Antigen recognition by H-2-restricted T cells. II. A tryptic ovalbumin peptide that substitutes for processed antigen

A 17-amino acid tryptic peptide of chicken ovalbumin, designated P323-339, that substituted for processed antigen when presented by glutaraldehyde prefixed accessory cells to specific I-restricted T hybridomas was characterized. The peptide antigen could not be demonstrated to have any specific or stable interactions with accessory cell Ia antigens by either direct binding or functional assays for inhibition of specific T cell activation. In addition, the T cell receptor for I-restricted antigen had no affinity for free antigen alone. A rabbit antibody specific for the antigenic peptide inhibited presentation when introduced before but not after binding of the peptide to accessory cells. These results extend our earlier finding that accessory cell-mediated processing of chicken ovalbumin can be completely explained by the fragmentation of the native molecule into smaller m.w. peptides, and suggests that if an antigen/Ia complex is important in T cell activation, it forms significantly only in the presence of the T cell receptor for I-restricted antigen.

Macrophage-dependent activation of antigen-specific T cells requires antigen and a soluble monokine

Antigen-induced T cell proliferation requires T cell interaction with antigen in the context of MHC I region-compatible accessory cells. The resulting activation and proliferation of T cells involves the production and utilization of several lymphokines or interleukins. This report describes experiments wherein these events could be separated into two phases, T cell activation and T cell proliferation. The first phase was achieved by stimulating antigen-specific T cell lines with antigen-pulsed ultraviolet light-irradiated accessory cells. T cell proliferation (second phase) could then be initiated by the addition of a soluble lymphokine with the characteristics of interleukin 1 (IL 1). These effects were only observed with homologous antigen and accessory cells syngeneic to the T cells at the I-A and E/C subregion of the MHC. This report has two applications in the study of lymphocyte-lymphokine interactions. First, T cell recognition of antigen and antigen-induced T cell proliferation can be examined as physically separate events. Secondly, this system may be used as a specific and sensitive means of measuring the effects of IL 1 on T cells.

Macrophage-dependent activation of antigen-specific T cells requires antigen and a soluble monokine

Antigen-induced T cell proliferation requires T cell interaction with antigen in the context of MHC I region-compatible accessory cells. The resulting activation and proliferation of T cells involves the production and utilization of several lymphokines or interleukins. This report describes experiments wherein these events could be separated into two phases, T cell activation and T cell proliferation. The first phase was achieved by stimulating antigen-specific T cell lines with antigen-pulsed ultraviolet light-irradiated accessory cells. T cell proliferation (second phase) could then be initiated by the addition of a soluble lymphokine with the characteristics of interleukin 1 (IL 1). These effects were only observed with homologous antigen and accessory cells syngeneic to the T cells at the I-A and E/C subregion of the MHC. This report has two applications in the study of lymphocyte-lymphokine interactions. First, T cell recognition of antigen and antigen-induced T cell proliferation can be examined as physically separate events. Secondly, this system may be used as a specific and sensitive means of measuring the effects of IL 1 on T cells.

Regulation of catabolism of IgM heavy chains in a B lymphoma cell line

The human lymphoma cell line Daudi has the phenotype of a nonsecreting B cell. This cell line synthesizes both the membrane and secreted forms of the IgM heavy chain, but only expresses functional membrane IgM. We have found that secreted type heavy chains (mus) are rapidly degraded in these cells, with a half-life of 1.3 h. Some of the membrane type heavy chains (mum) are also rapidly catabolized but some are expressed in a stable form with a half-life of 13 h. Inhibiting the initial glycosylation of heavy chains with tunicamycin has differential effects on the catabolic rates of mus and mum chains. The turnover of mus chains is not affected by this inhibitor, but the degradation of mum chains is much more rapid after tunicamycin treatment. In comparison with their glycosylated counterparts, nonglycosylated mu chains do not covalently assemble to a significant degree with light chains. Tunicamycin treatment of Daudi cells thus seems to inhibit formation of stable mum protein, possibly by altering mu chain conformation and inhibiting its interaction with light chains. We conclude from these results that some mum chains are specifically protected from proteolysis by post-translational events. These processing events include covalent assembly with light chains, terminal glycosylation, and insertion into the plasma membrane.

Antigen presentation to T cell hybridomas by a macrophage cell line: an inducible function

We have investigated the ability of an Ia-, nonantigen-presenting macrophage tumor cell line, P388D, (H-2d), to present antigen to T cell hybridomas after incubation in a lymphokine-containing preparation. P388D, cells were incubated in microtiter wells with various concentrations of Con A-stimulated spleen cell supernatants. Antigen-specific stimulation of H-2d-restricted, KLH-specific T cell hybridomas was observed by P388D1 incubated with SUP.P388D1 cells incubated for 3 days in medium or control SUP did not present antigen. In addition, no stimulation of T hybridomas was seen by P388D1 in the inhibited by the appropriate monoclonal anti-Ia reagents. These results demonstrate that a macrophage tumor cell line can be induced to present antigen and provides for large numbers of readily available, homogeneous macrophages for studying the cellular biochemical requirements for antigen processing and presentation.

Antigen presentation to T cell hybridomas by a macrophage cell line: an inducible function

We have investigated the ability of an Ia-, nonantigen-presenting macrophage tumor cell line, P388D, (H-2d), to present antigen to T cell hybridomas after incubation in a lymphokine-containing preparation. P388D, cells were incubated in microtiter wells with various concentrations of Con A-stimulated spleen cell supernatants. Antigen-specific stimulation of H-2d-restricted, KLH-specific T cell hybridomas was observed by P388D1 incubated with SUP.P388D1 cells incubated for 3 days in medium or control SUP did not present antigen. In addition, no stimulation of T hybridomas was seen by P388D1 in the inhibited by the appropriate monoclonal anti-Ia reagents. These results demonstrate that a macrophage tumor cell line can be induced to present antigen and provides for large numbers of readily available, homogeneous macrophages for studying the cellular biochemical requirements for antigen processing and presentation.

Antigen recognition by T cells. II. Intravenous administration of native or denatured ovalbumin results in tolerance to both forms of the antigen

In the accompanying report, suppressor T cells were demonstrated that did not recognize cross-reactivity between native and denatured ovalbumin (N-OVA and D-OVA). Here we show that the T cell tolerance induced by i.v. injections of antigen does detect cross-reactivity between N-OVA and D-OVA. Mice that had been immunized with either N-OVA or D-OVA in adjuvant could be rendered profoundly unresponsive if either N-OVA or D-OVA, but not an unrelated protein, were injected i.v. Cross-tolerance was observed in assays of antigen-induced T cell proliferation and helper T cell activity. Tolerance was distinguished from suppressor T cell activity by three criteria: 1) specificity for N-OVA and D-OVA, 2) sensitivity to abrogation by cyclophosphamide, 3) duration of effectiveness. These results confirm observations made by others that suggest that tolerance is mediated by an additional mechanism(s) other than suppressor T cells. Based on a hypothesis that cross-reactivity between native and denatured antigen is related to macrophage processing of antigen, these data also suggest a critical role for processed antigen in the induction of tolerance when antigen is administered i.v.

Antigen recognition by T cells. II. Intravenous administration of native or denatured ovalbumin results in tolerance to both forms of the antigen

In the accompanying report, suppressor T cells were demonstrated that did not recognize cross-reactivity between native and denatured ovalbumin (N-OVA and D-OVA). Here we show that the T cell tolerance induced by i.v. injections of antigen does detect cross-reactivity between N-OVA and D-OVA. Mice that had been immunized with either N-OVA or D-OVA in adjuvant could be rendered profoundly unresponsive if either N-OVA or D-OVA, but not an unrelated protein, were injected i.v. Cross-tolerance was observed in assays of antigen-induced T cell proliferation and helper T cell activity. Tolerance was distinguished from suppressor T cell activity by three criteria: 1) specificity for N-OVA and D-OVA, 2) sensitivity to abrogation by cyclophosphamide, 3) duration of effectiveness. These results confirm observations made by others that suggest that tolerance is mediated by an additional mechanism(s) other than suppressor T cells. Based on a hypothesis that cross-reactivity between native and denatured antigen is related to macrophage processing of antigen, these data also suggest a critical role for processed antigen in the induction of tolerance when antigen is administered i.v.

Nature of hapten-modified determinants involved in induction of T cell tolerance and suppressor T cells to NDFB contact sensitivity

Unresponsiveness to DNFB contact sensitivity induced by DNP-modified lymphoid cells (DNP-LC) is mediated by two separable pathways: a rapidly induced, long lasting inhibition of reactive T cell clones (donor tolerance), and a transient period of suppressor T cell (Ts) activity. The present report has examined the nature of the hapten-modified determinants responsible for the induction of these pathways by utilizing soluble DNP-LC cell lysate preparations as tolerogens. The results indicate that both DNP-modified MHC and non-MHC encoded determinants can mediate donor tolerance 7 days after tolerization. On the other hand, the induction of Ts requires DNP-modified MHC determinants, since DNP-LC lysates passed over lentil lectin or specific anti-H-2 immunoabsorbent columns lost their ability to induce Ts. Additional experiments showed that the injection of DNP-LC lysate compatible with the recipient strain at the H-2K and H-2D region of the MHC was sufficient for the induction of Ts. We propose that Ts induction involves the direct presentation of DNP-H-2 determinants to Ts precursors, whereas the induction of donor tolerance may involve host processing and presentation of DNP-modified membrane determinants in conjunction with host MHC structures.