Antibody-induced antigenic modulation is antigen dependent: characterization of 22 proteins on a malignant human B cell line

Expression of several of the surface antigens on normal and malignant hematopoietic cells is reduced or is modulated by incubation with specific antibodies. Although antigenic modulation provides a means by which cells can escape antibody-mediated immune destruction, the physiologic significance and frequency of this phenomenon are both poorly understood. To begin to address these issues, we identified and characterized surface antigens on the malignant B cell line Laz 221 established from a patient with acute lymphoblastic leukemia (ALL). Indirect immunofluorescence analysis with the use of 26 hematopoietic cell populations and immune precipitation studies with the use of iodinated ALL cells indicate that 163 monoclonal antibodies (MoAb) identify 22 different proteins on this cell line, including at least six previously described surface molecules. Seven of these antigens are expressed by all nucleated cells examined, whereas only the mu chain of immunoglobulin is B cell specific. Incubation of specific MoAb with cultures of Laz 221 cells at 37 degrees C reduces or modulates surface expression of five of these 22 antigens (p45, immunoglobulin mu chain, transferrin receptor, common ALL antigen (CD10), and p105). Studies that made use of multiple MoAb specific for the same antigen suggest that the capacity for antigenic modulation is an intrinsic property of individual antigens. These studies also suggest that the murine immune response to shared human antigens varies from one immunizing cell population to another. For example, three of the antigens present on Laz 221 cells were only identified by MoAb raised to the Burkitt's cell line Ramos and vice-versa. Only one of these six shared antigens is present in greater amounts on the immunogenic cell population. Immunogenicity of individual human antigens in the mouse may be a function of their cell surface environment.     

Internalization and re-expression of antigens of human melanoma cells following exposure to monoclonal antibody

Modulation of the surface membrane of human Sk-Mel-28 melanoma cells by monoclonal antibody (MoAb) 96.5 recognizing p97 determinants was examined using direct radioimmunoassay and indirect fluorescent antibody-staining techniques. It was determined that the majority of 111In-labeled antibody that remained associated with cells after a 24-hr incubation at 37 degrees C had been internalized because MoAb 96.5 was no longer visible on the cell surface. A second treatment of these cells with the same antibody 24 hr later not only increased the cell-associated radioactivity, reflecting an increase of total antibody bound, but also rendered these cells membrane immunofluorescent again, indicating the re-expression of surface antigens. Autoradiographs of the electrophoretically analyzed membrane components of Sk-Mel-28 cells further demonstrated the appearance of newly synthesized 97-kDa proteins that were immunoprecipitable with MoAb 96.5. Taken together, the present findings suggest that p97 antigens undergo endocytosis in Sk-Mel-28 cells following exposure to MoAb 96.5. However, the same antigens were regenerated and expressed on the cell surface within a period of 24 hr. The re-expression of tumor cell surface antigen following initial internalization of the MoAb-antigen complex may have implications for diagnosis and therapy.     

Monoclonal antibodies against human myelomonocytic cells: detection of certain lineage-specific antigens on CFU-GM progenitor cells

A series of monoclonal antibodies (mAb) were raised against nonlymphoid leukemic cell lines. Three of them have been characterized in detail. mAb H8 (IgG2), mAB U2 (IgG1), and mAb ML143 (IgM) were established with HEL, an erythroleukemia cell line, U937, a monocytoid (histiocytic) line, and ML-1, a myeloid cell line as immunogen, respectively. A 65 to 75 KD polypeptide was precipitated from monocytes by mAb H8, a 160 KD protein from monocytes by mAb U2, and two broad bands in the regions of 150 and 195 KD from granulocytes by mAb ML143. All three mAb stained peripheral blood monocytes and granulocytes, but not lymphocytes, platelets, and erythrocytes. The mAb reacted with immature myeloid cells in bone marrow, ranging from myeloblasts to mature myelomonocytic cells. They also were reactive with various nonlymphoid cell lines and leukemia of myelomonocytic origin. They did not react with B cell lines and B cell CLL cells. By complement-mediated cytolysis and/or an immune rosette method, antigens H8 and U2 were found to be expressed on the vast majority of CFU-GM (14 days) progenitors but not on BFU-E. Antigen ML143 was not expressed by either progenitor. Furthermore, ML143 antigen was found on T leukemia cell lines, a subpopulation of mitogen-activated T cells, and certain non-T/non-B ALL cells. This reactivity was not found with mAb H8 and U2. The relationship between these mAb and those reported are discussed. The possibility of using these mAb to obtain a markedly enriched CFU-GM progenitor population is also raised.     

Expression of 18.6/CD23 Antigen on Human Lymphoid Progenitor Cell Lines and Phorbol 12-Myristate 13-Acetate (PMA)-Induced Microglia-Shaped Cells

The nature of lymphoid progenitors and factor(s) determining commitment to either the T- or B-lymphocyte pathway are poorly understood in the human system. In this study, we generated a monoclonal antibody (MoAb), 18.6, that recognizes a cell surface antigen on a human lymphoid progenitor cell line (FL4.4). MoAb 18.6 reacted with lymphoid progenitor lines, B lymphoid cell lines, and myelomonocytic cell lines. It did not react with any T cell or erythroid leukemic cell lines. Two color FACS analyses of normal lymphoid tissues showed that MoAb 18.6 reacted with a majority of CD20⁺ mature B cells and a minority of CD64⁺ monocytes. Molecules of 3 different sizes with MW of 34, 45, and 68 Kd were precipitated with MoAb 18.6 from the lymphoid progenitor cell line. The 18.6 antigen was not expressed on a fetal liver-derived lymphoid progenitor-like cell line, FL1.4, which has the capacity to differentiate into microglia-shaped cells upon PMA-stimulation. Stimulation of FL1.4 cells with PMA induced expression of the 18.6 antigen within 24 hr and the microglia-shaped cells stained positively with MoAb 18.6. Finally, cloning of a cDNA that encoded the 18.6 antigen revealed that the 18.6 antigen is identical to the CD23 antigen. Taken together, these data suggest that the 18.6/CD23 antigen is expressed on lymphoid precursors at a very early stage of differentiation.     

抗胃癌细胞系单克隆抗体PD4的初步研究

以胃癌细胞系MGC803免疫Balb/c小鼠,取其脾细胞与小鼠骨髓瘤细胞NS-1融合。经选择培养、筛选及克隆化,获得恒定地分泌抗胃癌细胞系单克隆抗体(MoAb)的杂交瘤细胞系PD4。MoAb PD4与3/4胃癌细胞系有强结合反应,与4/4肺癌细胞系有弱结合反应,但与淋巴细胞、ABO红细胞、骨髓细胞、二倍体成纤维细胞及经检测的其他肿瘤细胞均无反应。PD4抗原主要表达于靶细胞的膜上,不耐热,为分子量40kD的蛋白性抗原。该抗原与HLA抗原系统,血型抗原系统无关,亦不同于其他作者所报告的其他胃癌相关抗原。     

Differential expression of HLA-DR, -DQ, and -DP antigens on malignant B cells

HLA class II antigens mediate interactions among cells involved in the immune response and play an important role in the process of self recognition. We made use of conventional alloantisera and six well-characterized monoclonal antibodies (MoAb) to study the HLA class II antigens on CALLA-positive malignant B cell populations and autologous normal B cell lines. Forty additional HLA class II-specific MoAb were also tested for their ability to bind to these cells. By using indirect immunofluorescence and immune precipitation assays, we find that malignant B cells often fail to express one or more of the three known types of HLA class II antigens. Cell lines with the following five phenotypes have been identified: HLA-DR+, -DQ+, -DP+; HLA-DR+, -DQ-, -DP+; HLA-DR-, -DQ+, -DP+; HLA-DR-, -DQ-, -DP+; and HLA-DR-, -DQ-, -DP-. These cell lines have been used to characterize the subregion specificity of MoAb that react with HLA class II antigens. This work confirms the existence of complicated patterns of serologic cross-reactivity between the three different types of HLA class II molecules. It also increases our understanding of the specificity of individual MoAb, thereby facilitating future investigation of the distribution and function of individual antigens. Our studies are consistent with the proposal that altered expression of HLA antigens on tumors might impair recognition of these cells by the immune system of the host, thereby contributing to the proliferation of a malignant clone.     

Acute lymphoblastic leukemia (ALL) antigens detected with antisera to E rosette-froming and non-E rosette-forming ALL blasts.

Based on the presence or absence of erythrocyte receptors(E) a T cell marker, acute lymphocytic leukemia (ALL), can be divided into E+ALL and E-ALL. We studied cell surface antigens on blasts from 12 children with untreated ALL: eight with E-ALL and four with E+ALL. Heterologous antisera were raised against thymus cells, E+ and E-ALL blasts, appropriately absorbed and tested by immunofluorescence and a radiolabeled antibody assay with normal and leukemic lymphoid cells. By both methods, anti-thymus and anti-E+ALL sera reacted with human thymocytes. Specific binding of anti-E+ALL serum to T antigens was indicated by the fact that a single absorption with thymocytes abolished its binding to allogenic thymocytes, and the reactivity of anti-E+ALL serum with thymus, blood and bone marrow lymphocytes was similar to that of anti-thymus serum. After exhaustive absorption with blood leukocytes, anti-E+ALL and E-ALL sera were negative against normal lymphocytes and bone marrow cells from children with ALL in remission. Anti-thymus and anti-E+ALL sera reacted with blasts from patients with E+ALL, but not with E-ALL. In contrast, anti-E+ALL serum reacted with 40 to 96% of blasts from all children with E-ALL, whereas of the four patients with E+ALL, two were negative and two had the lowest percentage of immunofluorescent cells (10 to 22%). These results were confirmed with the radiolabeled antibody assay. Patients with active E-ALL had cells bearing E-ALL antigen(s) in the peripheral blood and bone marrow, but the number of immunofluorescent cells was lower in blood. Cells reactive with anti-E-ALL serum did not react with thymus cells, blood lymphocytes, remission bone marrow cells, Raji cells, PWM and PHA-induced blasts and CLL cells bearing mIg (uk). These data suggest that the antigen detected on E-ALL blasts by anti-E-ALL serum is neither a HLA-related nor a cell differentiation antigen. Thus, by using antiserum to E+ALL blasts, we have confirmed the presence of a T cell-specific antigen(s) on E+ALL cells. This antiserum did not recognize other leukemia-associated antigens common to E+ and E-ALL. We have also demonstrated an antigen(s) which is regularly expressed on E-ALL blasts and is either not detectable or is present in a lower proportion of E+ALL blasts.     

Unique subset of thymic epithelial cells defined by the expression of a novel neuroendocrine antigen

Murine monoclonal antibodies (MoAbs) were produced against a rat medullary thyroid carcinoma to identify neuroendocrine differentiation antigens. One of these antibodies (1D4) identified a novel 62- to 69-kDa antigen expressed by subsets of immune system epithelial and neuroendocrine cells. This antigen is expressed by distinct subsets of thymic epithelial and splenic reticular cells and is shared by discrete subsets of anterior pituitary and thyroid neuroendocrine cells. In the thymus, 1D4 expression identified a unique subset of stellate-shaped Ia+ medullary epithelial cells which did not react with thymosin alpha-1 antisera nor with the MoAb A2B5 specific for a GQ ganglioside expressed by thymic hormone-producing cells. The availability of the 1D4 MoAb should facilitate further characterization of 1D4+ immune system epithelial cells and may advance our understanding of neuroendocrine-immune system interactions.     

A unique antigen on mature B cells defined by a monoclonal antibody

A novel 42,000 dalton antigen (MB-1) expressed by mature human B cells in blood and tonsil was identified and characterized by utilizing a hybridoma monoclonal antibody. A comparison of MB-1 with other known B cell antigens suggests that the MB-1 antigen has not been previously identified. From one-and two-color immunofluorescence studies, it appears that the MB-1 antigen is found on all normal immunoglobulin (Ig)-expressing cells, but not on T cells, thymocytes, granulocytes, or platelets. Studies of malignant B cell tumors reveal that the antigen is expressed by virtually all Ig-expressing B cell tumors but only 10% of SIg- B-lineage leukemias. Data from these studies suggest that the MB-1 antigen is expressed late in B cell ontogeny before the expression of SIg.     

Distribution of antigenic determinants recognized by three monoclonal antibodies (Q2/70, Q5/6 and Q5/13) on human Ia-like alloantigens and on their subunits

The distribution of antigenic determinants recognized by the anti-Ia-like antigen monoclonal antibodies (MoAb) Q2/70, Q5/6 and Q5/13 on molecules coded for by the DR locus and by non-DR loci was investigated using a binding assay with 125I-labeled Ia-like antigens isolated from four B lymphoid cell lines. The determinants reacting with the MoAb Q2/70 and Q5/13 are expressed on all DR alloantigens tested and on BR4X7 specificities, while those reacting with the MoAb Q5/6 are not detectable on DRw7 and BR4X7 molecules. None of the monoclonal antibodies reacted with DC1 molecules. The MoAb Q5/6 and Q5/13 reacted with the isolated beta subunit of the Ia-like antigenic complex, while the MoAb Q2/70 did not react with the isolated chains.     

A Monoclonal Antibody Defining Human B Cell Differentiation Antigen (HLB-1 Antigen)

A new monoclonal antibody specific for human B cell differentiation antigen (HLB-1) is produced by a hybridoma established by fusion of splenocytes of mice immunized with the Epstein-Barr virus (EBV)-transformed peripheral B cell line, RPMI-8057. This monoclonal, antibody designated anti-HLB-1 monoclonal antibody (anti-HLB-1), reacted with surface immunoglobulin (sIg)-positive B cells of normal peripheral blood and lymphoid tissues and sIg-positive leukemic cells. The cells of T cell leukemia, non-T non-B acute lymphoblastic leukemia (ALL) and nonlymphoid leukemia were HLB-1 negative. These data were further confirmed by studying a panel of cultured human hematopoietic cell lines. Anti-HLB-1 reacted with B cell lines derived from pre-B, Burkitt's lymphoma, B cell type ALL and EBV-transformed peripheral B cells. Anti-HLB-1 was reactive with only one of three human myeloma cell lines, and with none of the T cell, myeloid and non-T non-B ALL cell lines. This newly defined HLB-1 antigen is different from other conventional human B cell markers such as sIg, Ia antigens, and receptors for the Fc portion of Ig and complement C3.     

Biochemical and immunohistochemical characteristics of CD62 and CD63 monoclonal antibodies. Expression of GMP-140 and LIMP-CD63 (CD63 antigen) in human lymphoid tissues.

During platelet secretion granule membrane glycoproteins are translocated to the plasma membrane. We report here the biochemical and immunohistochemical characterization of a panel of platelet-secretion-specific, CD62 and CD63 monoclonal antibodies (MoAb), which we raised to thrombin-activated platelets. The CD62 MoAb identify the alpha-granule membrane protein GMP-140, also designated platelet activation-dependent granule external membrane protein (PADGEM). The number of epitopes on thrombin-activated platelets ranged from 15,000 to 20,000. The CD63 MoAb recognize a 30-60 kDalton integral membrane protein of lysosomes. Due to its distinct localization, we have designated the CD63 antigen lysosome integral membrane protein, CD63 (LIMP-CD63). The number of epitopes on thrombin-activated platelets ranged from 9000 to 11,000. Expression of GMP-140, a member of the Selectin family (also referred as the LEC-CAM family) of adhesion molecules, and LIMP-CD63 was examined on human spleen, thymus and lymph node by immunohistochemistry. Both GMP-140 and LIMP-CD63 showed a wide distribution in lymphoid tissues; vascular endothelial cells and tissue compartments that were readily accessible to blood-borne components were uniformly positive for GMP-140 and LIMP-CD63. Furthermore, LIMP-CD63 was expressed in polymorphonuclear granulocytes and macrophages.     

Identification of several cell surface proteins of non-T, non-B acute lymphoblastic leukemia by using monoclonal antibodies

Monoclonal antibodies (MAb) were produced by immunization of BALB/c mice with cells from a non-T, non-B acute lymphoblastic leukemia (ALL) cell line. Nine distinct antigens (groups I to IX) were defined by these monoclonal antibodies, some of which appear to be associated with specific stages of cellular differentiation. The number of molecules of each MAb reactive with the ALL cell line, measured in a quantitative cellular radioimmunoassay, varied from 0.6 X 10(5) to 11 X 10(5) molecules/cell, indicating that the antigens identified represent major constituents of the cell surface. The biochemical nature of the antigens was examined on the ALL cell line by antibody affinity chromatography and/or immunoprecipitation and SDS-polyacrylamide gel electrophoresis. Groups I through III are composed of previously described antigens: HLA class I, HLA class II molecules, and CALLA, the common ALL antigen. The other MAb define antigens previously undescribed on non-T, non-B ALL cells. Group IV antigen is a polypeptide of apparent m.w. 95,000 distinct from CALLA. It is expressed on some ALL samples and on the vascular endothelial cells of several tissues. Group V antigen is a single polypeptide chain of m.w. 94,000, also distinct from CALLA and expressed by lymphocytes, thymocytes, acute myelogenous leukemia (AML) cells, and ALL cells. Group VI is a molecular complex composed of two noncovalently associated polypeptides of apparent m.w. 125,000 and 87,000 and appears to be restricted to ALL, AML, macrophages, and hematopoietic precursor cells. Group VII is a glycoprotein of apparent m.w. 85,000, which, within the thymus, is primarily restricted to the medullary area. It is also present on AML, bone marrow cells, and mature T and B lymphocytes. Group VIII is a disulfide-linked complex of apparent m.w. greater than 120,000 under nonreducing conditions. It is resolved into three major polypeptides of apparent m.w. 57,000, 47,000, and 41,000 under reducing conditions. This complex is found in greatest amounts on the non-T, non-B ALL cell line but is also present on AML, ALL, and on subpopulations of normal bone marrow and tonsil cells. Group IX antigen is a single polypeptide chain of apparent m.w. 51,000 on the ALL cell line. This antigen is expressed strongly on ALL and AML samples and on normal bone marrow; much lower antigenic density is found on thymus and tonsil cells. The antigens described here with a series of MAb produced in a single fusion represent a unique array of cell surface molecules of non-T, non-B ALL cells.(ABSTRACT TRUNCATED AT 400 WORDS)     

Characterization of an antigen expressed by human natural killer cells

A monoclonal antibody, anti-N901, was produced by fusing NS-1 myeloma cells with spleen cells of a mouse immunized with human CML cells. This antibody was reactive with a subpopulation of peripheral blood LGL, including the natural killer cells. Monocytes, granulocytes, B cells, T cells (T3+ cells), erythrocytes, and platelets were nonreactive. The N901-positive cells in the peripheral blood were heterogeneous with respect to expression of other cell surface antigens. The majority of N901+ cells co-expressed T11, Mo1, and HNK-1, whereas a smaller percentage expressed T8. Ia, T3, T4, Mo2, or B1 antigens were very uncommon on N901+ cells. The heterogeneity of the N901+ LGL was further investigated by examining the expression of N901 antigen on a series of cloned normal human NK cell lines. N901 antigen was expressed by each of the NK cell lines tested, and by a minority of cloned T cell lines without NK activity. Anti-N901 does not block NK activity and can be used to rapidly purify functional NK cells for further study.     

The detection of two surface antigens on human lung macrophages using monoclonal antibodies

Monoclonal antibodies (McAb), designated AMH1 (IgM, lambda) and AMH2 (IgG1, Kappa), against specific surface antigens of human lung macrophages were produced by the fusion of the NS-1 plasmacytoma cell line with spleen cells from BALB/c mice immunized with bronchoalveolar lavaged (BAL) cells obtained from selected smoking subjects. The screening and characterization of these McAb were carried out employing cellular radioimmunoassay, flow cytofluorography, and immunohistochemical methods. These two antibodies specifically reacted with macrophages in the alveolar spaces and BAL fluids. AMH1 did not react with peripheral blood cells including freshly separated monocytes, cultured monocytes, lymphocytes, granulocytes, and platelets. In addition, AMH1 did not react with peritoneal exudate cells or pleural exudate cells. On the other hand AMH2 showed the dull-positive reaction with some monocytes and pleural exudate cells among above-mentioned cells. These two McAb seemed to detect cell surface antigens that are expressed by highly differentiated or mature macrophages compared to OKM1. These antibodies will allow not only better characterization of immune cells but also assessment of maturity of lung macrophages.     

Appearance of B- or T-lymphocyte markers after diffusion chamber culture of acute lymphoblastic leukemia cells

Blast cells derived from blood and marrow samples of a patient with acute lymphoblastic leukemia (ALL), as well as from the Reh line originally established from an ALL patient, were cultured in diffusion chambers implanted i.p. into preirradiated CBA mice. At different intervals over a period of up to 20 days, surface immunoglobulins, ALL antigen, and T-cell antigen were investigated by using direct immunofluorescence. Rosette formation was tested with sheep and mouse erythrocytes. On day 0, the cells expressed only ALL antigen at the surface, and no rosette formation was observed. During culture the patient's lymphoblasts, which originally had cytoplasmic IgM in addition to ALL antigen, expressed surface immunoglobulins as well as mouse erythrocyte receptors. The Reh line cells were ambivalent in two experiments developing T-cell antigens and sheep erythrocyte receptors as well as mouse erythrocyte receptors. Our data suggest that the differentiation arrest in leukemic lymphoblasts can be overcome, thus entailing a surface pattern similar to mature T- or B-lymphocytes.     

Human granulocyte surface molecules identified by murine monoclonal antibodies

We have investigated the nature of the antigens recognized by four classes of mouse anti-human monoclonal antibodies that characteristically reacted with neutrophilic granulocytes and their precursor cells, but not with monocytes or other normal hemopoietic cells. The antigenic targets of the majority (9/12) of the independently isolated monoclonal antibodies were present on two surface glycoproteins (Mr 145,000 and 105,000) and glycolipids. This antigen(s) was also detected on granulocyte precursor cells, including the bone marrow granulocyte/monocyte progenitor cells (CFU-GM). The same antigen(s) detected by these monoclonal antibodies was also present in non-hemopoietic cell lines (colon carcinoma and neuroblastoma). Three other antigens, defined by monoclonal antibodies AHN-8, L12.2, and L13.1 and present on granulocytes and their mid-late precursor cells, could not be identified as proteins but were detected in a protein-free glycolipid extract of these cells. The diversity of the antigens was confirmed by cross-competition experiments and by the identification of their different patterns of reactivity with cell lines and bone marrow cells.     

Preparation and characterization of monoclonal antibodies recognizing three distinct differentiation antigens (BL1, BL2, BL3) on human B lymphocytes

We report in this paper the generation and characterization of three monoclonal antibodies, designated alpha BL1, alpha BL2, and alpha BL3, that recognize distinctive antigens unrelated to complement, Fc, and mouse erythrocyte rosette receptors, which are preferentially expressed on B lymphocytes. alpha BL1 recognizes a heat stable nonimmunoprecipitable antigen, possibly glycolipid in nature. Alpha BL2 recognizes a nonreducible single polypeptide with a m.w. of 68,000 that occasionally co-precipitates with a p29,34 complex of HLA-DR antigens. Alpha BL3 recognizes a nonreducible single polypeptide with a m.w. of 105,000 with an acidic pI point. We demonstrated that BL1 is expressed on fetal liver hematopoietic cells, a small subset (5 to 15%) of Ficoll-Hypaque-separated normal bone marrow cells, and on a subpopulation of nonadherent, non-E rosette-forming cells and granulocytes. BL2 is expressed on fetal liver hematopoietic cells, on 3 to 7% of normal bone marrow cells, and on a majority (40 to 70%) of nonadherent, non-E rosette-forming cells with a distinctive pattern similar to that of HLA-DR. BL3 is expressed on a subpopulation of nonadherent, non-E rosette-forming cells, and on occasional cells in the monocyte-enriched adherent cell population. The peak fluorescence for BL2 is substantially higher than that of BL1 and BL3, indicating higher BL2 antigen density. All three antigens are absent from thymocytes and E rosette-positive T cell fractions obtained from various lymphoid tissues. Cellular distribution of the BL antigens on various well-characterized established hematopoietic cell lines, leukemias, and malignant lymphomas, in conjunction with the results of the in vitro activation and TPA-induction experiments, suggest that BL1 is expressed during early developmental stages of B cell differentiation, whereas BL3 is expressed at the later stages. BL2 expression spans immature and mature stages of B cell differentiation, with the exception of mature plasma cells. The alpha BL antibodies described here should prove to be useful in the investigation of B cell differentiation and in the clinical diagnosis of lymphoid neoplasms.     

Expression of ABH and X (Lex) antigens in various cells

Using a panel of reagents specific to the various subtypes of ABH antigens, it could be demonstrated that platelets carry ABH type 2 monofucosylated determinants on intrinsic glycoproteins. The presence of these antigens is controlled by the H gene and correlates with the presence of alpha-2-L-fucosyltransferase and the absence of alpha-3-L-fucosyltransferase. In contrast, intrinsic ABH antigens were not found on mononuclear cells, correlating with the absence of alpha-2-L-fucosyltransferase on these cells. However, after transformation with the Epstein-Barr virus and stimulation with 12-O-tetradecanoylphorbol-13-O-acetate (TPA), B lymphocytes were found to express the H antigen under control of the H gene and not the Se gene. The lymphoblastoid cell lines also expressed the X and sialylated X antigens which are normally markers of the myeloid lineage. These antigens are also normally found in epithelial cells of the digestive tract, kidney proximal convoluted tubules and hepatocytes. The alpha-3-L-fucosyltransferase responsible for the synthesis of this antigen is present in the serum but we report the existence of two individuals, a mother and her daughter, who lack more than 90% of this serum enzyme. The young girl suffers from a congenital kidney anomaly: oligomeganephronic hypoplasia. Her kidney tubules are devoid of X antigen. However, she and her mother have the X antigen on their granulocytes and its sialylated form on their monocytes. It therefore appears that there are distinct genetic controls for the expression of antigen X in different body compartments. This would be quite similar to the H and Se gene controls in tissues of distinct embryological origins.     

Serologic and immunochemical characterization of the specificity of four monoclonal antibodies to distinct antigenic determinants expressed on subpopulations of human Ia-like antigens

Serologic and immunochemical assays showed that the monoclonal antibodies Q2/70, Q2/80, Q5/6, and Q5/13 react with human Ia-like antigens. Each monoclonal antibody recognizes distinct antigenic determinants that are different from those defining the serologic polymorphism of Ia-like antigens defined by conventional alloantisera and are expressed on subpopulations of Ia-like antigens. The determinants recognized by the MoAb Q2/70 and Q5/13 are expressed on all HLA-DR allospecificities tested, whereas those reacting with the MoAb Q2/80 and Q5/6 are not detectable on HLA-DR5 and HLA-DR7 allospecificities, respectively.