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PubMed1984

Distinctive phorbol ester-induced morphological and surface antigen changes in mycosis fungoides, the Sézary syndrome, and adult T-cell leukemia.

Clinical and pathological studies of cutaneous T-cell lymphomas (CTCL) reveal variations in tumor cell morphology and surface membrane phenotype that are of diagnostic and prognostic importance. Our study investigates blastic transformation and surface antigen change on CTCL cells in vitro under the influence of tumor-promoting phorbol ester (TPA) and phytohemagglutinin. Both agents transformed tumor cells with cerebriform nuclei into blast cells within 5 days; however, Sézary cells were somewhat resistant to transformation with phytohemagglutinin. Multinucleated cells with prominent nucleoli resembled Reed-Sternberg cells of Hodgkin's disease. These morphological changes simulated the appearance of the aggressive tumor stage of mycosis fungoides. During blastic transformation, the erythrocyte rosette receptor was induced by TPA on sheep erythrocyte-rosette-negative Sézary cells from one patient. During the first 24 hr in vitro, Sézary and MF cells stimulated by TPA lost Leu 3a (T4) antigen while maintaining original high levels of Leu 1 antigen. In contrast, leukemia cells from patients with adult T-cell leukemia (ATL) were resistant to modulation of Leu 3a antigen by TPA; 3A1 antigen on CTCL and ATL cells was unaffected by TPA. Blastic transformation of CTCL cells was observed with both TPA and phytohemagglutinin, but helper T-cell antigen Leu 3a (T4) and erythrocyte rosette receptor changes occurred only with TPA. Thus, blastic transformation and surface differentiation were not directly related. These results provide a possible model for the study of blastic transformation and surface antigen/receptor variation in CTCL. They also may provide an independent test for the distinction of CTCL and ATL in vitro. Finally, they illustrate the relative resistance of ATL to surface antigen modulation as previously shown for Tac antigen modulation by anti-Tac antibody.

Adult↗
PubMed1999

Schistosomal granuloma modulation. I. Schistosoma mansoni worm antigens CAA and CCA prime egg-antigen-induced hepatic granuloma formation.

Adult Schistosoma mansoni worms can positively modulate soluble egg antigen (SEA)-induced granulomas formed around SEA-coupled beads implanted in the liver. In this study, our aim was to further unravel the immunopathological characteristics of S.mansoni-worm-derived antigens in vivo. (a) Adult worm antigen (AWA)-coupled Sepharose beads, implanted into the liver, induced granulomas, containing numerous eosinophilic granulocytes and elicited marked periparticular fibrosis (composed of interstitial matrix proteins and basement membrane components). (b) Quantitative morphological analysis demonstrated that in naive mice, AWA-induced hepatic granuloma formation peaked in volume 16 days after injection of the beads. An accelerated response against AWA-coupled particles (peak volume at 8 days) was observed in mice carrying a single-sex, male S. mansoni infection. (c) When the granuloma volume induced by SEA-coupled beads in unisexually S. mansoni infected mice was compared to granulomas induced by beads laden with both SEA and AWA in unsensitized mice, no significant differences in granuloma volume were seen, indicating the existence of in vivo egg/worm antigen cross-sensitization. (d) Naive mice, sensitized with the worm antigens circulating anodic antigen (CAA) or circulating cathodic antigen (CCA), mounted a strongly accelerated response towards SEA-coupled beads implanted in the liver. We infer that, in vivo, worm antigens cross-sensitize with egg antigens and have both granulomogenic and fibrogenic characteristics. The S. mansoni soluble worm antigens CCA and CAA prime hepatic egg-antigen-induced granuloma formation possibly through the presence of immunogenic carbohydrates. These mechanisms lead to an accelerated response against SEA.

Animals↗
PubMed1976

Virus-enhanced modulation of cell surface antigens: effect on immune lytic susceptibility.

Monkey kidney cells, upon progressive subculture, became refractory to complement (C)-dependent immune cytolysis by anti-cell serum. Arbovirus infection restored these cells to a state of lytic susceptibility. Similar results were also abtained with antibody-dependent cellular cytotoxicity (ADCC), which is C independent. Antibodies raised against different subcultures varied considerably in lytic efficiency, indicating changing patterns of host cell expression during continous subculture. Taken together with the fact that arbovirus infection festored the lytic efficiency of all antibody preparations to the same degree suggested some form of host cell antigen re-expression as a mechanism. The results obtained in several exploratory experiments indicated that the antigenic re-expression responsible for the restoration of lysis was probably a local or selective rather than a generalized phenomenon. Thus, the amount of host cell surface antigen, measured by the use of mouse anti-cell serum and 125I anti-mouse globulin, was identical in both uninfected lytic susceptible and refractory cells, and decreased in both functional states following infection. Further, the binding of 125I concanavalin A, used to quantify surface glycoproteins, was similar in both lytic refractory and susceptible cells, and in both cases declined folowing virus infection. This result was incompatible with gross "masking" of cell surface antigens by exuberant production of surface coat material in lytic resistant cells. Finally, brief trypsinization of lytic resistant cells yielded an 8-fold increase in immune lysis, a result further consistent with local rather than generalized surface changes. The data were discussed interms of modulation of cell surface antigens affected both by repeated subculture and arboviral infection, and as a possible in vitro correlate of altered self-reactivity.

Animals↗
PubMed2001

Cytotoxic T lymphocyte antigen 4 and CD28 modulate cell surface raft expression in their regulation of T cell function.

Coreceptors CD28 and cytotoxic T lymphocyte antigen (CTLA)-4 have opposing effects on TcR/CD3 activation of T cells. While CD28 enhances and CTLA-4 inhibits activation, the underlying molecular basis of these effects has yet to be established. In this context, ganglioside and cholesterol enriched membrane microdomains (rafts, GEMs) serve as centers of signaling in T cells. Although CD28 can promote TcR/raft colocalization, evidence is lacking on whether the surface expression of membrane rafts can be targeted by CTLA-4 in its modulation of T cell responses. In this study, we demonstrate that both CD28 and CTLA-4 profoundly alter the surface expression of membrane rafts during T cell activation. While CD28 increased expression and the number of peripheral T cells induced to express surface rafts in response to TcR ligation, CTLA-4 potently inhibited both TcR and TcR x CD28 induced raft expression on the surface of T cells. Consistent with this, CD28 increased the presence of the linker of activated T cells (LAT) in purified membrane rafts, while CTLA-4 coligation effectively blocked this increase. Further, the reversal of the CTLA-4 block with CD3/CD28 ligation was accompanied by an increase in surface raft expression and associated LAT. Our observations demonstrate for the first time that CTLA-4 targets the release of rafts to the surface of T cells, and provides a mechanism for the opposing effects of CD28 and CTLA-4 on costimulation.

Abatacept↗
PubMed1993

Modulation of proliferation and antigen expression of a cloned human glioblastoma by interleukin-4 alone and in combination with tumor necrosis factor-alpha and/or interferon-gamma.

As part of continuing studies to investigate the possible regulatory effects of cytokines on malignant astrocytes, we investigated the effects of interleukin-4 (IL-4) alone and in combination with tumor necrosis factor-alpha (TNF alpha) and/or interferon-gamma (IFN gamma) on the cell growth and major histocompatibility complex (MHC) antigen expression of a cloned human glioblastoma cell line (9C). The 9C cells were treated with IL-4 alone or in combination with TNF alpha and/or IFN gamma and were examined for proliferation by crystal violet assay and for Class II MHC antigen by flow cytometry. Results indicated that IL-4 alone did not affect 9C proliferation. In combination with TNF alpha or IFN gamma, however, IL-4 significantly and dose-dependently inhibited cell growth. As previous reports have shown, TNF alpha combined with IFN gamma exerted an additive growth suppressive effect on glioblastoma cells, probably by enhancing TNF receptor expression. This additive effect of TNF alpha and IFN gamma was further enhanced by IL-4. In contrast, IL-4 did not modulate expression of Class II MHC antigen on 9C cells, even in combination with IFN gamma, which predictably enhanced this antigen. These results suggest that IL-4 is capable of modulating glioblastoma growth only in the presence of other cytokines, such as TNF alpha and/or IFN gamma. Further, the effect of IL-4 on glioblastoma proliferation is selective and independent of the mechanisms involved in regulating MHC antigen expression.

Brain Neoplasms↗
PubMed1990

Second messenger-induced modulation of Thy-1 antigen expression: an ELISA study using murine thymic and neuroblastoma cells.

Freshly isolated cells of murine thymuses and in vitro cultured murine neuroblastoma cells were seeded into microplates, treated with either phorbol myristate acetate (PMA) or dibutyryl-cyclic adenosine monophosphate (DBcAMP), and then processed for enzyme immunoassay to analyze with G4 monoclonal antibody the expression of Thy-1.2 antigen epitope. Pretreatment of thymic cells with PMA resulted in little, if any, decrease of Thy-1 expression, while treatment of these cells with DBcAMP caused a significant down-modulation of the epitope. DBcAMP did not affect binding of another murine IgG antibody to the thymic cells. Modulation of the epitope on thymic cells caused by DBcAMP was dose-dependent with maximal effect seen at the drug concentration of 10(-4) M. However, at various doses of DBcAMP (10(-6) to 10(-3) M) we were unable to detect any significant shift of Thy-1 expression on neuroblastoma cells. Though mechanisms of the above phenomena need further elucidation, we conclude that cellular ELISA may provide a useful alternative to more commonly used cytofluorimetric studies for the analysis of immune cell-surface antigen expression and its pharmacological and physiological modulation.

Animals↗
PubMed1987

Modulation of monocyte Mo2 surface antigen expression by exposure to respiratory syncytial virus.

The Mo2 antibody recognizes a monocyte-specific cell surface antigen of unknown function. Upward modulation of Mo2 surface epitope density was demonstrated in response to 72-hr culture of monocytes with respiratory syncytial virus (RSV), but this was not seen after culture with phytohemagglutinin or other respiratory viruses. Monoclonal antibody probes for RSV proteins were used to demonstrate probable replication of RSV proteins in peripheral blood monocytes and pulmonary alveolar macrophages. These data provide possible clues to the biologic role of the Mo2 antigen.

Antibodies, Monoclonal↗
PubMed1985

Serological study for in vitro use of monoclonal antibody for autologous bone marrow transplantation in null cell-type acute lymphocytic leukemia.

In connection with autologous bone marrow transplantation (BMT) in null cell-type acute lymphocytic leukemia (Null-ALL) patients, the optimal conditions for in vitro elimination of leukemia cells from transplanted bone marrow cells with monoclonal antibodies (MoAb) plus rabbit complement (C) were investigated. Three monoclonal antibodies, NL-1, NL-22 and HL-47, which were produced in our laboratories and shown to react predominantly to Null-ALL cells, were used. In most cases, 10 micrograms/ml of MoAb and 50% of C were required for optimal killing of leukemia cells. Combined use of MoAbs and multiple treatments were studied, but generally no significant increase in the cytotoxicity to the target leukemia cells was observed as compared with a single treatment with the most effective single MoAb. Selection of C was very important, because some lots had lower C activity from the beginning or after incubation with normal bone marrow mononuclear cells. Nonspecific cytotoxicity to human hematopoietic cells was also observed in some lots of C. Under the optimal conditions thus defined, the three MoAbs did not inhibit the growth of granulocyte-macrophage colony-forming units (CFU-GM) or three other types of hematopoietic stem cells. Modulation of the antigens was also examined, and NL-1 antigen showed mild modulation, whereas NL-22 and HL-47 antigen did not. The results obtained indicated that these three MoAbs may be useful for eliminating Null-ALL cells in vitro from bone marrow in autologous BMT.

Antibodies, Monoclonal↗
PubMed1981

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.

Animals↗
PubMed1999

Functional analysis of genes responsible for the synthesis of the B-band O antigen of Pseudomonas aeruginosa serotype O6 lipopolysaccharide.

This study reports the organization of the wbp gene cluster and characterization of a number of genes that are essential for B-band O antigen biosynthesis in the clinically prevalent Pseudomonas aeruginosa serotype 06. Twelve genes were identified that share homology with other LPS and polysaccharide biosynthetic genes. This cluster contains homologues of wzx (encoding the O antigen flippase/translocase) and wzz (which modulates O antigen chain length distribution) genes, typical of a wzy-dependent pathway. However, a complete wzy gene (encoding the O-polymerase) was not found within the cluster. Four biosynthetic genes, wbpO, wbpP, wbpV and wbpM, and four putative glycosyltransferase genes, wbpR, wbpT, wbpU and wbpL, were identified in the cluster. To characterize their roles in LPS biosynthesis, null mutants of wbpO, wbpP, wbpV, wbpL and wbpM were generated using a gene-replacement strategy. Mutations in each of these genes caused deficiency in B-band synthesis. The wbpL mutant was deficient in both A-band and B-band LPS. WbpL(O6) is a bi-functional enzyme which could initiate B-band synthesis through the addition of QuiNAc to undecaprenol phosphate, and A-band synthesis by transferring either a GalNAc or a GlcNAc residue. Another approach used to assign function to the wbp(O6) genes was by complementation analysis. Two genes from Salmonella typhi, wcdA and wcdB, responsible for the synthesis of a homopolymer of GalNAcA called Vi antigen were used in complementation experiments to verify the functions of wbpO and wbpP. wcdA and wcdB restored B-band synthesis in wbpO and wbpP mutants respectively, implying that wbpO and wbpP are involved in UDP-GalNAcA synthesis. Although wbpV has homology to wbpK of the serotype O5 B-band LPS synthesis cluster, complementation analysis using the respective null mutants showed that the genes are not interchangeable. A knockout mutation of wbpN (located downstream of wbpM) did not abrogate LPS synthesis in either 05 or 06; therefore, it has been renamed orf48.5. These results establish the organization of genes involved in P. aeruginosa B-band O antigen synthesis and provide the evidence to assign functions to a number of LPS biosynthetic genes.

Amino Acid Sequence↗
PubMed1991

Antigen handling by the epithelium and lamina propria macrophages.

The absorptive enterocyte of the small intestine expresses MHC class II antigens both constitutively and as a result of induction by cytokines. This can function to restrict antigen presentation in vitro. However, there is no direct evidence that its function in vivo is to restrict the presentation of absorbed soluble protein antigens to the available intraepithelial lymphocyte population. Alternatively, the class II molecule may be acting as a receptor for immunologically relevant antigen and transporting this antigen in a protected route across the epithelium. A third possibility concerns a possible educational role for epithelial class II. The epithelium of the intestine is identical in embryologic origin to thymic epithelium, which is known to be involved in the positive selection of alpha/beta TCR CD4-positive and CD8-positive T cells. The early development in ontogeny of epithelial and lamina propria cells expressing class II, the association of gamma/delta TCR with IEL (at least in rodents), and the reported thymus independence of these gamma/delta IEL26 all support speculation that the Ia-positive cells of the lamina propria in the fetus and the epithelium in the adult cooperate to restrict the diversity of the response to bacterial antigens and, in the antigen-free fetal state, to self-antigens. A mechanism providing constant positive selection or tolerization of T cells responsive to bacterial or food antigens would be very beneficial. The macrophage/dendritic lineage cells of the lamina propria can present antigen and modulate the response to that antigen. Because the subpopulations of these cells in the lamina propria are distinct from the antigen-handling cells of Peyer's patches, however, it is likely that the follicular and diffuse lymphoid tissues have evolved either to respond to different types of antigen or to induce and regulate different responses to the same antigen.

Animals↗
PubMed1987

Modulation of the nuclear antigen p105 as a function of cell-cycle progression.

The characterization of the proliferation-associated nuclear antigen designated p105 in quiescent and proliferating lymphocytes is described. Through the use of novel flow cytometric and cell-sorting strategies the intracellular content of p105 was assessed in situ on a per cell basis. These analyses demonstrated the presence of multiple cellular subpopulations within the cell cycle differing significantly in p105 content. The data revealed that the flow cytometric quantitation of p105 levels may effectively discriminate cycling from noncycling cells. Immunogold electron microscopy revealed that the modulation of this interchromatin-associated antigen was correlated with a significant degree of nuclear restructuring. In conjunction with cell sorting, immunogold electron microscopy and immunoblot controls demonstrated that the cell-cycle-related modulation in p105 cannot be accounted for by increased cellular mass or antigen sequestration. The significance of these controls and of the potential role of p105 in cellular proliferation is discussed.

Autoantigens↗
PubMed1987

Modulation of human tumor antigen expression.

With membrane-enriched fractions prepared from human metastatic breast tissue used as immunogen, a group of monoclonal antibodies (MAbs) were generated that recognized several distinct antigens on breast and other carcinomas. The antibodies were found to react with established human tumor cells in culture as well as in immunohistochemical protocols using sections of primary and metastatic lesions. One MAb, B72.3, demonstrated a high degree of selective reactivity for human carcinomas in that no reactivity was found with a large number of different normal tissues. These MAbs were used to demonstrate the heterogeneity of expression of the tumor antigens as well as the intrinsic cellular factors (i.e., cell-cycle kinetics and clonal variability) that modulate their expression. Additional studies showed that recombinant human leukocyte interferon can act as a potent regulator of surface antigen expression on human carcinoma cells. Analysis of these cells by radioimmunoassay or flow cytometry revealed that interferon treatment resulted in a higher percentage of the cell population that bind the MAb to the surface antigen. Furthermore, interferon treatment also increases the level of expression for particular tumor antigen throughout the tumor cell population. Experimental models were also developed to investigate the active localization of a radiolabeled MAb by a human tumor xenograft in athymic mice. The results demonstrate active uptake of an 125I-B6.2 by a transplantable human breast tumor that expressed significant quantities of the B6.2-reactive 90 kD tumor antigen. In contrast, a human melanoma cell line grown as a solid, subcutaneous tumor in athymic mice did not localize the labeled B6.2 and does not express the associated 90 kD antigen. We report the generation and characterization of anti-breast carcinoma MAbs. These immunologic probes were used to study relevant breast tumor antigens, the factors that influence their level of expression, and the ability of human tumors grown in athymic mice to localize radiolabeled antibodies.

Animals↗
PubMed2004

Recruitment of different subsets of antigen-presenting cells selectively modulates DNA vaccine-elicited CD4+ and CD8+ T lymphocyte responses.

The immunogenicity of plasmid DNA vaccines may be limited by the availability of professional antigen-presenting cells (APC) at the site of inoculation. Here we demonstrate that the types of APC recruited to the injection site can selectively modulate CD4(+) or CD8(+) T lymphocyte responses elicited by an HIV-1 Env DNA vaccine in mice. Coadministration of plasmid GM-CSF with the DNA vaccine resulted in the recruitment of macrophages to the site of inoculation and specifically augmented vaccine-elicited CD4(+) T lymphocyte responses. In contrast, coadministration of plasmid MIP-1 alpha with the DNA vaccine resulted in the recruitment of dendritic cells to the injection site and enhanced vaccine-elicited CD8(+) T lymphocyte responses. Interestingly, coadministration of both plasmid GM-CSF and plasmid MIP-1 alpha with the DNA vaccine recruited both macrophages and dendritic cells and led to a synergistic and sustained augmentation of CD4(+)and CD8(+) T lymphocyte responses. These data demonstrate the critical importance of locally recruited professional APC in determining the magnitude and nature of immune responses elicited by plasmid DNA vaccines. Moreover, these studies show that different subsets of professional APC can selectively modulate DNA vaccine-elicited T lymphocyte responses.

Animals↗
PubMed1989

Blood group-related antigens in human kidney: modulation of Lewis determinants in renal cell carcinoma.

Seven mouse monoclonal antibodies and the lectin Ulex europaeus, detecting blood group related antigens of the ABH and Lewis systems, have been used to determine the immunophenotype of human renal cell carcinomas. Immunohistochemical analyses have demonstrated that these antigenic systems are differentially expressed by distinct normal cell types and domains of the human nephron. In the present study we analyzed the immunophenotype of 29 primary and 15 metastatic renal carcinomas by the immunoperoxidase method. Blood type was known in all of the cases and secretor status in nine cases. ABH specificities were not detected in tumor cells of the primary tumors studied, although two of the metastases showed heterogeneous expression of H and A antigens, respectively. Lewisx (Lex) determinant was detected in 76% of primary renal cell carcinomas; however, Lex was only expressed by occasional cells in 20% of the metastatic tumors analyzed. Lewisa (Lea) was detected with a heterogeneous pattern of expression in 31% of the primary and 26% of the metastatic renal tumors studied. Lewisy (Ley) antigen expression was found in 17% of the primary and 20% of the metastatic tumors analyzed. Detection of precursor type 1 structure was observed in 28% of primary and 20% of metastatic renal cell carcinomas. The present study suggests the histogenesis of renal cell carcinoma in the proximal nephron, based on the expression of Lex and Lea antigens. It also shows: (a) an apparent deletion, downregulation or structural modification of Lex determinant in most of the metastatic tumors; (b) undetectable levels of ABH specificities in tumor cells of primary renal cell carcinoma; and (c) enhanced expression and/or neosynthesis of precursor type 1 structure and Ley determinant in some renal cell carcinomas.

ABO Blood-Group System↗
PubMed1987

The modulation of class II histocompatibility antigens and 'activated' macrophage determinant in the spinal cord during the development of chronic relapsing experimental allergic encephalomyelitis (CREAE) in the guinea pig--relevance to the induction of remission?

Cryostat sections of spinal cord of guinea pigs with chronic relapsing experimental allergic encephalomyelitis (CREAE) were stained with monoclonal antibodies recognising a Strain 13-specific Ia epitope, a non-strain-specific Ia antigen and an 'activated' macrophage determinant. It was found that both Ia antigens and the 'activated' macrophage determinant, observed on infiltrating cells within both perivascular and meningeal compartments, appeared to be modulated during the course of CREAE. This correlated with the neurological symptoms of the disease. Blood vessels and 'glial' cells expressed both Ia determinants. 'Glial' cells also expressed the 'activated' macrophage antigen. These antigens were modulated with the course of the disease.

Animals↗
PubMed1987

Abnormal expression of class I and class II major histocompatibility antigens in alopecia areata: modulation by topical immunotherapy.

Fifty-eight scalp biopsies were immunohistologically investigated with monoclonal antibodies against HLA-ABC, HLA-DR, and T6 antigens. The following 3 groups were compared: control biopsies obtained from healthy volunteers (n = 5) or patients with unrelated scalp diseases (n = 6); biopsies from untreated alopecia areata (AA), obtained either from untreated patients (n = 19) or from the untreated side in patients receiving unilateral treatment with the contact allergen diphencyprone (DCP) (n = 13); biopsies obtained from the treated side in patients receiving unilateral treatment with DCP (n = 13). While HLA-ABC antigens were strongly expressed by epidermal keratinocytes and the infundibular epithelium of hair follicles in all biopsies, these antigens were either not detectable or only faintly expressed on the subinfundibular epithelium and the hair matrix in the control series. By contrast, 30 out of 32 biopsies from untreated AA showed expression of HLA-ABC antigens on hair matrix epithelium, and the subinfundibular epithelium was HLA-ABC-positive in 15 out of 32 cases. In the biopsies from treated AA, HLA-ABC antigens were expressed on hair matrix epithelium in 9 out of 13 cases, and on the subinfundibular epithelium in 1 case. In the controls and untreated AA, HLA-DR expression was confined to dendritic cells in the epidermis and the follicular infundibulum. Its expression on hair matrix epithelium was found in 15 out of 32 biopsies from untreated AA and in 4 out of 13 biopsies from treated AA. In the control series, intrabulbar T6+ dendritic cells were either absent or present in low numbers. High numbers of intrabulbar T6+ cells were present in 7 out of 32 biopsies from untreated AA and in 0 out of 13 biopsies from treated AA. The data show that abnormal expression of class I major histocompatibility (MHC) antigens on hair matrix epithelium is a constant feature in AA, whereas class II MHC antigens are less frequently expressed. Topical immunotherapy with DCP, which induced expression of HLA-DR in epidermal keratinocytes in 6 out of 13 cases, reduced the abnormal expression of both HLA-ABC and -DR antigens in the epithelium of lower hair follicles in AA.

Alopecia Areata↗