SB-restricted presentation of influenza and herpes simplex virus antigens to human T-lymphocyte clones

Detection of HLA restricted anti-minor histocompatibility antigen(s) reactive cells from skin GVHD lesions

Recipients of marrow grafts from HLA-identical, (including MLC non-reactive) sibling donors have a 40-50% incidence of acute graft vs. host disease (GVHD); the involvement of non-HLA linked, minor histocompatibility antigens (miHA) has been implicated. One of the target tissues of GVHD is the skin where morphological analysis of biopsy specimens is often used to support this diagnosis. We have obtained skin biopsy specimens from the site of GVHD lesions, grown the cells in the presence of T cell growth factor (TCGF) and feeder cells, and tested these cultured cells in the primed lymphocyte test (PLT) and cell mediated lympholysis (CML) assay. Five of six cell cultures tested demonstrated secondary proliferative but not cytolytic reactivity; cells from one culture demonstrated both reactivities. The cell culture populations generated are presumably directed against non-HLA antigens, i.e., miHA whose expression is restricted by an HLA antigen of the recipient. The data are consistent with the suggestion that in the majority of these cultures, the restriction element may be a determinant encoded within the HLA-D region: DQ, DR, and possibly DP based on panel testing. Although the number of cases is small, these preliminary data demonstrate the feasibility of this type of culturing system and also suggest that the cellular immunological events leading to the manifestation of skin GVHD lesions may be predominantly a delayed type hypersensitivity reaction.

Major histocompatibility complex restriction of tetanus toxoid-specific human T lymphocyte clones

Peripheral blood mononuclear cells (PBMC) from an HLA DRw6/7 individual were stimulated with tetanus toxoid (TT). T cell blasts were cloned by the limiting dilution technique in the presence of TT and irradiated autologous PBMC (iPBMC). Twelve were propagated under interleukin 2 and restimulated weekly with TT and iPBMC. All proliferated specifically in response to TT or either the alpha or beta chain of the toxin molecule. HLA restriction of specific proliferative responses was analyzed using a panel of HLA-typed unrelated donors and selected families, and blocking experiments with anti-HLA class I and class II monoclonal antibodies (mAb). Three types of restriction were observed: (a) autologous restriction; the inhibition observed using anti-HLA DR mAb as well as family studies performed previously with a similarly restricted clone obtained from the same donor suggest an HLA DRw6-linked restriction; (b) an HLA DR7 restriction was found for 2 clones, specific for alpha or beta chain; the identical pattern of inhibition obtained with two different mAb belonging to the same cluster suggests that these clones may be restricted by the same (or a very close) epitope of the HLA DR7 molecule; (c) an unusual restriction pattern was found for one clone; PBMC from more than 80% of donors could present TT whatever their degree of HLA compatibility with the autologous donor. Family studies were unable to disclose any restriction with known class II (or class I) antigens. While no inhibition was observed with anti-DR or -DC reagents, a mAb that recognizes class I antigen when associated with beta 2-microglobulin did inhibit the proliferation of this clone.

Role of HLA class II products in proliferative T-lymphocyte responses to PPD. Evidence of a regulatory influence associated with MB1

HLA class II determinants were analysed for their role in monocyte-T-cell interactions in the proliferative response to purified protein derivative (PPD). Allogeneic cell combinations of monocytes and T cells were tested with a range of suboptimal PPD concentrations. For each cell combination tested, a summary measure to characterize the antigen-induced response curve was calculated by means of regression analysis of the response to the dose of PPD added, thus obviating a further need to correct for mixed lymphocyte reactivity. In 200 distinct monocyte-T-cell combinations, HLA-DR appeared to be the major restricting element. Additionally, a marginal influence of HLA-MB or -MT matching was observed and no evidence of HLA-SB-restricted responses. Remarkably, the HLA-MB1 specificity was significantly associated with low responsiveness in DR sharing monocyte-T-cell combinations, indicating a modulating role of MB1 in DR-restricted T-cell responses.

Cellular basis of anti-SB response

Cloning of cells allosensitized in vitro against SB1, SB2, and SB3 antigens was performed by micromanipulation. One hundred and twenty-six clones were tested for both proliferative and cytolytic responses; 14 proliferative, noncytotoxic clones and one clone which demonstrated both proliferative and cytotoxic reactivity specific for SB antigens were obtained. The proliferative noncytotoxic clones tested and the clone with both cytotoxic and proliferative activity were all able to produce IL-2-like activity upon specific antigen stimulation in vitro and were positive for OKT3, OKT4 but negative for OKT8. The proliferative clones fit the characteristics of helper T cell (Th) clones while the clone with both cytotoxic and proliferative reactivities is analogous to the class of antigen-driven, helper cell-independent cytotoxic (HITc) clones. No cytolytic nonproliferative SB specific clones were detected. The prevalent induction of Th clones strongly suggests that the biological function of SB antigens is similar to other class II antigens of HLA. The existence of an SB specific HITc clone demonstrates that a determinant on an SB molecule can induce both proliferative and cytolytic responses.

Development and characterization of interleukin-2-independent antigen-specific human T cell clones that produce multiple lymphokines

The development of antigen-specific T lymphocyte lines and clones has greatly facilitated the investigation of T-cell recognition of and response to foreign antigens. In the present study, human antigen-specific helper T cell lines and clones which are completely independent of exogenous interleukin-2 (IL-2) have been developed by cyclic restimulation with the soluble antigen keyhole limpet hemocyanin (KLH) to which the T cell donor had previously been immunized. These T cells uniformly bear the OKT4 phenotype and were shown to require both histocompatible antigen-presenting cells (APC) and antigen for optimal proliferation. The T cell line was composed of a highly antigen-specific and clonable T cell population. Following four cycles of antigen stimulation, limiting dilution cloning analysis showed a Poisson distribution of clonable T cells with a precursor frequency of 0.62, and from 88 to 92% of viable clones were specific for the stimulating antigen. Individual clones were obtained which recognized KLH with either DR 1 (one parental Ia haplotype of the donor) or DR 2 (the other parental Ia haplotype) allogeneic APC, but not both. Following stimulation with KLH, the T cell clones produced IL-2. Peak amounts of IL-2 were assayable in the first 6 to 24 hr after stimulation. In contrast, virtually no IL-2 was detectable in supernatants at 72 to 96 hr, suggesting autoutilization by the proliferating T cells. In addition, some clones were also capable of producing both B cell growth factor and IL-2 following KLH stimulation. These IL-2-independent T cells appeared to be derived from a discrete Leu 8-negative subclass of T4+ cells and expressed the full complement of Ia antigen of the donor. Thus, soluble antigen-specific human helper T cell clones have been produced which can be maintained in the absence of exogenous IL-2, elaborate their own growth factors and other immunoregulatory lymphokines, and show fine DR-related restriction to either one or the other parental DR haplotypes in antigen-stimulated proliferative responses.

Characterization and expression of the HLA-DC antigens defined by anti-Leu 10

The expression of HLA-DC antigens on peripheral blood mononuclear cells, in tonsil and lymph node tissue sections, on tumor cell lines, and on activated T cells was studied using monoclonal antibody, anti-Leu 10. Anti-Leu 10 reacts with HLA-DC molecules on homozygous B cell lines expressing HLA-DR 1,2,4,5,6,8, and 9. It reacts with heterozygous B lymphocytes expressing DR7 and DRw10, suggesting it also recognizes HLA-DC molecules linked to DRw10. The HLA-DC molecules detected by anti-Leu 10 are expressed on all Ig-positive and DR-positive peripheral B lymphocytes and an apparent subpopulation of DR-positive peripheral blood monocytes. Two-color immunofluorescence experiments using phycoerythrin-anti-HLA-DR (L243) and FITC-anti-Leu 10 demonstrated a correlation of the amounts of HLA-DR and DC antigens expressed on B lymphocytes. Cells expressing relatively low, or high amounts of one Class II molecule express respectively low or high amounts of the other Class II molecule. Anti-Leu 10 reacted with all B lymphocyte derived tumor cell lines not with lines of myeloid or erythroid origin, and with only one T cell derived line, HUT-78 which has an activated T cell phenotype. Consistent with this result, anti-Leu 10 binding suggested the presence of HLA-DC on activated T cells in lymphoid tissue, in addition to staining B cells. HLA-DC was also detected on mitogen and MLC activated T cells by anti-Leu 10 binding. Anti-Leu 10 is, therefore, a useful reagent for further studies of the role of HLA-DC in T cell activation and in normal B cell and monocyte functions.

Clonal distribution of human T cells recognizing PPD in the context of each of two distinct Ia molecules

Participation of two of three distinct human Ia molecules, HLA-DR and the Ia molecule detected by monoclonal antibody (MoAb) 1B4 (1B4 molecules), in antigen presentation for T cell responses to purified protein derivative (PPD) and herpes simplex virus (HSV) was first suggested from studies on the inhibition of proliferative responses of whole T cell populations with MoAb against human Ia molecules. To determine whether a single T cell recognizes the antigen in the context of both Ia molecules or in the context of each one of two Ia molecules, we isolated and propagated PPD-reactive T cell clones from an HLA-DR heterozygous individual. The clones showed four different restriction patterns: type I and type II clones appeared to be restricted to one of two HLA-DR antigens, type III clones gave anomalous patterns of response and seemed to be restricted to non-DR antigens, and type IV clone recognized antigen when both DR antigens were presented on the same APC surface. Blocking study with MoAb to Ia molecules suggested that type I and type II clones are restricted to DR molecules and type III clones are restricted to 1B4 molecules distinct from DR or MB1 molecules. Furthermore, it is most likely that type IV clone was restricted to the interaction molecule associated with DR antigens. These data imply that human T cell clones recognizing PPD in the context of each one of two Ia molecules are clonally distinct.

Antigen-specific proliferative human T cell clones with specificity for diphtheria toxoid: genetic and molecular restriction by class II antigens

Human T lymphocyte clones (TLC) specific for diphtheria toxoid (DT) were isolated from a DR6/7 individual by cloning in soft agar in vivo sensitized T lymphocytes. We report here the isolation and characterization of 3 of these clones by studying: (a) the kinetic of activation, (b) the surface phenotypes, (c) the fine specificity for one of the 2 DT chains and (d) the genetic restriction of the proliferative response by the haplotype DR7. Moreover, blocking studies of the proliferative response to DT by various immunochemically characterized anti-HLA-DR monoclonal antibodies indicate that, on the DR7 molecule, more than one Ia determinant may participate in the clonal DT proliferative response. By using human TLC of a defined specificity and well-characterized anti-DR monoclonal antibodies, such studies may help to define the functional repertoire of Ia molecules in man.

Molecular organization of the HLA-SB region of the human major histocompatibility complex and evidence for two SB beta-chain genes

The class II products of the major histocompatibility complex, also called Ia antigens, are composed of two polypeptide chains, the alpha and beta chains, both encoded within the major histocompatibility complex. In man, the class II antigens can be divided into three biochemically distinct groups called HLA-DR, HLA-DC, and HLA-SB. Our isolation of cDNA clones for the polymorphic beta chain of HLA-DR and HLA-DC has allowed us to study the organization of the class II genes. Here we identify the HLA-SB beta-chain gene in recombinant clones from a cosmid library generated from a consanguineous homozygous B-cell line. The SB beta-chain gene is linked to the SB alpha-chain gene and the two genes are in opposite orientation. A second SB beta-chain gene, corresponding to a new SB beta II locus, has also been identified and cloned. The SB beta-chain genes show much less allelic restriction site polymorphism than the genes for the beta chains of HLA-DR or HLA-DC.

Antigen-specific suppression of human antibody responses by allogeneic T cells. I. Frequency and antigen specificity of allogeneic suppressor T cells and their role in major histocompatibility complex-controlled genetic restriction

Specific antibody responses to influenza virus were obtained in vitro from human blood mononuclear cells (PBM). The addition of allogeneic T cells to responding PBM profoundly suppressed antigen-induced antibody responses, but had no effect on pokeweed mitogen (PWM)-induced polyclonal Ig formation. This raised the possibility that suppression by allogeneic T cells may result from the activation of antigen-specific T suppressor (Ts) cells rather than nonspecific allogeneic effects. The frequency of allogeneic Ts in PBM from a number of different donors, estimated in a series of limiting dilution analyses, was found to range from 0.8 X 10(-5) to 4.5 X 10(-5), which is more typical of antigen-specific than alloreactive T cells. By adding limiting numbers of allogeneic T cells to antibody-forming cultures stimulated simultaneously with two non-cross-reacting antigens (influenza A and B strain viruses A/X31 and B/HK), it was possible to demonstrate suppression of the response to one antigen, but not the other, in the same culture well. Moreover, the frequency of wells in which the response to both antigens was suppressed was not significantly different from that predicted from the calculated frequency of specific allogeneic Ts. These results show that allogeneic suppression was antigen specific, and was not due to non-specific allogeneic effects. By separating T cell preparations into Leu-3a+ (helper) and Leu-2a+ (suppressor/cytotoxic) T cell subsets, suppression was shown to be mediated by a radiosensitive Leu-2a+ T cell. The removal of Leu-2a+ cells from T cell preparations abrogated the suppressor effect and permitted T cell collaboration with B cells, across an HLA-A, -B, and -DR barrier. This result shows that in at least some combinations, suppression rather than major histocompatibility complex restriction is the reason for the failure of allogeneic T and B cells to collaborate in T cell-dependent antibody responses.

Cloned human T lymphocytes with lymphostimulatory capacity preferentially activate suppressor cells

A proportion of cloned T cells derived from allogeneic mixed leukocyte cultures (MLC) was found to stimulate rapid primary, but not secondary, lymphoproliferative responses of autologous as well as allogeneic peripheral blood mononuclear cells (PBMC). Of eight major histocompatibility complex (MHC) class II-specific monoclonal antibodies (mAb), the reagent TU39 (which preferentially inhibits allostimulation by SB- rather than DR- or DC-associated determinants) most strongly inhibited stimulation by these clones. MAb specific for DC or DR molecules inhibited weakly or not at all. Stimulatory, but not nonstimulatory, clones were found to be strongly suppressive when titrated directly into MLC. Suppression was no MHC restricted, was radioresistant (20 Gy) and was not abrogated by the addition of partially purified interleukin 2 to the test cultures. Transfer of PBMC cocultured with stimulatory, but not with nonstimulatory, clones into a second MLC resulted in its strong suppression, suggesting that a suppressor effector population had been "induced" by the clones. These results are consistent with the hypothesis that SB-like, rather than DR or DC, determinants present on the surface of certain activated T cells are intimately involved in the regulation of cellular immune responses by rapidly inducing suppressor effector cells in normal lymphocyte populations.

Essential requirement for major histocompatibility complex recognition in T-cell tolerance induction

The induction of T-cell responses involves the recognition of extrinsic antigen in association with antigens of the major histocompatibility complex (MHC), in mice and man, with different T cells recognizing antigen in association with either class I (H-2K/D, HLA-A, B, C) or class II (Ia, HLA-D/DR) MHC antigens. However, the requirement of MHC recognition in the induction of immunological tolerance remains ill defined. With human T helper clones recognizing synthetic peptides of influenza haemagglutinin (HA-1), we have investigated the nature of antigen-induced stimulation, and antigen-induced antigen-specific unresponsiveness, immunological tolerance. Tolerance is not due to cell death, as the cells remain responsive to interleukin-2 and is associated with the loss of T3 antigen from the cell surface. Using monoclonal antibodies to the non-polymorphic regions of human class II antigens to inhibit the induction of T-cell tolerance we report here that induction of tolerance requires the recognition of MHC antigens.

Strong lymphoproliferative suppressive function of PLT clones specific for SB-like antigens

From a total of 37 different priming combinations between donors matched for HLA-A,B, and/or Dw/DR, but mismatched for SB, antigens, T cell clones strongly restimulated with concordance for SB specificities were isolated from only two. Most of the alloproliferative (PLT) clones obtained were restimulated by determinants not correlated with any currently known HLA product. Nonetheless, their stimulation was inhibited by a monoclonal antibody TU 39, which preferentially blocks stimulation by SB-, rather than by Dw/DR-associated determinants. Despite having an OKT4+, OKT-, Leu8- phenotype, and secreting Interleukin-2 after contact with stimulatory cells, these clones strongly suppressed proliferative responses of cloned PLT reagents as well as unprimed lymphocytes in mixed leukocyte cultures. They may thus represent a novel type of immunoregulatory T cell, stimulated by SB-related antigens, which despite their "helper/inducer" phenotype are able directly to suppress lymphoproliferative responses.

Influenza A hemagglutinin-specific T cell clones strictly restricted by HLA-DR1 or HLA-DR7 molecules

The antigenic specificities, major histocompatibility complex restrictions and functional properties of influenza virus-specific proliferative cloned cell lines have been studied. These lines were specific for the H3 hemagglutinin subtype of influenza A viruses. By using a large panel of HLA-phenotyped antigen-presenting cells, it was found that the polymorphic structures, defined as DR1 and DR7 molecules, or closely associated structures, function as the restricting elements. We excluded for these lines a possible restricting role of supertypic specificities, known cross-reacting elements on DR molecules, or products of other loci in known linkage disequilibrium with the HLA-DR molecules. Such exquisitely restricted clones might be of great help in the class II typing of antigen-presenting cells. Their specific activity was stable for several months. This has allowed the study of some functional properties of these long-term-cultured cloned cell lines: interleukin 2 sensitivity and production, helper function in specific antibody synthesis and ability to stimulate in mixed leukocyte reactions.

Antigen-specific HLA-restricted human T-cell lines. I. An MT3-like restriction determinant distinct from HLA-DR

The results presented provide evidence that the HLA specificity known as MT3, BR4, or Hon7 can serve as a restriction epitope for the proliferation of certain T cells responding to mumps viral antigen. This restriction determinant was found to be HLA-linked in family studies, and to segregate centromeric to a crossover between HLA-B and DR in one family. In the population studied, the specificity was found to be associated with the DR antigens DR4, DR7, and DRw9, which are known to be associated with MT3. The ability of accessory cells to present mumps antigen in the context of this supertypic restriction determinant was blocked by a monoclonal antibody specific for MT3. Since MT3 (BR4, Hon7) has been shown to be expressed on molecules distinct from DR, our experiments suggest that such molecules are functionally important in antigen presentation to T cells.

Restriction molecules involved in the interaction of human T cell clones with antigen-presenting cells

Two of three distinct human Ia molecules detected by murine monoclonal antibodies (MoAb) have been suggested to be involved in antigen presentation for T cell responses to purified protein derivatives (PPD) and herpes simplex virus (HSV). This observation was first suggested from studies on the inhibition of proliferative responses of whole T cell populations with MoAb against human Ia molecules. To determine whether a single T cell recognizes the antigen in the context of both Ia molecules or in the context of each one of two Ia molecules, we isolated and propagated PPD-reactive T cell clones from an HLA-DR heterozygous individual. They showed four different restriction patterns: type I and type II clones each appeared to be restricted to one of two HLA-DR antigens, type III clone gave anomalous patterns of response and seemed to be restricted to non-DR antigens, and type IV clone recognized antigen when both DR antigens were presented on the same antigen-presenting cells (APC) surface. Blocking study with monoclonal anti-Ia antibodies suggested that type I, II and IV clones are restricted to DR molecules and type III clones are restricted to 1B4 molecules distinct from DR or MB1 molecules. These data imply that human T cell clones recognizing PPD in the context of each one of two Ia molecules are clonally distributed.

Antigen-specific HLA-restricted human T-cell lines. II. A GAT-specific T-cell line restricted by a determinant carried by an HLA-DQ molecule

Human T-cell lines responsive to the polypeptide antigens GAT and (T,G)-A--L were developed. They were specific for the priming antigens and required the participation of accessory cells matched for HLA-linked determinants, as shown in family studies. In panel studies, the ability of accessory cells to present antigen was shown to be associated with HLA-D-region antigens. However, the specificity of these determinants did not fully correspond to any HLA antigens as currently defined. One GAT-specific subline, derived by limiting dilution, utilized a restriction determinant associated with, but distinct from, the DQw3 (MB3) allospecificity. Blocking studies with mouse monoclonal antibodies indicated that this restriction determinant was carried by HLA-DQ molecules. The epitopes recognized in these molecules appear to be distinct from the alloantigenic determinants currently defined by serology.

Human helper T-cell clones that recognize different influenza hemagglutinin determinants are restricted by different HLA-D region epitopes

Human T-lymphocyte clones ( TLCs ) were generated against the hemagglutinin (HA) of A/Texas/1/77 influenza virus by limiting dilution. TLCs were then screened for antigen specificity on chemically synthesized peptides representing the HA1 molecule. It has been hypothesized that different T cells that recognize the identical antigenic determinant are controlled by (restricted by) the same class II epitope. Two TLCs , HA1.4 and HA1.7, both recognized the same HA peptide and in proliferation studies exhibited identical restriction patterns. Two other clones, HA 1.9 and HA 2.43, recognized different HA determinants and also had distinct restriction patterns. Proliferation inhibition studies with monoclonal antibodies against human class II molecules demonstrated three unique patterns of blocking with the clones, suggesting that clones may be restricted to a unique class II epitope depending on the HA determinant recognized. These data can be interpreted as supporting the argument that human immune responses to influenza hemagglutinin are under Ir gene control exerted at the level of the viral antigenic determinant recognized in association with particular D-region restricting elements. The determinant selection and clonal deletion theories are compared for their capacity to best explain these findings.

EBV transformed B cell lines present to antigen specific T cell clones determinants different from those recognized by antibody in an HLA-DR linked restricted fashion

Human B cells nonspecifically activated by Epstein Barr virus (EBV) can present tetanus toxoid (TT) antigen to TT specific helper T cell lines and T cell clones. Presentation of TT antigen by EBV-B cells did not require the presence of TT specific B cells and did not involve B cell surface immunoglobulins. Immunosorbent purified antibody to TT added in great excess to EBV-B cells pulsed with TT for 18 hr did not inhibit the capacity of the EBV-B cells to present TT antigen. Furthermore, EBV-B cells induced proliferation in T cells in the presence of urea denatured TT which contained less than 1% TT reactive with serum anti TT antibody. Studies of TT presentation by a panel of EBV-B cells obtained from HLA typed donors indicated that T cell recognition of TT presented by EBV-B cells was MHC restricted by products of the HLA-D region and some of which differed from serologically defined HLA-DR. These results indicate that the immunogenic moiety presented by EBV activated human B cells consists of antigenic determinants, which differ from those recognized by serum antibody, and of HLA-DR linked MHC determinants. This moiety is similar to that presented by monocytes. The implications of these findings for the amplification of the immune response by activated B cells are discussed.

Class-II HLA restriction of antigen-specific human T-lymphocyte clones. Evidence of restriction elements on both DR and MT molecules

Blast-enriched suspensions of T cells primed for Chlamydia trachomatis antigen were cloned by a limiting dilution technique. The class-II HLA restriction of T-lymphocyte clones (TLC) was studied by using allogeneic antigen-presenting cells (APC) carrying foreign class-II HLA antigens. Most of the TLC were restricted by one or the other of the D/DR determinants of the T-cell donor; that is, they did not respond when antigen was presented by APC expressing foreign D/DR determinants. Furthermore, heterogeneity of the DR4-expressing molecule could be demonstrated by T-cell clones from one person; APC from family members expressing DR4 gave high proliferative responses, whereas no proliferation was observed with most APC from unrelated persons expressing DR4. This heterogeneity of DR4 was confirmed by mixed lymphocyte culture (MLC) experiments, indicating a close relationship between restriction epitopes and those that activate allogeneic T cells. Other clones seemed to be restricted by other class-II HLA determinants, most probably MT determinants of the T-cell donor. The restriction specificities were confirmed by subcloning experiments.

Identification of four SB antigens by cloned cells. Population studies of Norwegians

By priming in vitro with allogeneic HLA-DR compatible and also HLA-A,B mostly compatible lymphoid cells, PLT cells resulted in recognizing a group of non D/DR allelic antigens provisionally named K, L, M and N. To improve discrimination these bulk primed typing reagents were cloned and expanded. By typing of previously SB typed lymphoblastoid B cell lines (LCL) the provisional specificities could be identified as SB1, 4, 3 and 2, respectively. Typing of 186 unrelated Norwegians gave the following gene frequences: SB1: 0.05, SB2: 0.16, SB3: 0.13, SB4: 0.42 and SB blank: 0.24. No triplets were found, the calculated gene frequencies fit with Hardy-Weinberg equilibrium, and typing of a B-DR recombinant family confirmed that the SB locus is situated centromeric to B. Associations between SB and A, B, DR antigens in the same material were generally weak, the most significant associations found were between SB1-DR3 and SB4-DR2.