Immunoregulatory role of Ig isotypes. II. Activation of cells that block induction of contact sensitivity responses by antibodies of IgG2a and IgG2b isotypes

The influence that the isotype of Ag-specific antibody has on the induction of contact hypersensitivity (CS) has been investigated. Injection (i.v.) of mice with haptenated peritoneal exudate cells (PEC) pretreated with anti-hapten mAb of the IgG2a and IgG2b isotypes results in the activation of Ag-specific afferent acting Ts cells (Ts-aff). These suppressor cells are not generated when animals are injected with anti-hapten antibodies of other isotypes. The Ts-aff cells function to inhibit the generation of CS responses when injected into naive animals. Suppression is due to the induction of both Lyt-1+,2- I-J+ and Lyt-1-,2+ I-J+ T cells, both of which adhere to the lectin Vicia villosa. Attachment of both TNP and 4-ethoxymethylene-2-phenyloxazolone haptens to the same PEC, followed by treatment with an IgG2a anti-TNP antibody, generates Ts-aff cells specific for both 4-ethoxymethylene-2-phenyloxazolone and TNP. The MHC haplotype of the PEC is irrelevant, as allogeneic PEC will also induce Ts-aff cells when injected by using an identical protocol. Ts-aff cells cannot be generated in B cell-depleted mice, nor does the Ts-aff cells generated in normal mice suppress CS responses in B cell-depleted mice. These results show that Ag-antibody complexes bound on the surface of a PEC can induce potent afferent suppression in vivo. A possible general role for antibody isotypes in directing regulatory activities is discussed.     

Isotype-specific immunoregulation. Systemic antigen induces splenic T contrasuppressor cells which support IgM and IgG subclass but not IgA responses

In the present study, we have isolated and characterized the Lyt-1+, -2- T contrasuppressor (Tcs) cells from mice systemically primed with SRBC. Adoptive transfer of splenic Tcs cells from these mice abrogates oral tolerance and supports IgM and IgG anti-SRBC plaque-forming cell (PFC) responses; however, unlike the responses seen after transfer of Tcs cells derived from orally primed mice, low IgA responses were seen. Mice systemically primed with lower SRBC doses (0.01 to 1%) exhibited contrasuppression only within the L3T4- T cell subset, whereas mice primed with a high dose of SRBC (10%), harbored Lyt-1+, -2- Tcs cells in both the L3T4+ and L3T4- subsets. Both the L3T4- and L3T4+ Tcs cell subsets supported IgM and IgG responses when adoptively transferred to orally tolerized mice, and when added to tolerized spleen cell cultures. Splenic Tcs cells from systemically primed mice supported mainly IgG1 and IgG2b subclass anti-SRBC PFC responses, a pattern also seen with Tcs cells derived from orally primed mice. Both L3T4+ and L3T4- Tcs cells from systemically primed mice exhibited well established characteristics of contrasuppressor cells including binding to Vicia villosa lectin and expression of I-J. The splenic effector Tcs cells which support IgM, IgG1 and IgG2b anti-SRBC PFC responses are antigen-specific, since both L3T4- and L3T4+ Tcs cells from spleens of mice primed with 10% SRBC reverse tolerance to SRBC, but not to horse erythrocytes (HRBC). Further, both L3T4- and L3T4+ Tcs cells from HRBC-primed mice reverse tolerance to IgM and IgG anti-HRBC, but not to anti-SRBC responses. Isolation of T3-positive Lyt-1+, -2- and L3T4- Tcs cell subsets by flow cytometry followed by adoptive transfer, showed that effector Tcs cells express T3 and presumably contain an Ag-R (TCR-T3 complex). These studies show that systemic priming with heterologous RBC induces splenic Ag specific Tcs cells in a dose-dependent manner, which support IgM and IgG subclass responses, but not IgA responses.     

Suppression and contrasuppression in the induction of contact sensitivity by the administration of cellbound antigen-antibody complexes

The tolerogenic signal produced by the i.v. injection of haptenated peritoneal exudate cells can be converted to an immunogenic signal by treating the cells with antibody to the hapten before administration. We examined this phenomenon and found that immunity induced by antigen-antibody complexes, as opposed to skin sensitization, is resistant to suppressor T cell influences. This resistance to suppression is due to the activation of an I-J+, Ly-1 T cell population which adheres to the Vicia villosa lectin, all characteristics of contrasuppressor T cells. Because haptenated cells can induce immunity if injected subcutaneously or into cyclophosphamide-pretreated recipients (thereby avoiding the induction of suppressor cells), we suggest that the activation of contrasuppressor cells by antigen-antibody complexes overrides suppressive influences in the host, allowing immunity to become dominant. The possible roles of suppression and contrasuppression in channeling the effector arm of the immune response (e.g., contact sensitivity vs humoral immunity) are discussed.     

Infectious and noninfectious tolerance are blocked by a monoclonal antibody to T-suppressor factor

Two forms of hapten-specific unresponsiveness have been demonstrated following intravenous (iv) injection of hapten-conjugated syngeneic spleen cell based on the nature of the antigen-presenting cell (APC): I-J+, I-A- APC have been shown to induce T-suppressor cells (Ts cells) which are demonstrated upon adoptive transfer, while I-J-, I-A+ APC induce a nontransferable tolerance. In this paper we report that a monoclonal antibody specific for T-suppressor effector cells and factors (14-12) can block the Ts cells induced by I-J+, I-A- APCs and the tolerance induced by I-J-, I-A+ APCs. In addition, it sufficiently overcomes suppression such that injection of TNP-spl iv induces immunity rather than suppression. We show that the I-A+, I-J- TNP-spl, which induce nontransferable tolerance upon iv injection, are the cells which induce immunity in 14-12-treated recipients. These results demonstrate that injection of I-J-, I-A+ APC does not lead to clonal deletion and the tolerance induced by the iv injection of both I-J+, I-A- and I-J-, I-A+ APC operate via Ts cells.     

Contrasuppressor cells that break oral tolerance are antigen-specific T cells distinct from T helper (L3T4+), T suppressor (Lyt-2+), and B cells

Continuous gastric intubation of mice with the T cell-dependent antigen sheep erythrocytes (SRBC) leads to a state of systemic unresponsiveness to parenteral SRBC challenge, a state termed oral tolerance. The systemic unresponsiveness of mice rendered orally tolerant to SRBC, however, is converted to humoral immune responsiveness by adoptive transfer of effector T contrasuppressor (Tcs) cells. In this study, the authors have isolated and characterized the Tcs cell subset, from the spleens of orally immunized mice, which abrogates oral tolerance. This Tcs cell is a novel cell type, which can be separated from functional T suppressor (Lyt-2+) and T helper (L3T4+) cells, and the effector Tcs cell exhibits a Lyt-1+, 2-, L3T4- phenotype. Furthermore, contrasuppression is not mediated by B cells, including those of the Lyt-1+ phenotype. Adoptive transfer of splenic Lyt-1+, 2-, L3T4- T cells from C3H/HeJ mice given oral SRBC for 21 to 28 days and splenic Lyt-1+, 2-, L3T4- T cells of C3H/HeN mice orally immunized for a shorter interval abrogated oral tolerance. Furthermore, separation of Lyt-1+ T cells into L3T4+ and L3T4- subsets by flow cytometry resulted in Lyt-1+, L3T4+ T cells with helper but not contrasuppressor function, whereas the Lyt-1+, L3T4- T cell fraction abrogated oral tolerance even though it was without helper activity. This Tcs cell subset was also effective when added to cultures of tolerized spleen cells derived from SRBC-fed mice. The effector Tcs cells are antigen-specific, because Tcs cells from SRBC-immunized mice reverse tolerance to SRBC but not to horse erythrocytes (HRBC), and Tcs cells from HRBC-immunized mice reverse tolerance to HRBC but not to SRBC. When splenic T3 (CD3)-positive T cells (Lyt-1+, 2-, and L3T4-) were separated into Vicia villosa-adherent and nonadherent subpopulations, active contrasuppression was associated with the T3-positive and Vicia villosa-adherent T cell fraction. Thus, a distinct Lyt-1+, 2-, L3T4- T cell subset that contains a T3-T cell receptor complex, which can regulate oral tolerance, is present in spleens of orally immunized mice.     

Regulation of contact sensitivity reaction: contrasuppressor T cells and contrasuppressor factor downregulate efferent T suppressor cells.

Contact sensitivity (CS) reaction mediated by CD 4+8- Th 1 cells is under the control of several antigen-specific regulatory lymphocytes. Reaction is downregulated at the induction stage by T afferent suppressor T cells (Ts-aff) that prevent immunization and at the effector stage by efferent T suppressor cells (Ts-eff) that made immune Th 1 cells inoperative. Both suppressor cells are CD 4-8+ Th 1 effector cells and are protected against the suppressive action of Ts-eff cells by CD 4+8- contrasuppressor T cells (Tcs). As has been already shown there are also regulatory interactions between regulatory cells themselves and Ts-aff cells in addition to their effect on precursors of Th 1 cells, also preventing the induction of Ts-eff cells. The present experiments extend these findings and demonstrate that Ts-eff cells are also under negative control of Tcs lymphocytes. Likewise, antigen-specific factor produced by contrasuppressor T-T cell hybridoma, used in lieu of Tcs cells, impedes the activation of Ts-eff cells. In both cases regulation is aimed at the precursors of Ts-eff cells. Our experiments demonstrate that the outcome of immunization is dependent not only on the balance between immune cells and regulatory cells, but also on interactions between regulatory cells themselves.     

On the control between cell-mediated, IgM and IgG immunity

An hypothesis is proposed here describing some of the conditions that determine the type of response an antigen will induce, and explaining how the induction of one type of immunity affects the induction of other types of immunity. In more detail, the hypothesis attempts to account for the following observations: Some antigens induce only cell-mediated immunity, whereas others can, under different conditions, induce either cell-mediated or humoral immunity. The humoral response to most antigens consists of an initial period of IgM antibody synthesis, followed by a period of IgG synthesis. Some polymeric antigens induce the synthesis of only IgM antibody. There is a tendency for the immune response to an antigen, at a particular time, to be exclusively of the cell-mediated, IgM or IgG type.The hypothesis may also be relevant to some observations that, I believe, have been incorrectly interpreted to mean that “tolerance” to some antigens requires the presence of T (thymus-derived) cells specific for these antigens. The hypothesis suggests teleological reasons for the existence of the different types of immunity. It also suggests ways of controlling the type of response an antigen induces.     

Antigen-specific T contrasuppressor factor in cell-mediated immunity: interactions leading to eradication of the tolerant state

Interactions between a T cell-derived, antigen-specific, contrasuppressor factor (TcsF) and immune T cells that block the action of T suppressor factors and allow the transfer of cellular immunity into tolerant recipients are described. Immune T cells from contact-sensitized donors are capable of transferring specific immunity into normal recipients but not into animals rendered tolerant to the specific antigen. Brief exposure of the immune cells to the TcsF enables the effective transfer of immunity into such tolerant recipients. In addition, treated immune cells become resistant to subsequent exposure to T suppressor factor (capable of inhibiting transfer of immunity to normal recipients). A cyclophosphamide-sensitive, I-J+, Ly-2 T transducer cell is required in the immune donor cell population for contrasuppression to be induced by the TcsF plus specific antigen. These cells release an antigen-non-specific contrasuppressive factor capable of rendering immune targets, depleted of transducer cells, resistant to suppression (either by suppressor factor or in the tolerant recipient). The results indicate that contrasuppression in contact sensitivity is antigen specific and that the balance of suppression and contrasuppression determines tolerance vs responsiveness in this system. The symmetrical resemblance of the contrasuppressive interactions to those of suppression in contact sensitivity are discussed.     

Regulatory function for murine intraepithelial lymphocytes. Two subsets of CD3+, T cell receptor-1+ intraepithelial lymphocyte T cells abrogate oral tolerance

The murine intraepithelial lymphocyte (IEL) population is enriched in T cells that express the gamma delta-TCR, however, the biologic function served by these T cells remains obscure. IEL are considered to be major effector cells in mucosal immunity, and we have investigated whether IEL subsets could reverse orally induced systemic unresponsiveness (oral tolerance; OT) and support secondary type responses when adoptively transferred to mice orally tolerized with SRBC. When purified CD3+ IEL from mice orally primed with SRBC were transferred to adoptive hosts and challenged with SRBC, splenic IgM, IgG1, IgG2b, and IgA anti-SRBC plaque-forming cell responses were observed. However, CD3+ IEL from HRBC orally primed mice did not abrogate SRBC induced OT. Further, HRBC-primed CD3+, IEL converted HRBC-specific OT but not SRBC-specific OT. CD3+ IEL could be separated into four subsets based on expression of CD4 and CD8. CD3+, CD4-, 8+ T cells were the major subset (74.5%), with smaller numbers of CD4- and CD8- (double negatives, DN) (7.8%), CD4+, 8- (7.6%) and CD4+, CD8+ (double positives) (10.1%) T cells. Interestingly, both the CD3+, CD8+, and the CD3+, DN IEL subsets abrogated OT, resulting in significant IgM, IgG1, IgG2b, and IgA anti-SRBC plaque-forming cell responses when adoptively transferred to mice with OT. However, neither CD3+, CD4+, CD8-, nor double positive T cells affected OT when studied in this system. The CD3+, CD8+ IEL subset could be further separated into Thy-1+ (16.6%) and Thy-1- (83.4%) cells; adoptive transfer of Thy-1- cells abrogated oral tolerance whereas the Thy-1+ subset was without effect. When the expression of TCR on IEL with this biologic function was determined by use of monoclonal anti-alpha beta TCR (H57.597), TCR2-, CD3+ IEL possessed immunoregulatory function whereas the alpha beta-TCR+ (TCR2+) fraction did not abrogate OT. Immunoprecipitation of membrane fractions obtained from purified CD3+, CD4-, CD8+, Thy-1- IEL with polyclonal anti-delta peptide (Tyr-Ala-Asn-Ser-Phe-Asn-Asn-Glu-Lys-Leu) antibody revealed bands of 45 and 35 kDa, corresponding to the delta- and gamma-chains, respectively. These results suggest that gamma delta-TCR+ IEL possess a regulatory function, namely the restoration of immune responses in a state of oral tolerance. Further, both CD3+, CD4-, CD8+, Thy-1-, and CD3+, DN IEL T cells exhibit this effector contrasuppressor function.     

Influence of contact sensitivity to DNFB on the induction of carrier-determined tolerance to DNP.

Contact sensitivity to DNFB, induced by skin painting Balb/c mice with DNFB had no influence on the induction of carrier determined tolerance to DNP. In contrast, contact sensitivity to DNFB, elicited in complete Freund's adjuvant, prevented induction of tolerance to DNP. This effect was not due to the adjuvant alone and was hapten specific since contact sensitivity induced by OCBC in complete adjuvant had no influence on tolerance induction to DNP. In addition, in mice primed with DNFB in complete Freund's adjuvant, the tolerogen becomes immunogenic. It is suggested that the T-cell mediating tolerance to DNP-autologous IgG is different from the T-cell mediating contact sensitivity to DNP autologous carrier. DNFB in complete adjuvant may augment not only contact-sensitized T-cells, which mediate contact sensitivity, but also T-cells which have helper function in the antibody response to DNP.     

Characterization and activity of contrasuppressor T cells induced by type III pneumococcal polysaccharide

Optimally immunogenic amounts of type III pneumococcal polysaccharide (S3) activate a population of contrasuppressor T cells (Tcs), which have been shown to play an important role in the induction of anti-S3 antibody responses. These Tcs belong to a unique T cell subset that has the surface phenotype Lyt 1+2- L3T4- I-J+ I-A+. These Tcs are also cyclophosphamide (Cy)-sensitive and sensitive to antilymphocyte serum (ALS) and mitomycin C. Tcs have antigen-binding receptors, indicating that any interactions of Tcs with B cells or T suppressor cells (Ts) (both of which also have antigen-binding receptors) must be via an antigen bridge rather than an idiotype-anti-idiotype interaction. Tcs are also Igh restricted in their action. Contrasuppression is manifest only when the Tcs are Igh compatible with both the Ts and the responding B cells. Tcs apparently mediate their effects by releasing a soluble factor, since a soluble factor extracted from Tcs is able to abrogate the effects of S3-specific Ts.     

Requirements for activation of contrasuppressor T cells by type III pneumococcal polysaccharide

Either S3-coupled spleen cells (S3-SC) or soluble S3 activates two populations of regulatory T cells, T suppressor cells (Ts) and contrasuppressor T cells (Tcs). The latter cells function to mask the activity of Ts in unfractionated T cell populations, so that Ts can be detected only after removal of Tcs. Activation of Tcs by S3 may be required for induction of an antibody response to S3. This is suggested by the findings that Tcs are activated only by immunogenic doses of S3, that Tcs are not detectable in the spleens of mice tolerant to S3, and that (CBA/N X BALB/c)F1 male (xid) mice, which are genetically unresponsive to S3, do not develop Tcs after immunization with S3. Moreover, the kinetics of activation of Tcs by S3 closely parallels the kinetics of the antibody response to S3. Tcs have no detectable activity in the absence of Ts, indicating that these cells do not function as amplifier or helper T cells.     

Induction and properties of DNP-specific T cells in mice sensitized to DNP-coupled mycobacterium.

Splenic T lymphocytes from mice sensitized to 100 microgram of DNP-coupled mycobacterium (DNP-Tbc) showed in vitro proliferative response against DNP- or TNP-conjugated protein antigens. The increased uptake of 3H-thymidine induced by DNP-HSA was partially inhibited by the addition of 10(-4)M DNP-EACA. DNP-AECM-Ficoll did not induce any significant proliferative responses in DNP-Tbc-primed T cell population. However, priming with DNP-Tbc augmented anti-DNP IgG antibody response induced with DNP-Ficoll. The augmentation of IgG response was not due to the presence of DNP-primed B cells or anti-DNP antibody. The results showed that the priming with DNP-Tbc induced DNP-reactive T helper cells which could be triggered with DNP-Ficoll. The possible role of mycobacterium in the induction of hapten-specific T helper cells is discussed.     

Requirement for B cells for activation of contrasuppressor T cells by type III pneumococcal polysaccharide

Type III pneumococcal polysaccharide (S3) is unable to activate S3-specific contrasuppressor T cells (Tcs) in mice depleted of B cells by chronic anti-IgM treatment or in immune defective xid mice that lack the B cell subset required for anti-S3 antibody responses. The inability of S3 to activate Tcs in xid mice was shown to be due to a requirement of B cells for Tcs activation rather than to an absence of Tcs in xid mice. The B cells from normal mice that are required for Tcs activation apparently function to present the S3 Ag to Tcs. S3 physically coupled to spleen cells (S3-SC) prepared from normal BCF1 SC could activate Tcs in both xid and BCF1 mice whereas S3-SC prepared from xid SC or B cell-depleted BCF1 SC could not activate Tcs in either strain. B cell APC function was abrogated by 3000 R irradiation and by treatment of the B cells with either chloroquine or paraformaldehyde. Interestingly, B cells from mice previously immunized with S3 were unable to function in Tcs activation; preimmunization of B cell donors with an irrelevant Ag or with a T-dependent form of S3 had no effect on their ability to function as APC. These latter observations are discussed in terms of the in vivo persistence of polysaccharide Ag and their ability to induce B cell tolerance under the experimental conditions used for these experiments. The results of this study provide evidence that B cells play an important and apparently obligatory role in the activation of Tcs by S3; B cells apparently function to present Ag to Tcs, resulting in the activation of this regulatory T cell subset.     

Hapten-specific carrier-dependent tolerance induction in man in vitro

We sought to determine whether hapten-specific tolerance can be induced in cultured human lymphocytes in vitro. Unfractionated as well as T and B cells from peripheral blood lymphocytes of healthy human volunteers were cultured with different hapten-carrier conjugates before in vitro challenge with dinitrophenyl (DNP) linked to keyhole limpet hemocyanin. Hapten-specific antibody was detected in the supernatant by solid-phase radioimmunoassay. Both hapten specificity and carrier dependence in addition to the cellular basis of tolerance induction were examined. The results show that hapten-specific tolerance of antibody production was induced by human gamma-globulin (HGG) conjugated to DNP but not by other conjugates of DNP nonhuman gamma-globulin, as well as human serum albumin. Moreover, both T and B cells are involved in tolerance induction to DNP-HGG in vitro. The significance of tolerance in human in vitro for the specific therapy of autoimmune disease is discussed.     

Production of antigen-specific contrasuppressor cells and factor, and their use in augmentation of cell-mediated immunity

A single injection of TNP-labeled mouse gamma-globulin (TNP-IgG) can render the contact sensitivity response of mice resistant to suppressor cells (Tsc) and their biologically active cellfree products (TsF). Lyt-1 T cells of mice treated with TNP-IgG can protect the adoptive contact sensitivity response of immune cells from the antigen-specific suppressive effect produced by the addition of antigen-specific TsF or Tsc. When T cells of TNP-IgG-treated mice are put into culture, they produce an antigen-specific contrasuppressor factor (TcsF) that can replace the activity of the cells. When immune cells are preincubated in vitro with TcsF, they become refractory to Tsc and TsF added subsequently. The TcsF, however, has no ability to restore responsiveness to immune cells that had been previously exposed to TsF. The TcsF binds specifically to TNP, expresses an I-J-controlled determinant, and does not express standard determinants found on mouse Ig. The treatment that primes the contrasuppressor system to protect the contact sensitivity response also reportedly renders the antibody-producing system tolerant, (i.e., produces so called "split tolerance"). These results are discussed in light of the possibility that the contrasuppressor system can be responsible for so called isotype-specific immunity by rendering one arm of the immune system resistant to generalized suppressive mechanisms.     

IgE and IgG are synergistic in antigen-mediated release of thromboxane from human lung macrophages.

The mechanism of IgE-mediated release of thromboxane A2 from human lung macrophages has been studied using a monoclonal chimeric human/mouse IgE antibody and its specific antigen. The cells could be sensitized at 37 degrees C but not at 4 degrees C by incubation with IgE, and released a significant amount of thromboxane A2 (TXA2), measured as the stable hydrolysis product TXB2, in response to an anti-chimeric IgE antibody. In contrast, stimulation of IgE-sensitized macrophages with the specific antigen produced less than 10% of this response. A similar time course for the release of TXB2 and the formation of inositol monophosphate in the presence of LiCl was observed. Cleavage of the Fc domain of the anti-chimeric IgE antibody substantially eliminated its capacity to stimulate IgE-sensitized cells. However, the weak or undetectable response to chimeric IgE plus specific antigen was substantially potentiated by an antigen-specific chimeric IgG antibody. IgG-sensitized macrophages did not respond to antigen challenge by the release of TXB2. Preincubation of the cells with a monoclonal antibody against the low affinity receptor for IgE (Fc epsilon RII/CD23) did not prevent IgE sensitization. We conclude that cell-bound IgE antibody cannot induce the release of TXB2 but has fixed antigen which then must interact with specific IgG antibody and IgG receptors to induce mediator release.     

Gamma delta T cells assist alpha beta T cells in adoptive transfer of contact sensitivity.

Cutaneous immune responses to contact sensitizers such as picryl chloride or oxazolone, are classical manifestations of T cell-mediated immunity in vivo. In fact, the first documentation of T cell-mediated immunity was the ability to adoptively transfer contact sensitivity (CS) responses. Although it is now clear that Ag/MHC-restricted alpha beta TCR positive effector T cells are responsible for 24 to 48 h CS responses, other subsets of Thy-1+ cells in mice also participate in the elicitation of CS. Thus, Thy-1+, CD5+, CD3-, B220+, hapten-specific, non-MHC-restricted early-acting cells are required to initiate CS responses by leading to local serotonin release, which allows for extravascular recruitment of the late-acting, alpha beta TCR+, CS effector T cells. This study describes another T cell population that is needed for the adoptive transfer of CS by alpha beta T cells. In vitro treatment of a mixture of CS effector cells with hamster mAb to gamma delta TCR, together with rabbit complement, or by panning on anti-hamster Ig-coated dishes, diminished substantially the subsequent transfer of CS reactivity without affecting either CS-initiating cells, or the later-acting, alpha beta TCR+ CS effector T cells. Immune cells treated with anti-alpha beta TCR mAb, or recovered as adherent cells from petri dishes after anti-gamma delta TCR panning (i.e., gamma delta TCR-enriched cells), reconstituted the ability of anti-gamma delta TCR-treated immune cells (i.e., alpha beta TCR-enriched cells) to transfer 24-h CS responsiveness. The phenotype of the gamma delta T cells that assisted CS effector alpha beta T cells was: CD3+, CD4-, and CD8+. The gamma delta T cells that assisted alpha beta T cells were not Ag-specific since anti-alpha beta-TCR-treated cells (gamma delta T-enriched) from picryl chloride immunized donors aided alpha beta T cells (anti-gamma delta TCR-treated) from oxazolone-immunized donors, and conversely gamma delta T cells from oxazolone-immunized donors aided alpha beta T cells from picryl chloride immunized donors. Furthermore, the CS-regulating gamma delta T cells were not MHC-restricted because gamma delta T cells from H2d or H2b donors could assist alpha beta T cells from H2k donors. It was concluded that a regulatory population of non-Ag specific, non-MHC-restricted gamma delta T cells was needed to assist immune effector, Ag/MHC-specific alpha beta T cells in the adoptive transfer of CS.     

The immune response and the eye. II. The nature of T suppressor cell induction in anterior chamber-associated immune deviation (ACAID)

We studied the cellular basis for the induction of Ts cells in anterior chamber (AC)-associated immune deviation (ACAID) by using TNP-modified syngeneic spleen cells (TNP-Spl). We demonstrate that the cells responsible for the induction of TNP-ACAID are non adherent, IA- T cells. This is in contrast to the antigen-presenting cells which induce suppression after the i.v. injection of TNP-Spl which are IA+/I-J+ adherent cells. Furthermore, two T cells within the TNP-Spl population are required to initiate suppression in TNP-ACAID: one is Lyt-1+, and I-J+, the other is Lyt-1+ and reactive with a monoclonal antibody, 14-30, which specifically identifies Ts inducer cells. The antigen specificity of ACAID resides in the 14-30+ T cell, and not the I-J+ cell. Although both cells must be viable to induce suppression, neither they (nor their products) must be in direct contact within the eye; one population may be in the right AC, the other in the left. Our results suggest that it is Ts inducer cells placed into the AC of the eye which initiate TNP-ACAID, and that these cells exit (or secrete Ts factors which exit) the eye to induce Ts effector cells in the spleen.     

Stability of IgG isotypes in serum

Drug development from early discovery to late stage commercialization is a long arduous process where a number of factors are taken into consideration when deciding on a particular immunoglobulin isotype for a therapeutic purpose. There are no general rules for which isotype is selected; however, prior experiences, effector function and the specific therapy targeted, as well as extensive testing early in development help in paring the number of candidates. Over 20 monoclonal antibodies are FDA-approved, and most are IgG1 isotype, although a number of non-IgG1 molecules have been approved recently and the number in development is on the rise. Analytical techniques that examine the physicochemical properties of a molecule provide vital information on the stability and efficacy of candidate antibody therapeutics, but most of these studies are conducted using standard buffers and under well defined storage conditions.It has recently become apparent that analysis of antibody therapeutics recovered after circulation in blood show altered physicochemical characteristics, and in many instances therapeutic molecules recovered from serum show lower potency. This review examines some of these studies, with a focus on the physicochemical changes observed in the molecules. Technologies that can facilitate rapid screening of candidate antibody therapeutics directly from blood are highlighted. The facts indicate that antibody therapeutic development programs must incorporate understanding of the basic biology of the isotype and its stability in serum, which is the intended environment of the therapeutic.Key words: serum, IgG isotypes, IgG1, IgG2, IgG3, IgG4, stability, primary, secondary, tertiary, Fab exchange, disulfide