Requirement for matching T cell and B cell subsets in secondary anti-hapten antibody responses

An Immunoadhesin Incorporating the Molecule OX-2 Is a Potent Immunosuppressant That Prolongs Allo- and Xenograft Survival

We have established that, in mice receiving donor-specific immunization by the portal vein, the increased graft survival seen is associated with the increased expression of a molecule (OX-2) on a subpopulation of dendritic cells (DC), and polarization of cytokine production to type 2 cytokines on Ag-specific restimulation of cells from these mice. Furthermore, infusion of a mAb to OX-2 blocks both the increased graft survival and the altered cytokine production seen. We have constructed an immunoadhesin in which the extracellular domain of OX-2 is linked to the murine IgG2a Fc region, and we have expressed this molecule (OX-2:Fc) in a eukaryotic (baculovirus) expression system. Incubation of lymphocytes with 50 ng/ml OX-2:Fc inhibits a primary mixed lymphocyte reaction in vitro, as assayed by proliferation and induction of cytotoxic T cells, and also alters cytokine production with decreased IL-2 (IFN-γ) production and increased IL-4 (IL-10) production. Similarly, in vivo infusion of OX-2:Fc promotes increased allo- and xenograft (both skin and renal grafts) survival and decreases the Ab response to sheep erythrocytes. Our data suggest this molecule might have clinical importance in allo- and xenotransplantation.

Neuroleptic and anti-depressant drug treatment abolishes conditioned immunosuppression in mice

Mice previously exposed to cyclophosphamide in the presence of saccharin-flavored water will show a decreased antibody response to challenge with sheep erythrocytes if simultaneously they are again given saccharin to drink. These mice also show conditioned taste aversion. Treatment of conditioned animals with chlorpromazine or amitriptyline after challenge with erythrocytes in the presence of saccharin reduced the degree of immunosuppression and, though to a lesser degree, the conditioned taste aversion.

Behavioral trait associated with conditioned immunity

Inbred strains of mice were tested for their activity in an open field. Animals selected for high or low activity ("tails" of the normal distribution) were further inbred through nine generations (brother x sister) with further selection at each generation. Reciprocal skin grafts between the two groups were performed to ensure that little/no genetic drift occurred. Using a cyclophosphamide:saccharin conditioning paradigm (R. Ader & N. Cohen (1975) Psychosom. Med. 37, 333-342) we show that mice preselected for high activity in an open field were those in which it was most easy to demonstrate conditioned immunosuppression. There was no difference in the conditionability of the two groups as assessed by taste aversion. By use of a cross-fostering design we conclude that immunological conditioning (in adult mice) can be affected by a characteristic of the nursing mother which is associated with activity in an open-field trial.

Analysis of lymphocytes in, and host environment of, mice showing conditioned immunosuppression to cyclophosphamide

Mice were subjected to repeated exposures to cyclophosphamide: saccharin (conditioned) or cyclophosphamide:saccharin followed by saccharin only (conditioned:extinguished). Animals in the former group but not the latter subsequently showed diminished IgG antibody-forming cells (AFC) after challenge with sheep red blood cells followed by reexposure to immunologically inert cues (saccharin). When these animals were used as irradiated recipients of syngeneic spleen lymphocytes, reconstituted irradiated conditioned mice showed augmented IgG AFC on transfer of naive spleen cells and reexposure to saccharin. The expected diminished IgG AFC response was seen when cells from conditioned mice were transferred. However, the latter cells gave augmented IgG AFC when transferred to naive irradiated mice. Both of the effects seen with cells from conditioned animals (increased IgG AFC in control recipients; decreased IgG AFC in conditioned mice reexposed to saccharin) were regulated by adoptively transferred T cells in the spleen cell population.

Alteration in lymphocyte recognition repertoire during aging. II. Changes in the expressed T-cell receptor repertoire in aged mice and the persistence of that change after transplantation to a new differentiative environment

Changes in the T-lymphocyte alloreceptor repertoire associated with aging by exploring the frequency of cytotoxic T-lymphocyte precursors (CTLp) available for activation by various major histocompatibility complex (MHC) haplotypes in mice of different ages have been investigated. There was no consistent pattern of change in CTLp frequencies. Thus, for instance, while the frequency of responder C57B1/6 CTLp for ATH alloantigen decreased with age, the frequency for C3H alloantigen increased. There was no significant change in the overall frequency of splenic CTLp (assessed irrespective of antigen specificity). No evidence was found that CTL produced by activated CTLp of aged mice were less specific in their lytic capacity that CTL produced by CTLp of young mice. However, by assaying responder CTLp cultures at limiting dilution we obtained evidence that the "burst size" (mean lytic capacity per responder well assayed at limiting dilution) was diminished with age of the donor of the CTLp pool. Furthermore, we obtained evidence that the apparent affinity of CTL for their target antigen was consistently decreased when those effector cells were derived from a pool of CTLp of aged mice. All of these changes reflected in mature T cells derived from aged mice were already apparent in the bone marrow stem cell pool of aged individuals and were not due to environmental influences alone, as assessed by the phenotype of T cells derived from young or old bone marrow stem cells transplanted to young or aged recipient mice. A final study has examined evidence for more subtle changes in the T-cell alloreceptor repertoire, reflecting heterogeneity in young or aged mice in the recognition repertoire associated with a given antigenic specificity. By preparing F1 anti (parent anti-F1)-suppressor cells directed against CTL from young parental mice (a, b, c), or aged parental mice (x, y, z), we have explored the heterogeneity in the anti-C3H alloreceptor repertoire in individual young or aged C57B1/6 mice. Suppression by immunized F1 animals was assessed in tissue culture (inhibition of mixed lymphocyte culture (MLC) responses) or in vivo (inhibition of lethal GvHD induced by inoculation of parental lymphocytes into sublethally irradiated F1 hybrid mice). Irrespective of the assay system used, the data suggests that the receptor repertoire of aged T lymphocytes uses recognition structures different from those of young individuals, and that there is less individual-to-individual variation in the receptor repertoire of aged mice than in young mice.

T lymphocyte-dependent B lymphocyte proliferative response to antigen. I Genetic restriction of the stimulation of B lymphocyte proliferation

For the purpose of examining more closely the interaction between T and B lymphocytes, we have developed an in vitro T lymphocyte-dependent B lymphocyte proliferation assay. Proliferation of B lymphocytes in response to antigen was found to depend on the presence of primed T lymphocytes; the B lymphocytes could be derived from nonprimed animals. It appears that these B cells were nonspecifically recruited to proliferate. This nonspecific recruitment, however, was found to be Ir-gene restricted in that B lymphocytes from B10.S mice, which are genetic nonresponders to the polymer Glu60-Ala30-Tyr10 (GAT), could not be stimulated by GAT-primed (responder X nonresponder) F1 T cells. The apparent lack of antigen specificity in the face of Ir gene-restricted T-B interaction may have important implications in our understanding of the recognition unit(s) on T lymphocytes.

Individual-specific (idiotypic) T-B cell interactions regulating the production of anti-2,4,6-trinitrophenyl antibody. I. Generation of suppressor T cells and antibody directed against immunocompetent cells

It is known from several experimental systems that the production of dominant antibody idiotypes may be regulated by anti-idiotypic mechanisms. Our aim has been to test whether the potential for such control also exists in the more typical heterogeneous antibody responses of inbred mice to the trinitrophenyl (TNP) hapten, where dominant idiotypes are not recognized. CBA mice were hyperimmunized to trinitrophenylated keyhole limpet hemocyanin. Serum or lightly fixed spleen cells from these mice were injected into normal syngeneic "recipients". The serum and spleen cells from these recipients were found to have the power to suppress in vitro anti-TNP antibody responses made by further spleen cells from the donor mice. This suppression was specifically directed against the cells of the individual donor animals suggesting idiotype-related regulation.

Individual-specific (idiotypic) T-B cell interactions regulating the production of anti-2,4,6-trinitrophenyl antibody. II. Development of idiotype-specific helper and suppressor T cells within mice making an immune response

The previous report demonstrated that serum and cells from CBA mice immunized with trinitrophenyl (TNP), when injected into normal, syngeneic "recipient" mice, induce the formation of apparently idiotype-specific suppressor cells and serum factors, and that such regulatory elements develop within the serum of the TNP-immunized animals themselves. In this report, it is indicated that regulator cells develop also within the spleens of TNP-keyhole limpet hemocyanin-immunized animals, and may in part be responsible for our earlier observation that T cells from TNP-immune CBA mice stimulate optimal antibody production in culture when paired with B cells from the same individual animal. While some evidence for individual-specific T helper cells was obtained, the poorer response of mismatched T and B cells could be attributed in part to Ly-2.2-bearing suppressor T cells. Overall, the results support the view that idiotype-related regulation is not confined to dominant-idiotype models but is also involved in heterogeneous anti-hapten antibody responses.