Expression Of Ia-like Antigens Research Articles

Increased percentage of activated Ia + T lymphocytes in peripheral blood of neonates following exchange blood transfusion

The expression of Ia-like antigens in peripheral blood T lymphocytes from newborns receiving postnatal total blood exchange was analyzed. A significantly increased percentage of Ia-positive T lymphocytes (Ia + T cells) was observed 2 days after postnatal transfusion with total blood in comparison to data observed on Days 0, 5, and 15. Ia + T cells were also significantly higher than in normal control newborns tested in the same period. When newborns received the blood exchange with irradiated total blood or with leukocyte-depleted blood, no increase in Ia + T cells was observed and the percentage of these cells remained in the normal range (1–7%) on all the days tested (0, 2, 5, 15 days). For easy identification of the origin of Ia + T cells, sex-incompatible blood was used for exchange, and a karyotype analysis was carried out for the detection of the Y chromosome on Ia + T cells separated from peripheral blood on Day 2 and then cultured with interleukin 2 (IL-2) for 48 hr. It was thus established that Ia + T cells were not of donor origin. Simultaneously with the expression of Ia-like antigens, host T cells also carried the interleukin-2 receptor (TAC). An allogeneic response, comparable to a host-versusgraft reaction, was probably responsible for the activation of T cells 2 days after total blood exchange in newborns.

Peripheral blood T lymphocytes of patients with chronic B cell lymphatic leukemia express Ia-like antigens

15.7 +/- 3.5% of sheep rosette-forming cells (SRFC) were isolated from the peripheral blood of 11 patients with B-cell chronic lympholeukemia (B-CLL). SRFC did not express surface immunoglobulins, antigens of nondifferentiated blasts and antigens of early T-cell precursors, while NK-cell antigen expression was low. 6 of 11 patients revealed 44.6 +/- 19.6% of Ia-like antigens in SRFC. Ia-like antigen expression was 4.8 +/- 0.6% in SRFC isolated from the peripheral blood of 19 healthy donors. The expression of Ia-like antigens in T cells of patients with B-CLL is suggested to be related to the activation of regulatory T-lymphocyte subpopulation.

Enhancement of Ia-like antigen expression by interferon-gamma in polymorphonuclear leukocytes.

The effects of interferons (IFNs) on Ia-like antigen expression in human peripheral blood polymorphonuclear leukocytes (PMNs) were examined in vitro using flow cytometry and FITC-labelled monoclonal antibody specific for the Ia-like antigen OKIa1. Recombinant human IFN-gamma markedly enhanced the expression of Ia-like antigen on PMNs and increased the number of Ia-positive PMNs. In contrast, natural human IFN-alpha and-beta had no effect on the expression when compared on the basis of antiviral activity.

Aberrant expression of Ia-like antigens on tumor cells of regressing but not of progressing Rous sarcomas.

Unlike many other tumors, experimentally induced Rous sarcomas in chickens have a definite tendency to regress spontaneously. Regression is under genetic control, but it is immunologically mediated although the target antigens that stimulate an immune response are unknown. Tumor cells in regressing sarcomas were found to express class II major histocompatibility complex (Ia-like) antigens while tumor cells from progressing sarcomas were negative. This suggests that the induction of Ia-like antigen expression has a role in the initiation or perpetuation of regression, similar to that postulated for class II antigen expression in a variety of autoimmune diseases.

HLA antigens on human hemopoietic progenitors during embryonic-fetal life: Expression and in vitro modulation

We have analyzed the time course of the expression of HLA antigens on hemopoietic progenitors (BFU-E, CFU-E and CFU-GM) from human embryonic-fetal livers (FL). HLA ABC and Ia-like antigens are never detected on progenitor cells at 5-week post-conception. Their expression initiates at 6-week and progressively increases thereafter, up to near-adult levels at 9-week. The time course of HLA antigen expression on erythroid precursors, derived from FL at corresponding gestational ages, parallels that observed on hemopoietic progenitors. Incubation of embryonic progenitors or precursors with medium conditioned by PHA-stimulated adult peripheral blood mononucleated cells induces a marked increase of the expression of both HLA-ABC and Ia-like antigens. Conversely, incubation with recombinant γ- interferon causes amarked increase of HLA-ABC but not Ia-like antigen expression, thus in contrast with results observed on adult monocytes.

Heterogeneity of Ia antigen expression on myeloblastic leukaemias: correlation with stage of maturation defined by cytochemical markers.

The expression of Ia-like antigen (Ia) has been studied in 55 cases of acute myeloid leukaemia (AML) in correlation with the expression of both Sudan Black (SB) and naphthol AS-D chloroacetate esterase (NCAE) stains. Operationally the AML cases were divided into three groups using only NCAE expression on the leukaemic cells: the first group with early maturation stage (MS1) consisted of 30 cases with less than 10% NCAE positive cells (SB: 15-100%): the MS2 group of 14 cases with 10-70% NCAE positive cells (SB: 65-100%) and the MS3 group of 11 cases with 70-100% NCAE positive cells (SB: 89-100%). Ia expression was determined by complement-dependent cytotoxicity, immunofluorescence and immunoperoxidase methods. A similar high percentage (80%) of patients from both group MS1 and MS2 expressed Ia on the surface of 32-100% of the cells. Furthermore, individual comparison of all cases from these two groups showed no correlation between Ia, NCAE and SB expression. Only in the 11 cases from the MS3 group, which included nine cases of promyelocytic leukaemias, was there a correlation between very low expression of Ia antigen with the high NCAE expression. Thus, for AML with a low degree of differentiation the expression of Ia seems to be independent of conventional cytochemical markers of cell maturation.

Ia-like antigen expression on biologically different human melanoma cell lines

Ia-like antigen binding of a large panel of monoclonal antibodies (six anti-human Ia-like monoclonal antibodies and ten murine anti-Ia monoclonal antibodies cross-reactive with human Ia-like antigens) were compared on seven permanent human melanoma cell lines by radioimmunoassay. Cell lines were initiated from primary or metastatic tumors and presented various levels of tumorigenicity (assessed by heterotransplantation in nude mice) and pigmentation (shown by 5-S-cysteinyldopa determination and cytological data). Two cell lines originated from the same primary melanoma, while two other pairs of cell lines originated from superficial spreading melanoma or metastatic lymph node of the same patients. Identical Ia-like allodeterminants were found in cell lines of the same individual origin. Quantitative expression of β 2-microglobulin and Ia-like antigens was similar in all cell lines except for one, in which these molecules were expressed in lower amounts. These results indicate that Ia-like antigen expression of the cell lines is unrelated to primary or metastatic origin, degree of pigmentation and ability to grow in nude mice.

Phenotyping of canine lymphoma with monoclonal antibodies directed at cell surface antigens: classification, morphology, clinical presentation and response to chemotherapy.

Forty cases of naturally occurring canine lymphoma were studied using a panel of murine monoclonal antibodies which identify defined subsets of normal canine lymphocytes. The distribution of phenotypes was similar to that which is seen in man in that the majority (78 per cent) of canine lymphomas were of B-cell origin but a definite minority were phenotypically of T-cell (10 per cent) or non-B, non-T-cell (12 per cent) origin. The expression of Ia-like antigens was restricted to B-cell neoplasms. Within each histologic subgroup of canine lymphomas there was considerable heterogeneity of cell surface marker expression. Immunophenotype appeared to correlate with clinical presentation. Finally, the reactivity of lymphoma cells with murine monoclonal antibody DLy-6, an antibody which appears to react with a differentiation antigen on canine B and T cells, strongly predicted the outcome of initial induction chemotherapy in that all ten evaluable dogs with DLy-6-tumors achieved complete responses to initial chemotherapy while only four of 11 dogs with DLy-6+ tumors responded completely.

Antigenic profile of human melanoma cells. Analysis with monoclonal antibodies to histocompatibility antigens and to melanoma-associated antigens.

Antigenic profile of human melanoma cells. Analysis with monoclonal antibodies to histocompatibility antigens and to melanoma-associated antigens.

Expression of Ia-like antigens by human vascular endothelial cells is inducible in vitro: demonstration by monoclonal antibody binding and immunoprecipitation.

The expression of Ia-like antigens by cultured human endothelial cells has been investigated by means of monoclonal antibody binding to intact cells and by immunoprecipitation of radioiodinated membrane proteins. Primary growing and confluent cultures of human umbilical vein endothelium express little, if any, detectable Ia-like antigens under standard culture conditions. However, treatment of primary cultures with the lectin phytohemagglutinin induces the expression of Ia-like antigens. This action of the lectin uniformly affects all the endothelial cells in a culture, does not depend on cell division, and is associated with a cell shape change. The data presented in this report provide unequivocal serological and biochemical demonstration of Ia-like antigens on human vascular endothelial cells. The fact that the expression of Ia-like antigens by endothelium can be induced may have important implications for organ transplantation and for regulation of the immunological response.

Expression of Ia-like antigens defined by monoclonal OKIal antibody of hemopoietic progenitor cells in cord blood: a comparison with human bone marrow

Expression of Ia antigens on granulocyte/macrophage colony-forming cells (CFU-GM) in human cord blood was compared with that in bone marrow with the use of monoclonal OKIal antibody. Mononuclear cells prepared from cord blood and bone marrow were pretreated with OKIal antibody plus complement, and, thereafter, the ability of cord blood and bone marrow cells to form colonies of CFU-GM was assayed in semisolid agar culture. Consistent reduction in the number of CFU-GM in cord blood to 58.8% +/- 13.0% (mean +/- SD) of controls treated with complement alone was shown after elimination of Ia-antigen-bearing CFU- GM, but was significantly remarkable than that in bone marrow (18.0% +/- 5.6%). Although the reduction of both granulocyte (CFC-G) and macrophage colony (CFC-M) types of cord blood, characterized by the double staining for esterase activity, was shown following treatment with OKIal antibody plus complement, the relative inhibition of CFC-G weas significantly greater than that of CFC-M (p less than 0.02). These results suggest some differences in the characteristics of Ia-antigen- bearing CFU-GM between cord blood and bone marrow cells. Furthermore, it is suggested that Ia-dependent regulatory mechanisms might participate in the differentiation of CFU-GM to CFC-G and CFC-M.

Expression of Ia-Like Antigens Defined by Monoclonal OKIal Antibody on Hemopoietic Progenitor Cells in Cord Blood: A Comparison With Human Bone Marrow

Expression of Ia antigens on granulocyte/macrophage colony-forming cells (CFU-GM) in human cord blood was compared with that in bone marrow with the use of monoclonal OKIal antibody. Mononuclear cells prepared from cord blood and bone marrow were pretreated with OKIal antibody plus complement, and, thereafter, the ability of cord blood and bone marrow cells to form colonies of CFU-GM was assayed in semisolid agar culture. Consistent reduction in the number of CFU-GM in cord blood to 58.8% +/- 13.0% (mean +/- SD) of controls treated with complement alone was shown after elimination of Ia-antigen-bearing CFU-GM, but was significantly remarkable than that in bone marrow (18.0% +/- 5.6%). Although the reduction of both granulocyte (CFC-G) and macrophage colony (CFC-M) types of cord blood, characterized by the double staining for esterase activity, was shown following treatment with OKIal antibody plus complement, the relative inhibition of CFC-G weas significantly greater than that of CFC-M (p less than 0.02). These results suggest some differences in the characteristics of Ia-antigen-bearing CFU-GM between cord blood and bone marrow cells. Furthermore, it is suggested that Ia-dependent regulatory mechanisms might participate in the differentiation of CFU-GM to CFC-G and CFC-M.

Association between colony forming units-granulocyte macrophage expression of Ia-like (HLA-DR) antigen and control of granulocyte and macrophage production. A new role for prostaglandin E.

The expression of Ia-like antigens on human colony forming units-granulocyte macrophage (CFU-GM) is related to S-phase of the cell cycle, and associated with the control of normal granulocyte and macrophage production by prostaglandin E and acidic isoferritins in vitro. Ia-antigen expression by CFU-GM is lost within 3-6 h of culture at 37 degrees C and occurs simultaneously with loss of responsiveness to inhibition by these factors. Culture of bone marrow CFU-GM in a limited exposure suspension culture with 1 microM-1pM prostaglandin E (PGE1 or PGE2), but not prostaglandin F2 alpha or dibutyryl-cyclic-3'-5'-AMP results in the detection of CFU-GM Ia-antigen after 24 h. Antigen expression is associated with an absolute increase in total and S-phase CFU-GM, and restoration of responsiveness to inhibition by prostaglandin E and acidic isoferritins. The detection of Ia-antigen on CFU-GM after suspension culture with prostaglandin E results both from Ia-antigen reexpression as well as stimulation of noncycling cells to enter S-phase, express Ia-antigen and give rise to CFU-GM sensitive to inhibition by prostaglandin E and acidic isoferritins. The sensitivity of CFU-GM to inhibition by these factors after suspension culture with prostaglandin E is identical to that of the same cells tested prior to the suspension culture. These studies provide evidence for a direct regulatory association between Ia-antigen expression and control of myeloid progenitor cell differentiation, and suggest a role for prostaglandin E in the control of CFU-GM cell cycle, Ia-antigen expression, and growth regulation.

Modulation of Tac antigen on activated human T cells by anti-Tac monoclonal antibody.

A monoclonal antibody termed anti-Tac antibody is reactive with activated and functionally mature human T cells, but not reactive with resting T cells or B cells. We found that the expression of Tac antigen on activated T cells was inhibited by the addition of anti-Tac antibody in the culture of T cells activated with Con A or alloantigen. In the mixed lymphocyte culture, the expression of Ia-like antigen on allo-activated T cells was also inhibited by anti-Tac antibody, although the antibody does not recognize Ia-like antigen. However, anti-Ia monoclonal antibody did not suppress the expression of either Tac or Ia-like antigen. In addition, Tac antigen expressed on activated T cells was modulated by anti-Tac antibody cultured with activated T cells at 37 degrees C for 48 hr. Antigenic modulation, which means a specific loss of Tac antigen from the cell surface of T cells, was detected by the indirect immunofluorescence method. Tac antigen was reexpressed on T cells after restimulation when the anti-Tac antibody was removed, whereas Ia-like antigen already expressed on allo-activated T cells was not modulated by anti-Tac antibody. These results suggest that Tac and Ia-like antigens are carried on different molecules, both of which are closely linked in expression on activated T cells. The expression of Tac antigen may be essential for the following expression of Ia-like antigen.

Self-assessment

The distribution of Ia-like antigens in human kidney has been investigated by indirect immunofluorescence staining of frozen sections with monoclonal antibodies to framework determinants of Ia-like antigens. These antigens are localized by patchy and interrupted linear fluorescence along the endothelium of glomerular efferent arterioles and capillaries, intertubular cortical and medullary capillaries as well as the vasa recta. Ia-like antigens are undetectable, however, on the endothelia of arcuate and interlobular arteries and on tubular epithelial cells. The expression of Ia-like antigens on kidney endothelial cells may account for the role of Ia-like antigens in kidney allograft rejection.

A radioimmunoassay and biological profile of Ia-like antigens on human melanoma cells

Human melanoma cells have unexpectedly been found to express Ia-like antigens, histocompatibility type antigens which are believed to be the gene products of the immune response region. Melanoma derived Ia-like antigens are immunologically functional. Monoclonal antibodies have been produced to these antigens. The level of Ia-like antigens on melanoma cells is significantly lower than on B lymphoid cells, and this is more likely to reflect a reduced synthesis than an increased shedding. We have employed radioimmunometric and immunofluorescent procedures in this investigation, Melanoma cell-derived Ia-like antigens have a structure similar to that of B lymphoid cell-derived Ia-like antigens. The antigens are composed of two non covalently associated glycoproteins. One chain, referred to as the alpha chain, has an approximate molecular weight of 34,000 and the other one, referred to as the beta chain, has an approximate molecular weight of 29,000. The expression of Ia-like antigens is restricted to malignant melanoma and not on benign nevi.

Changes in Ia-like antigen expression on malignant human cells

In human and in animal model tumor systems malignant cells may express allospecificities or types of histocompatibility antigens that are not detectable on their normal counterparts (Invernizzi and Parmiani 1975, Garrido et al. 1976, Pellegrino et al. 1976, Martin et al. 1977, Winchester et al. 1978, Wilson et al. 1979 a). Among them the appearance of Ia-like antigens on human melanoma cells (Winchester et al. 1978, Wilson et al. 1979 a) is of particular interest because of the possible role of these antigens in the interaction between host's immune system and tumor cells (Forni et al. 1975). In view of this finding we have investigated whether variations in expression of Ia-like antigens occur in other human tumors of nonlymphoid origin by testing surgically removed tumor specimens with monoclonal antibodies to Ia-like antigens in indirect immunofluorescence (IIF). Monoclonal antibodies Q 5/13 (MoAb Q S/13) to framework determinants of Ialike antigens were prepared and characterized as described (Quaranta et al. 1980). Tumor specimens, which were obtained from patients undergoing surgery in the Regina Elena Cancer Institute, Surgery Division, were immediately frozen in liquid nitrogen. Two consecutive 4 g cryostat sections from each tumor sample were fixed for 5 minutes in absolute acetone, which was shown by preliminary experiments not to effect the antigenicity of Ia-like antigens in tissue. One section was stained with Toluidine blue (0.1~o in phosphate-buffered saline) and the other was used as substrate in an IIF test with the anti-Ia-like antigen MoAb Q5/13 with an average concentration of 5 gg/ml and a fluorescein labeled (FITC) rabbit anti-mouse Ig antiserum (Meloy Laboratories, Springfield, Virginia) as second antibody. The FITC anti-mouse Ig xenoantiserum, which had fluorescein/protein ration of 3 and a protein concentration of 1.5 mg/ml, was preabsorbed with ABRH + red blood cells and with peripheral blood lymphocytes (PBL) of chronic lymphocytic leukemia (CLL) patients, which express high levels of Ia-like antigens. The specificity of the strain observed on different tumor-tissue substrates was assessed by direct staining with the FITC-labeled antiserum and by indirect staining with MoAb Q5/13 preabsorbed extensively with an equal volume of PBL from CLL patients or

Modulation of Ia-like antigen expression and antigen-presenting activity of human monocytes by endotoxin and zymosan A.

The environmental agents E. coli endotoxin and zymosan A modulated antigen-specific T cell proliferation in vitro, assessed by 3H-TdR uptake. In the continual presence of these agents, human mononuclear leukocyte responses to the antigens tuberculin PPD, Candida albicans, and mumps were significantly reduced. Treatment of adherent cell-depleted T cells with the agents did not affect their subsequent reactivity to soluble antigens in the presence of normal M phi. However, cultures consisting of pretreated M phi, normal T cells, and soluble antigen gave responses that were only 7 to 38% of control values, indicating that the function of the antigen-presenting cell, not the T cell, was inhibited. This effect was observed only when treatment with endotoxin or zymosan A preceded antigen stimulation by at least 24 hr, suggesting that a gradual inhibition of antigen presentation had occurred. When various ratios of normal antigen-pulsed and agent-treated M phi were cultured with normal T cells, antigen-specific responses were not significantly different from control cultures; this indicated that M phi-mediated suppression was not involved. It did not appear that the inhibition was due to enhanced antigen degradation by the treated M phi because responses were not reconstituted in the presence of excess antigen. After endotoxin or zymosan A treatment of the M phi population the proportion of Ia+ cells was reduced significantly, and surface expression of Ia antigen correlated with the ability of the cell population to present antigens to immune T cells. This suggested that endotoxin and zymosan A induce a loss of surface Ia antigen on antigen-presenting cells that inhibits immune T cell activation.

Increase of surface Ia-like antigen expression on human monocytes independent of antigenic stimuli.

Increase of surface Ia-like antigen expression on human monocytes independent of antigenic stimuli.

Human Ia-like antigens

Analysis of the tissue distribution of human Ia-like antigens has shown that they have a wider distribution than originally reported. Furthermore, the expression of Ia-like antigens may change when cells undergo malignant transformation: for instance, melanoma cells acquire Ia-like antigens, while breast carcinoma cells lose them. Serological and immunochemical analysis of Ia-like antigens with monoclonal antibodies has shown a cellular and molecular heterogeneity of these molecules which had not been previously recognized with conventional allo- and xenoantisera. The functional significance of this heterogeneity is not known. Monoclonal antibodies to human Ia-like antigens cross-react with lymphocytes from other animal species indicating that portions of the molecules have been conserved during evolution. The biological implications of these findings are discussed.