental murine brucellosis. II. Macrophages as target cells of poly A : U in experimental brucellosis

Results of in vivo and in vitro experiments suggest that the early suppression of brucella growth in double stranded polyadenylic-polyuridylic acid-(poly A:U-) treated mice was due to a non-specific activation of macrophages by poly A:U. Poly A:U administered intraperitoneally at the time of brucella infection failed to enhance T-cell mediated responses to the organism, namely delayed-type hyper-sensitivity to brucellin and adoptive transfer of immunity to the infection. Poly A:U did not augment the protective antibodies formed in response to infection. Although poly A:U has been previously found to suppress brucellosis in athymic (nude) mice, it did not enhance the thymus-dependent antibody response to sheep erythrocytes in brucella-infected nudes, suggesting that it did not significantly enhance maturation of their helper T-cell percursors.

Increased macrophage spreading, an indication of activation, was seen immediately after administration of poly A:U and Brucella abortus. Later on the infection spreading was suppressed, a phenomenon which appears to relate to the biphasic effect of poly A:U in vivo described in the accompanying paper. Peritoneal macrophages treated in vitro with poly A:U were stimulated to spread on plastic surfaces, even when T lymphocytes were removed with anti-Thy-1 serum and complement.

In vitro tolerance induction to a thymus-dependent antigen with BALB/c and C57BL/6 lymph node cells: effect of tolerogen concentration and duration of exposure

Further studies on tolerance induction in vitro to bovine gamma globulin (BGG) in nonadherent BALB/c lymph node cells showed that it was dependent upon both the dose of tolerogen and the time of exposure. Nearly complete tolerance was achieved at a dose of 1.0 mg/ml and an incubation time of 12-18 hours. When C57BL/6 strain was used for comparison with the BALB/c strain because of its relative ease to become tolerant after in vivo injection of tolerogen, the rate of tolerance induction of its nonadherent lymph node cells was not different from that of BALB/c cells. Thus, in the absence of other host factors, the acquisition of tolerance by lymphocytes is gradual and may reflect the time required for a cell to reach a susceptible phase of the cell cycle and/or the activation of suppressor cells.

Kinetics of monocyte receptor activity for immunoproteins in patients with sarcoidosis

Peripheral blood monocytes from patients with active sarcoidosis have increased ability to bind IgG-antibody-coated and C3-coated erythrocytes. Binding of monocytes from sarcoid patients is inhibited less than for normals with IgG1 and IgG3 in the fluid phase. Following phagocytosis of latex particles, monocytes from sarcoides patients retain the capacity to bind IgG-coated erythrocytes, whereas monocytes from normal individuals show disappearance of IgG receptors followed by recovery during a 6-8 hr period. Preliminary studies (8 patients) of monocytes from patients with Crohn's disease show some increase in binding of IgG-coated erythrocytes as compared with normals; this increase, however, is less than for sarcoidosis patients. Preliminary experiments with multistranded polynucleotides (poly I:C:U) show increased activity for normal monocytes and no detectable effect on IgG receptor activity for sarcoid monocytes. Thus peripheral blood monocytes of patients with sarcoidosis have increased IgG and C3 receptors sites, suggesting activation of monocytes in this disease and perhaps in other granulomatous disorders.

Relation between enhanced antibody responses elicited by adjuvant injection and those elicited by secondary antigenic stimulation

An attempt was made to determine if there is any common mechanism in the enhanced antibody response caused either by injection of adjuvant, such as bacterial endotoxin (LPS) and complexed poly-nucleotides, or by secondary antigenic stimulation. LPS inoculated in mice 4 days before injection of sheep red cells (SRBC) and polyA:U invalidated the adjuvant effect of polyA:U injected together with SRBC, and the hemolysin plaque-forming cell (PFC) response of such mice was similar to that of the mice which received SRBC alone. When mice primed with SRBC 24 days in advance were injected with LPS and 4 days later re-stimulated with SRBC, their PFC response to the secondary stimulation was suppressed to less than one tenth of the normal secondary PFC response. The suppressive effect of LPS on the secondary antibody response was abolished if the serum collected from mice injected with LPS was given to the primed and LPS-injected mice at the time of the secondary antigenic stimulation. From these results we discussed the possibility that some common mediator might play a role in the enhanced antibody response elicited by either adjuvant injection or secondary injection of antigen.

Studies on membrane-bound receptors for antigen. Preparation of populations of receptor-depleted lymphocytes

THE EFFECT OF POLYADENYLIC: polyundylic acid complexes (poly A:U) on the amount of antibody on the surface of various populations of mouse lymphoid cells has been investigated by means of a sensitive measure of such activity-the binding by primed cell populations of beta-galactosidase (betaGZ) as an antigen. The sensitivity derives from the liberation of fluorescein from an artificial substrate, fluorescein-di-beta-galactopyranoside (FDbetaG). After incubation with 100 ng/ml of poly A:U, only 40% of the cells previously showing antigen-binding were still active. The optimum range of activity lay between 0.01-1.0 microg/ml poly A:U. Such cells showed increased RNA and protein synthesis as indicated by [(3)H]uridine and [(14)C]amino acid incorporation. The polynucleotide effect was abolished by incubation of the cells with sodium azide or iodoacetate, but not by puromycin. When the proteins on the cell surface were labeled by (125)I, poly A:U caused their release into the medium. Reports by others that the enhancing effect of polynucleotides on the immune response involves the adenylcyclase system are consistent with the finding reported here that reduction of binding by dibutryl 5'-cyclic monophosphoric acid (cAMP) and poly A:U were parallel in extent, and that theophylline and poly A:U acted synergistically in suboptimal concentrations of each.

Surface antigens of immunocompetent cells. 3. In vitro studies of the role of B and T cells in immunological memory

The effect of preincubation with anti-theta or anti-mouse immunoglobulin (Ig) and complement (C') on immune responsiveness of spleen cells from BALB/c mice immunized with sheep erythrocytes (SE) was investigated. Both treatments greatly depressed the remaining ability to produce a secondary response to SE in vitro. Normal BALB/c spleen cells were far less effective in reconstituting the responses of such depleted cell populations than were much smaller numbers of untreated immune spleen cells. Thymus-derived cell (T cell) memory appeared early after immunization and showed specificity for the immunizing antigens. Recombination of anti-Ig-treated with anti-theta-treated immune spleen cells resulted in virtually complete reconstitution of responsiveness. The presence of immunological memory in T cells and the nature of their surface receptors are discussed.