Search PubMed⌕ Search

Biomedical subjects

L A Matis

Publications and source records attributed to L A Matis.

At least 91 records · Page 5Linked to original sources
PubMed1986

Expression of MEL-14 antigen is not an absolute requirement for dissemination to lymph nodes after adoptive transfer of murine T lymphocyte clones.

The inability of established antigen-specific murine T lymphocyte clones to recirculate well in vivo has been attributed to loss of the surface glycoprotein gp90MEL-14, which is important for specific adherence to post-capillary high endothelial venules in peripheral lymph nodes (LN). Defective recirculation of clones may contribute to inefficient adoptive immunotherapy when compared with fresh immune spleen or LN populations. To optimize models of adoptive immunotherapy, we sought to improve recirculation of Thy-1.2+, L3T4+ clones by inducing reexpression of MEL-14 antigen (gp90MEL-14). Clones were analyzed after treatment with differentiating agents, incubation in the presence or absence of recombinant interleukin 2 (rIL 2), coincubation in vitro with nonirradiated Thy-1.1 LN or thymus cells, or adoptive transfer into Thy-1.1 hosts. We were unable to demonstrate induction of gp90MEL-14 in any case. However, although clones remained MEL-14 negative, they were able to disseminate widely after subcutaneous adoptive transfer in the presence of clone-specific antigen and rIL 2 into Thy-1.1 mice pretreated with cyclophosphamide. Withdrawal of exogenous rIL 2 was associated with rapid disappearance of clones from all sites. We conclude that murine T cell clones undergo a step in terminal differentiation that precludes surface expression of gp90MEL-14 and that these clones would be unlikely to provide a source of long-lived recirculating memory T lymphocytes. However, under appropriate circumstances it is possible for antigen-specific clones to disseminate widely among host LN and mediate short-term immune responses.

Animals↗
PubMed1986

Adoptive immunotherapy of a syngeneic murine leukemia with a tumor-specific cytotoxic T cell clone and recombinant human interleukin 2: correlation with clonal IL 2 receptor expression.

The successful adoptive immunotherapy of the syngeneic Friend virus-induced murine leukemia FBL-3 was mediated by a proliferative MHC-restricted, tumor-specific CTL clone in combination with recombinant human IL 2. This clone was previously shown to express the L3T4-, Lyt-1+, Lyt-2+ surface phenotype. Activation of the clone for 48 hr in vitro with irradiated tumor cells induced the expression of IL 2 receptors and markedly increased clonal proliferation in response to recombinant IL 2. Intravenous injection of 2 X 10(7) 48 hr in vitro-activated cloned cells, followed by 6 days of systemic (i.p.) administration of IL 2 resulted in the complete regression of tumors and the cure of 50% of the treated mice. IL 2 alone had no effect on tumor growth, whereas the injection of nonactivated (resting) clone plus IL 2 or activated clone without IL 2 had small but insignificant effects on tumor growth and survival. These results indicated that the in vivo effector functions of cloned T cells may be markedly enhanced by the concurrent systemic administration of recombinant IL 2 and by the induction of optimal IL 2 receptor expression on the cloned T cells at the time of cell administration.

Animals↗
PubMed1986

Nodular lymphomas: current concepts.

The past several years have witnessed innovative approaches to clinical management as well as significant insights into the basic biology of the nodular lymphomas. Clinical studies have explored two apparently widely disparate approaches to the treatment of patients with nodular lymphoma. On the one hand, withholding initial therapy (watch and wait) has proved to be a viable option in the management of some patients. This approach has provided information regarding the natural history of disease, such as the relative incidence of spontaneous tumor regression vs. histologic transformation to more aggressive forms of lymphoma. Alternatively, recent data also suggest that the administration of intensive chemotherapy, shown to induce long-term remissions in a high percentage of patients with diffuse aggressive lymphomas, may also produce a significant number of durable remissions in at least certain histologic subtypes of nodular lymphomas. Clinical studies which attempt to achieve a synthesis of the above two approaches are currently in progress. Advances in immunology and molecular biology have also found application in the study of nodular lymphoma. Monoclonal antibodies have been employed diagnostically, as, for example, in detecting small numbers of persistent abnormal lymphoid clones in patients in apparent remission, and therapeutically, as exemplified by the clinical use in vivo of monoclonal antibodies directed against unique idiotypic determinants expressed by surface immunoglobulin on the malignant B lymphocytes. The demonstration of the immunoglobulin gene rearrangements in nodular lymphoma cells has established a more definitive criterion for their phenotypic characterization. Finally, molecular cloning of the breakpoint of the t(14; 18) chromosome translocation frequently found in nodular lymphoma cells has led to the identification of a potential new transforming gene which could be activated as a direct consequence of its rearrangement in proximity to the immunoglobulin in heavy chain gene locus.

Antineoplastic Agents↗
PubMed1986

Monoclonal antibody imaging of human melanoma. Radioimmunodetection by subcutaneous or systemic injection.

Fab fragments of monoclonal antibodies (MoAb) to melanoma, radiolabeled with 131I, were evaluated as diagnostic reagents to determine their ability to localize systemic--MoAb injected intravenously (IV)--or nodal metastatic disease--injected subcutaneously (SQ) at a site proximal to draining lymph nodes. Sixty-one scans were performed (40 IV, 21 SQ) in 59 patients who had injections of 0.2-50 mg of 131I coupled (0.2-12 mCi) antibody. These included 48.7, which identifies a high molecular weight antigen (HMW), or 96.5, which identifies a transferrin like molecule, p97. 125I coupled nonspecific Fab 1.4, reacting with murine leukemia virus, or the whole antibody BL3, reactive with a human B cell idiotypic determinant, was generally used in tandem with the patients injected SQ as a nonspecific control. All patients had immunohistochemical studies performed on biopsied lesions and demonstrated binding to the antibodies injected. Of the IV patients, 22/38 (58%) had (+) scans, 13 at SQ or nodal sites, four at visceral sites, and five at visceral and SQ sites. Patients with clinical stage II disease had SQ injection of MoAb, including 11 additional patients injected with the whole antibody 9.2.27 (anti-HMW) labeled with 111In (6 patients) or 131I (5 patients). Nodal dissection was performed 2-4 days later. All 111In coupled antibodies demonstrated excellent nodal delineation without specific identification of tumor deposits. Of the 21 patients injected SQ with MoAb, 17 had confirmed tumor in nodes. Of patients injected with Fab fragments, 4/8 (50%) had specific uptake of MoAb, although only two were successfully imaged. Increased uptake of antimelanoma antibodies was observed in some patients in lymph nodes not containing tumor and was possibly related to antigen shedding. Clearance of labeled antibody from the injection site occurred with a half life of 16-50 hours. Toxicity was limited to local discomfort at the site of SQ injection. Melanoma metastases can be identified with IV or SQ injection or radiolabeled antibodies. These reagents may be useful in the diagnosis or therapy of human melanoma. Further evaluation will be required before they could be considered clinically useful.

Adult↗
PubMed1985

Bone marrow-derived thymic antigen-presenting cells determine self-recognition of Ia-restricted T lymphocytes.

We previously have demonstrated that in radiation-induced bone marrow chimeras, T-cell self-Ia restriction specificity appeared to correlate with the phenotype of the bone marrow-derived antigen-presenting (or dendritic) cell in the thymus during T-cell development. However, these correlations were necessarily indirect because of the difficulty in assaying thymic function directly by adult thymus transplant, which has in the past been uniformly unsuccessful. We now report success in obtaining functional T cells from nude mice grafted with adult thymuses reduced in size by treatment of the thymus donor with anti-thymocyte globulin and cortisone. When (B10 Scn X B10.D2)F1 nude mice (I-Ab,d) are given parental B10.D2 (I-Ad) thymus grafts subcutaneously, their T cells are restricted to antigen recognition in association with I-Ad gene products but not I-Ab gene products. Furthermore, thymuses from (B10 X B10.D2)F1 (I-Ab,d)----B10 (I-Ab) chimeras transplanted 6 months or longer after radiation (a time at which antigen-presenting cell function is of donor bone marrow phenotype) into (B10 X B10.D2)F1 nude mice generate T cells restricted to antigen recognition in association with both I-Ad and I-Ab gene products. Thymuses from totally allogeneic bone marrow chimeras appear to generate T cells of bone marrow donor and thymic host restriction specificity. Thus, when thymus donors are radiation-induced bone marrow chimeras, the T-cell I-region restriction of the nude mice recipients is determined at least in part by the phenotype of the bone marrow-derived thymic antigen presenting cells or dendritic cells in the chimeric thymus.

Animals↗
PubMed1985

T cell clones to two major T cell epitopes of myoglobin: effect of I-A/I-E restriction on epitope dominance.

The murine T cell response to sperm whale myoglobin was analyzed for polyclonal and monoclonal T cells. For polyclonal T cells, the immunodominant epitope included residue Glu 109 when the antigen-presenting cells expressed I-Ad, whereas a Lys 140-containing epitope was immunodominant when the antigen-presenting cells expressed I-Ed only. Monoclonal T cells specific for each epitope were derived from a polyclonal line. T cell clones specific for the Glu 109 epitope were restricted to I-Ad, whereas the clones specific for the Lys 140 epitope were restricted to I-Ed. Thus, for an antigen that can be presented in association with either I-Ad or I-Ed, the immunodominance of particular epitopes depends strongly on the restriction element used. The immunodominance of each epitope-Ia combination may be due to a limited repertoire of T cells or selective presentation of epitope and Ia by accessory cells.

Animals↗
PubMed1985

Distinct proliferative T cell clonotypes are generated in response to a murine retrovirus-induced syngeneic T cell leukemia: viral gp70 antigen-specific MT4+ clones and Lyt-2+ cytolytic clones which recognize a tumor-specific cell surface antigen.

After immunization of B6 mice with the syngeneic retrovirus-induced T cell leukemia/lymphoma FBL-3, two major tumor-specific proliferative T cell clonotypes were derived. T cell clones derived from long-term lines propagated by in vitro culture with irradiated tumor cells and syngeneic spleen cells were exclusively of the Lyt-2+ phenotype. Such clones were cytolytic, retained their proliferative phenotype indefinitely when expanded by repeated cycles of reactivation and rest, and recognized a tumor-specific cell surface antigen in association with class I MHC molecules. This tumor cell antigen was not present on nontransformed virus-infected cells. Class II MHC-restricted MT4+ clones specific for the viral antigen gp70 were derived from lymph node T cells of FBL-3 tumor-immune mice only by in vitro culture with purified Friend virus in the presence of syngeneic splenic APC. Once derived, however, such clones could be stimulated in the presence of FBL-3 tumor cells and syngeneic spleen cells, demonstrating the reprocessing of tumor-derived gp70 antigen by APC in the spleen cell population. In contrast, no reprocessing of the tumor cell surface antigen by splenic APC for presentation to the class I MHC-restricted T cell clones could be demonstrated. Evidence is presented that FBL-3 T leukemia/lymphoma cells function as APC for Lyt-2+ class I MHC-restricted clones, and that no concomitant recognition of Ia molecules is required to activate these clones. Both Lyt-2+ and MT4+ clones were induced to proliferate in the presence of exogenous IL2 alone, but this stimulus failed to result in significant release of immune interferon. In contrast, antigen stimulation of both clones resulted in proliferation as well as significant immune interferon release. Immune interferon production is not required for the generation of MHC-restricted cell-mediated cytolytic function.

Animals↗
PubMed1985

The B10.A mouse B cell response to pigeon cytochrome c is directed against the same area of the protein that is recognized by B10.A T cells in association with the Ek beta:Ek alpha Ia molecule.

An analysis of the fine specificities of the primary and hyperimmune antibody responses of B10.A mice to pigeon cytochrome c showed that both were qualitatively very similar. Small amounts of antibody appeared to be directed against the regions of serine 15 and/or glutamic acid 44. The remaining antibodies (greater than 70%) bound to the same complex topographic determinant (including residues 3, 103, and 104) on the back surface of pigeon cytochrome c which had been found to dominate the rabbit antibody response to this protein, and to be involved in Ia-restricted T cell stimulation. The mouse antibodies reacted very poorly with fragmented forms of the immunogen or with tobacco hornworm moth cytochrome c, even though both of these antigens had been shown previously to strongly stimulate pigeon cytochrome c-primed T cells. The specificities of the primary IgG responses of seven other mouse strains were found to be very similar, but not identical, to that of B10.A mice. The cytochrome c-specific antibodies in the hyperimmune serum were shown to bind to determinants involving residues that vary between pigeon and mouse cytochromes c. Comparison of the binding of the antibodies to the immunogen and to the corresponding host protein enabled the calculation of the proportion of the overall binding energy contributed by the variant residues. This was as low as 19 to 35% for the primary response, rose to 25 to 46% for the hyperimmune mouse antibodies, and reached 40 to 63% for hyperimmune rabbit antibodies. The remaining energy of interaction (37 to 81%) was necessarily contributed by the surface of the protein surrounding the variant residues, which is the same for the immunogen and the host protein. These results illustrate the relatively subtle differences in binding affinities which can distinguish self from non-self recognition by antibody molecules.

Amino Acid Sequence↗
PubMed1984

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.

Antibodies, Monoclonal↗
PubMed1984

Self-recognition specificity expressed by T cells from nude mice. Absence of detectable Ia-restricted T cells in nude mice that do exhibit self-K/D-restricted T cell responses.

The presence in athymic nude mice of precursor T cells with self-recognition specificity for either H-2 K/D or H-2 I region determinants was investigated. Chimeras were constructed of lethally irradiated parental mice receiving a mixture of F1 nude mouse (6-8 wk old) spleen and bone marrow cells. The donor inoculum was deliberately not subjected to any T cell depletion procedure, so that any potential major histocompatibility complex-committed precursor T cells were allowed to differentiate and expand in the normal parental recipients. 3 mo after reconstitution, the chimeras were immunized with several protein antigens in complete Freund's adjuvant in the footpads and their purified draining lymph node T cells tested 10 d later for ability to recognize antigen on antigen-presenting cells of either parental haplotype. Also, their spleen and lymph node cells were tested for ability to generate a cytotoxic T lymphocyte (CTL) response to trinitrophenyl (TNP)-modified stimulator cells of either parental haplotype. It was demonstrated that T cell proliferative responses of these F1(nude)----parent chimeras were restricted solely to recognizing parental host I region determinants as self and expressed the Ir gene phenotype of the host. In contrast, CTL responses could be generated (in the presence of interleukin 2) to TNP-modified stimulator cells of either parental haplotype. Thus these results indicate that nude mice which do have CTL with self-specificity for K/D region determinants lack proliferating T cells with self-specificity for I region determinants. These results provide evidence for the concepts that development of the I region-restricted T cell repertoire is strictly an intrathymically determined event and that young nude mice lack the unique thymic elements responsible for education of I region-restricted T cells.

Animals↗
PubMed1984

Immune T cells reactive against human T-cell leukaemia/lymphoma virus.

Six patients with malignant disorders associated with human T-cell leukaemia/lymphoma virus (HTLV) were studied to see whether long-term cultures of immune T cells reactive against HTLV-infected tumour cells could be achieved. Immune T-cell lines could not be developed from the cells of five patients who died or eventually had a relapse of disease, but in one patient who had an unusually long remission of his disease after therapy, immune T-cell lines were propagated that could produce their own T-cell growth factor and proliferate upon stimulation with autologous tumour cells and also specifically lyse HTLV-infected target cells. These immune T cells recognised the presence of circulating HTLV-bearing neoplastic cells in another patient with HTLV-associated T-cell leukaemia, who had been in clinical remission after chemotherapy when this study started, thereby providing early evidence of relapse.

Cell Line↗
PubMed1984

Identification of distinct predominant epitopes recognized by myoglobin-specific T cells under the control of different Ir genes and characterization of representative T cell clones.

We characterized the fine specificity of antigen recognition of myoglobin-immune T cells from B10.D2, B10.GD, and B10.A(5R) mice. Polyclonal H-2d T cells show a predominant response to an epitope centering on Glu 109 and His 116. These residues localize a dominant epitope to one segment of the myoglobin surface, but probably are not the only amino acid residues involved. This response pattern maps genetically to I-Ad (or Kd) based on the B10.GD recombinant strain. A different epitope specificity was detected in B10.A(5R) T cells mapping to I-E beta b E alpha k or I-Cd, but no difference was detected between strains differing at the Igh locus. Thus, epitope specificity varied with Ia haplotype but not Igh allotype. Myoglobin-specific B10.D2 T cell lines were established, and five clones specific for the Glu 109, His 116 epitope were isolated; these were all restricted to I-Ad antigen-presenting cells. These clones represent the dominant specificity in the polyclonal T cell response to myoglobin and will be useful in characterizing the structure and function of T cell receptors for antigen and Ia. The differences in number and nature of T cell epitopes compared to B cell epitopes of myoglobin are discussed.

Animals↗
PubMed1983

Generation of an HLA-restricted cytotoxic T cell line reactive against cultured tumor cells from a patient infected with human T cell leukemia/lymphoma virus.

Lymphocytes from a patient who had an unusually long survival after therapy for a human T cell leukemia/lymphoma virus (HTLV)-associated T cell lymphoma were stimulated in vitro with an autologous tumor cell line, and the generation of cytotoxic T lymphocytes (CTL) was studied. CTL generated were directed against autologous (HTLV-associated tumor cells. These propagated CTL were OKT3+, OKT4-, and OKT8+. The cytotoxic activity required target tumor cells that were infected with HTLV and also expressed histocompatibility antigens in common with the patient, suggesting a major histocompatibility complex-restricted associative recognition of target antigens expressed on the tumor cell membrane.

Animals↗
PubMed1983

Magnitude of response of histocompatibility-restricted T-cell clones is a function of the product of the concentrations of antigen and Ia molecules.

The activation of specific T-cell clones by antigens is dependent upon the corecognition of restriction elements expressed on antigen-presenting cells (APC). For clones that respond by proliferation and lymphokine production, the restriction element is usually an Ia (I-region-associated) molecule. We show here that the magnitude of the proliferative response of such clones is a function of the product of antigen concentration and the number of Ia molecules expressed on APC. This conclusion was reached through the study of antigen concentration-response curves of T-cell clones specific for pigeon cytochrome c. These curves are characterized by a peak in thymidine incorporation, followed by a decrease in the magnitude of the response as antigen concentrations are increased. The decline in response at high concentrations was not the consequence of the emergence of suppressor cells in the APC population, as it was observed when cells of a cloned B-cell hybridoma line were used to present pigeon cytochrome c to these T-cell clones. The critical role of both antigen concentration and the number of Ia molecules on the APC in determining the magnitude of proliferation was demonstrated in several ways. (i) An inverse relationship was observed between the antigen concentration required for maximum proliferation and the number of APC present in culture. At high antigen concentrations, which caused responses less than maximum, reducing the number of APC actually increased the magnitude of the antigen-induced proliferation. (ii) Decreasing the number of relevant Ia molecules per APC (i.e., as in F1 hybrids) resulted in the requirement for an increased antigen concentration for maximal response and in enhanced proliferation at high antigen concentrations. (iii) In the presence of anti-Ia antibody, higher concentrations of antigen were required for maximal response; at high antigen concentrations, proliferation was enhanced in the presence of a monoclonal anti-Ia antibody directed against the Ia restriction element.

Animals↗
PubMed1983

The relationship between immune interferon production and proliferation in antigen-specific, MHC-restricted T cell lines and clones.

The release of immune or gamma interferon (IFN-gamma) by major histocompatibility complex (MHC)-restricted pigeon cytochrome c-specific Lyt 1+2-, interleukin 2 (IL 2)-producing proliferative T cell clones when cultured with antigen and antigen-presenting cells (APC) is a sensitive measure of the state of activation of the cell. In general, the fine specificity of T cell activation was similar when activation was measured either by IFN-gamma production or by proliferation. In response to antigen and the correct Ia molecule, the T cell clones produced both high titered IFN-gamma and a strong proliferative response. However, IFN-gamma production and the degree of proliferation of the T cell clones differed at high antigen concentrations. As antigen concentration increased, the magnitude of proliferation became submaximal whereas the IFN-gamma response became maximal suggesting that IFN-gamma produced by the cells might act as an autoregulatory molecule inhibiting the proliferative response. Stimulating the T cell to divide via its IL 2 receptor by adding exogenous IL 2 produced high levels of proliferation but only low titers of IFN-gamma activity. In addition, irradiation of the clone eliminated the IFN-gamma release induced by IL 2 but did not affect the IFN-gamma release induced by antigen and Ia. Thus proliferation is not essential for IFN-gamma production and unlike antigen and Ia, IL 2 functions predominantly as a proliferative signal and not as a signal for factor release. Two T cell clones showed a dissociation of IFN-gamma production and proliferation. In one case, a clone that proliferated in response to both allogeneic and antigenic stimuli released IFN-gamma in response to antigen but failed to produce IFN-gamma in response to the allogeneic stimulus. A second clone that showed a strong proliferative response to pigeon cytochrome c but no proliferative response to a species variant of cytochrome c, tobacco hornworm moth (THWM) cytochrome c, produced IFN-gamma when stimulated with either of these antigens. Thus, the sensitivity of detecting activation of T cell clones as measured by the release of an individual lymphokine varies from one clone to another.

Animals↗
PubMed1982

Contribution of antigen-presenting cell major histocompatibility complex gene products to the specificity of antigen-induced T cell activation.

Previous studies from our laboratory showed that B 10.A mice are high responders to pigeon cytochrome c fragment 81-104, whereas'B 10.A(5R) mice are low responders. In the present studies, the C-terminal cyanogen bromide cleavage fragment and homologous synthetic peptides of tobacco horn worm moth cytochrome c were shown to be immunogenic in both B10.A and B10.A(5R) mice. These strains, however, showed different patterns of cross-reactivity when immune lymph node T cells were stimulated with cytochrome c fragments from other species. To examine the two patterns of responsiveness at a clonal level, cytochrome c fragment-specific T cell hybridomas were made and found to secrete interleukin 2 in response to antigen. The patterns of cross- reactivity of these B 10.A and B 10.A(5R) clones were similar to that seen in the whole lymph node population. Surprisingly, when these clones were tested for major histocompatibility complex (MHC)-restricted antigen recognition, they were all found to respond to antigen with both B10.A and B10.A(5R) antigen-presenting cells (APC). Furthermore, the cross-reactivity pattern appeared to be largely determined by the genotype of the APC, not the genotype of the T cell clone. That is, a given T cell clone displayed a different fine specificity when assayed with B10.A or B10.A(5R) APC. This observation indicates that the APC MHC gene product and antigen interact during the stimulation of the T cell response and that as a consequence the specificity of antigen-induced T cell activation is influenced by these MHC gene products. (During the preparation of this manuscript it has come to our attention that results similar to our own, concerning the fine specificity of cytotoxic T cell clones, have been obtained by Dr. T. R. Hunig and Dr. M. J. Bevan, Massachusetts Institute of Technology, Boston, MA. T. R. Hunig and M. J. Bevan. 1981. Specificity of T-cell clones illustrates altered self hypothesis. Nature. 294:460.)

Animals↗
PubMed1982

Immune response gene function correlates with the expression of an Ia antigen. I. Preferential association of certain Ae and E alpha chains results in a quantitative deficiency in expression of an Ae:E alpha complex.

These studies were stimulated by the observation, reported in the accompanying paper (19), that IEu failed to interact with I-Ak or I-As in F1 mice to allow a response to the antigen, pigeon cytochrome c, unlike I-E subregions derived from other Ia.7+ haplotypes. Serological and biochemical analyses were performed to determine whether or not cells from these F1 mice express the Ak,se:E alpha complexes that should function as restriction elements for T cell recognition of pigeon cytochrome c on antigen-presenting cells. Using the Y-17 monoclonal antibody, which recognizes the combinatorial or conformational determinant Ia.m44 on certain Ae:E alpha complexes, we were able to distinguish between Aue:Eu alpha and Ab,k,se:Eu alpha complexes on cell surfaces. Although complement-dependent microcytotoxicity with Y-17 failed to detect Ab,k,se:Eu alpha complexes on cells from appropriate F1 mice, these molecules were detected by both quantitative absorption and quantitative immunofluorescence studies. However, Ab,k,se:Eu alpha complexes were found to be present at levels only one-seventh to one-eighth the levels expressed by homozygous I-Ab, I-Ek; I-Ak, I-Ek; and I-As, I-Ek cells. The results of two-dimensional polyacrylamide gel electrophoresis analyses suggest that the low levels of expression of Ab,k,se:Eu alpha complexes are a consequence of the preferential association of Aue and Eu alpha chains with each other in the F1 cells. As will be shown in the following paper (19), the quantitative deficiency in the expression of Ake:Eu alpha and Ase:Eu alpha complexes results in a corresponding defect in antigen-presenting cell function, thus providing strong evidence that Ia antigens represent products of Ir genes.

Animals↗