Lesional Keratinocytes Research Articles

Co-Localized Overexpression of GRO-α and IL-8 mRNA Is Restricted to the Suprapapillary Layers of Psoriatic Lesions

Epidermal infiltration by polymorphonuclear cells is a prominent feature in psoriatic lesions. Expression of neutrophil-specific chemoattractants by lesional keratinocytes could play an important role in the regulation of this infiltration process. We therefore examined the mRNA expression of GRO-alpha, a well-characterized peptide with neutrophil-specific activation profile in psoriatic lesions by in situ hybridization. Clusters of clearly detectable and in some cases highly abundant GRO-alpha hybridization signals could be demonstrated in the differentiated layers of psoriatic epidermis. The signals were clearly associated with keratinocytes, with no nearby neutrophils detectable by microscopic examination. When additional tissue sections of GRO-alpha-expressing lesions were examined with an interleukin-8/neutrophil-activating peptide-8 (IL-8)-specific anti-sense probe, IL-8 expression was detectable and confined to areas also expressing GRO-alpha. Expression of both GRO-alpha and IL-8 is focally upregulated by an as yet unknown mechanism in lesional psoriatic keratinocytes, ultimately leading to neutrophil tissue infiltration. We suggest that the focal expression of GRO-alpha and IL-8 in the epidermal layers above the dermal papillae may be involved in the "squirting papilla" reaction described as a characteristic feature of psoriatic plaque-type lesions.

Topical treatment of psoriatic plaques with 1 alpha, 24 dihydroxyvitamin D3: a multiparameter flow cytometrical analysis of epidermal growth, differentiation and inflammation.

The clinical efficacy and tolerability of the vitamin D3 analogues calcitriol, calcipotriol and 1 alpha, 24 dihydroxyvitamin D3 in the treatment of psoriasis have been assessed in various clinical studies. In vitro and in vivo investigations have shown interference of these compounds with epidermal growth, keratinisation and inflammation. In this study we quantified the in vivo cell biological effects during treatment of psoriatic plaques with 1 alpha, 24 dihydroxyvitamin D3. By using a flow cytometric triple labelling procedure, we could discriminate different epidermal subpopulations, permitting precise assessment of epidermal cell cycle kinetics. Twenty patients with plaque-type psoriasis were treated in a double-blind placebo-controlled left-right comparative study with 1 alpha, 24 dihydroxyvitamin D3 ointment (4 micrograms/g applied once daily) for 8 weeks. Epidermal cell suspensions prepared from keratotome biopsies taken before and after treatment were stained with TO-PRO-3 iodide (a new DNA fluorochrome) and monoclonal antibodies against keratin 10 (as a marker for differentiation) and vimentin (as a marker for inflammation), simultaneously. The flow cytometric analyses showed a significant decrease of proliferating basal keratinocytes in verum-treated lesions, whereas such a decrease was not observed in placebo-treated lesions. The amount of keratin 10-positive keratinocytes increased and the presence of vimentin-positive cells decreased in cell suspensions derived from both verum- and placebo-treated lesions, but these effects were not significant. We conclude that multiparameter flow cytometry promises to be an adequate approach to assess the interference of antipsoriatic treatments with cutaneous inflammation, epidermal proliferation and keratinisation. Topical 1 alpha, 24 dihydroxyvitamin D3 seems to exert its in vivo antipsoriatic effect mainly through an inhibition of epidermal growth.

Variational expression of functionally different macrophage markers (27E10, 25F9, RM3/1) in normal gingiva and inflammatory periodontal disease

Keratinocytes and macrophages share under immunologically activated conditions several surface proteins. We investigated immunohistochemically with monoclonal antibodies and the APAAP technique the expression pattern of 27E10 antigen (inflammatory macrophages), 25F9 antigen (resident macrophages) and RM3/1 antigen (intermediate macrophages in healing tissue) in 29 specimen biopsies of different stages of gingivitis and periodontitis. Macrophages of each subtype exhibited a different localization pattern depending on the stage of inflammation. Furthermore, suprabasal oral gingival epithelia showed a constant 27E10 expression, independent of the stage of inflammation. In contrast, all layers of the sulcus and pocket epithelia in gingivitis and periodontitis were strongly 27E10-positive, indicating immunological activation. 25F9 antigen was expressed on basal keratinocytes independent of the stage of inflammation, whereas RM3/1 was constantly negative on keratinocytes. The expression pattern of these functionally different macrophage markers on lesional macrophages and keratinocytes indicates varying differentiation and activation and suggests a participation of these cells in the local immune response in periodontal infection.

Regulatory Effects of Antipsoriatic Agents on Interleukin-1 α Production by Human Keratinocytes Stimulated with Gamma Interferon in vitro

It is known that keratinocytes produce and secrete interleukin-1 (IL-1) de novo and that this process can be enhanced by various stimulators. IL-1 has been shown to be a potent proinflammatory cytokine which mediates inflammation in various cutaneous disorders. It has also been demonstrated that gamma-interferon (IFN-gamma) which is released from infiltrated T cells can be detected in inflamed lesional sites. In order to understand the effects of IFN-gamma on IL-1 production by keratinocytes in such inflammatory lesions, normal human keratinocytes (NHKs) and human squamous cell carcinoma cell line (HSC-1) cells were cultivated with recombinant human IFN-gamma (rIFN-gamma) and IL-1 levels were measured by ELISA. The effects of antipsoriatic agents such as hydrocortisone (HC), cyclosporin A (CsA), 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] and its analogue MC903 on IL-1 production by keratinocytes were also investigated. IL-1 release by both NHK and HSC-1 cells was accelerated by stimulation with rIFN-gamma dose-dependently, although IL-1 alpha was released only transiently by rIFN-gamma-stimulated NHKs in serum-free keratinocyte growth medium containing HC. Antihuman IFN-gamma antibody inhibited IL-1 alpha release by HSC-1 cells stimulated with rIFN-gamma, suggesting that IL-1 alpha release from keratinocytes is upregulated by IFN-gamma. HC (5 micrograms/ml), 1,25(OH)2D3 (10(-6) M) and MC903 (10(-6) M), but not CsA (5 micrograms/ml), inhibited IL-1 alpha production by HSC-1 cells stimulated with 100 U/ml of rIFN-gamma.(ABSTRACT TRUNCATED AT 250 WORDS)

Feasibility of in vitro culturing of lesional psoriatic keratinocytes in medium containing high calcium concentrations

Lesional psoriatic keratinocyte (LPK) culture is considered to be difficult under high-Ca2+ conditions in the absence of special proliferative agents. Using a permeable collagen membrane, we obtained a culture of LPKs under high-Ca2+ conditions without any special proliferative agents. Single-cell suspensions were prepared from the epidermis of chronic psoriatic plaques. Cells were inoculated on the collagen membrane suspended slightly above the bottom of a Petri dish. We used a culture medium of Eagle's MEM containing 10% fetal calf serum. LPKs attached to the membrane 12 h after inoculation and gradually spread. They reached a confluent state by the 10th day of culture. We measured the concentrations of TGF alpha and IL-6 in the medium of LPKs, and compared these with the concentrations in normal keratinocyte (NK) cultures. Significantly increased secretion of TGF alpha by LPKs was observed during the initial phase but this secretion subsequently decreased. Concentrations of IL-6 were below the detectable level in both of NKs and LPKs throughout the observation period. Our results demonstrate that cultured LPKs under high-Ca2+ conditions secrete a larger amount of TGF alpha but not IL-6. Our cell culture system, which allows LPKs to spread and stratify, contributes to the study of the pathogenesis of psoriasis.

Differential Cell Surface Distribution of Adhesion Molecules Demonstrated by Immuno‐Scanning Electron Microscopy

Scanning electron microscopy with immuno-gold labeling revealed that epidermal keratinocytes expressed ICAM-1 and HLA-DR molecules on their surfaces in patterns that differed in mycosis fungoides (MF) and lichenoid reaction (LR). ICAM-1 molecules, visualized as deposits of gold particles, were present as clusters adjacent to the junctions interconnecting the keratinocytes of MF lesions. LFA-1 molecules were seen as granules on the surfaces of all infiltrates, most of which also expressed ICAM-1. HLA-DR molecules were seen continuously along the borders of the individual keratinocytes. In LR, ICAM-1 and HLA-DR were expressed only sparsely on the undersurface of the epidermis, whereas the infiltrates expressed LFA-1 molecules on their surfaces. These findings may explain the differing histological features of MF and LR: ICAM-1 molecules present on the intercellular junctions of MF epidermis lead the LFA-1-bearing cells to migrate into the interspaces of the keratinocytes, thus producing "epidermotropism". These cells aggregate by means of co-expressed ICAM-1 to thus produce the appearance of a "microabscess". In LR, on the other hand, the minimal expression of ICAM-1 on the epidermal undersurface leaves most infiltrates within the dermis, thus producing a "band-like infiltrate" beneath the epidermis.

Immunohistochemical detection of p53 protein in cutaneous lesions from transplant recipients harbouring human papillomavirus DNA.

Human papillomaviruses (HPV) are thought to be involved in the malignant evolution of cutaneous lesions from transplant recipients. As E6 proteins from potentially oncogenic HPV types degrade p53 tumour suppressor gene product in vitro, we analysed p53 protein status in benign, premalignant and malignant skin lesions from grafted patients, to determine whether HPV may interfere with p53 function. With immunohistochemistry, p53 protein accumulation was detected in 70% of skin lesions from grafted patients. p53 immunoreactivity was confined to basal keratinocytes in benign lesions (warts, condylomas), while suprabasal keratinocytes were also stained in premalignant and malignant skin lesions (precancerous keratoses, squamous cell carcinomas). Multiple HPV carriage was detected with in situ hybridization in benign and malignant skin lesions from transplant recipients: low risk HPV types 1, 2, 6, 11 and potentially oncogenic HPV types 5, 16, 18 were frequently found. There was no clear correlation between p53 detection and the presence of the HPV types under study. The frequent detection of p53 protein in cutaneous lesions from grafted patients is suggestive of p53 protein accumulation interfering with normal function. Our results may reflect the presence of mutated p53 proteins due to the mutagenic effect of ultra-violet (UV), or wild-type p53 protein accumulation in response to UV-induced DNA damage, or may be produced by the interaction with HPV-encoded E6 proteins.

Expression of class II major histocompatibility antigens by keratinocytes in cutaneous T cell lymphoma.

Expression of various class II MHC antigens by lesional keratinocytes may play an important role in the pathophysiology of a wide variety of human dermatoses including cutaneous T cell lymphoma (CTCL). Nevertheless, there is relatively little information available concerning the concurrent expression of HLA-DR, -DP, and -DQ class II MHC antigens in CTCL. Therefore, our aim in this study was to determine the prevalence, localization, extent, temporal sequence, and consistency of class II MHC antigen expression by lesional keratinocytes in CTCL. We used a semiquantitative immunohistologic analysis to analyze HLA-DR, -DP, and -DQ expression by lesional keratinocytes in 66 skin biopsies obtained from 39 patients with CTCL. Class II MHC antigen expression by keratinocytes was observed in 77% of cases. Expression was detected on the cytoplasmic membrane and within the cytoplasm. It varied among cases from focal to confluent. There was a hierarchy of antigen expression in terms of both extent and time course. HLA-DR was expressed first and most extensively, followed by HLA-DP and then HLA-DQ. Comparative studies of multiple serial or concurrent active lesions from 13 cases indicated that the overall pattern and extent of antigen expression was relatively constant within individual patients. There was no apparent correlation between class II MHC antigen expression and the clinical stage of disease, the type of CTCL skin lesion, or the overall density of the lesional T cell infiltrate. The hierarchy of keratinocyte class II MHC antigen expression observed in this study paralleled that noted in earlier studies of cultured keratinocytes exposed to recombinant interferon-gamma in vitro. This suggests that lesional cytokine levels may be the critical factor governing class II MHC antigen expression by lesional keratinocytes in CTCL.

Expression of thrombospondin-1 (TSP1) and its receptor (CD36) in healthy and diseased human skin.

In the present study, an analysis was made of the expression pattern of thrombospondin-1 (TSP1) and its receptor (CD36) in skin biopsies obtained from healthy volunteers and from patients with lichen planus, lupus erythematosus, cutaneous T-cell lymphoma and psoriasis vulgaris. Using monoclonal antibodies against TSP1 in biopsies from the healthy volunteers and from both clinically involved and uninvolved skin of the patients, a specific peroxidase-positive reaction was detected around the sweat glands in the dermis. In all cases investigated, the CD36-positive lesional keratinocytes remained TSP1-negative. These findings favour the hypothesis that CD36-positive keratinocytes might have some functional relevance via oxidized low-density lipoprotein and/or collagen fibrils, without any connection with TSP1.

Induction of proliferating cell nuclear antigen in differentiated keratinocytes of human papillomavirus-infected lesions

The expression of proliferating cell nuclear antigen (PCNA) was studied in human papillomavirus (HPV)-infected, benign and malignant lesions of the genital tract and larynx using immunocytochemical staining of formalin-fixed clinical specimens. We observed the induction of PCNA in squamous carcinomas and adenocarcinomas, as has been demonstrated with other malignancies. In addition, the differentiated keratinocytes of the upper spinous cells and granulocytes in condylomata acuminata and low-grade intraepithelial neoplasias showed a consistent induction of PCNA compared with the normal squamous epithelium, in which only some of the parabasal and basal cells were positive. This reactivation of PCNA synthesis correlated with the presence of high copy numbers of HPV DNA and was independent of the oncogenic risk potential of the infecting HPV genotype. We postulate that HPV gene products induce the expression of PCNA and other components of the host DNA replication machinery in differentiated cells of squamous lesions to facilitate vegetative viral replication.

Induction of Intercellular Adhesion Molecule‐1 and Adherence of HTLV‐1‐Infected T‐cells to Cultured Keratinocytes

Cutaneous lesions of T-cell proliferative disorders are characterized by epidermotropic infiltration of the neoplastic cells and expression of intercellular adhesion molecule-1 (ICAM-1) and HLA-DR by lesional keratinocytes. Using cloned HTLV-1-infected T-cells obtained from patients with adult T-cell leukemia (ATL), we have studied immunobiological activities of cytokines released from the T-cell lines and their ability to adhere to cultured keratinocytes. Three out of the five CD-4-positive, HTLV-1-infected T-cell clones secreted both IFN-gamma and IL-4, similar to murine Th0 clones. The other two clones did not produce such cytokines. ICAM-1 and HLA-DR molecules were induced on cultured normal human keratinocytes and organ-cultured skin specimens by co-cultivation with IFN-gamma-producing T-cell clones or their culture supernatants. Induction of both molecules was markedly inhibited by pretreatment of the supernatants with excess amounts of anti-IFN-gamma monoclonal antibody. The number of cells adherent to the normal cultured keratinocytes was greater in the IFN-gamma-producing clones than in the non-producing ones. These data suggest that some HTLV-1-infected clones produce cytokines, including IFN-gamma, which in turn induce ICAM-1 on keratinocytes, thereby enhancing the ability of the T-cell clones to adhere to the keratinocytes.

Cellular adhesion antigen modulation in purpura pigmentosa chronica

Purpura pigmentosa chronica is an inflammatory skin disorder probably caused by an allergic reaction. Delayed-type hypersensitivity or immunocomplex vasculitis has been considered as a possible mechanism. Detailed analysis of cell adhesion molecule (CAM) modulation may give further insights into the pathogenesis and underlying immune reaction of this disease. By immunohistochemical techniques we investigated the in situ expression of integrins, selectins, and CAMs of the immunoglobulin superfamily. Infiltrating lymphocytes expressed LFA-1, LFA-2, VLA-4, and VLA-5, whereas some of the macrophages were also positive for p150/95 and MAC-1. VLA-1 was found on lymphocytes near the basement membrane of the epidermis. Compared with uninvolved or healthy skin endothelial cells showed upregulation of ICAM-1, VCAM-1, and, focally, E-selectin. Some fibroblasts were positive for ICAM-1. ICAM-1 was also upregulated on lesional keratinocytes that also expressed alpha 2, alpha 3, and alpha 6 integrin chains on basal and suprabasal epidermal layers. Our findings demonstrate characteristic modifications in the expression of CAMs in purpura pigmentosa chronica and indicate the involvement of the epidermis in this disease. This modulation shows close parallels to those described for chronic delayed-type immune reactions of the skin.

Analysis of HLA‐DR expression on keratinocytes in cervical neoplasia

We have investigated the expression in vivo and in vitro of HLA-DR in pre-invasive squamous-cell neoplasia of the uterine cervix. Immunohistochemistry of cervical biopsies demonstrated HLA-DR expression by cervical keratinocytes in 50% of cases of high-grade squamous intra-epithelial neoplasia, although the molecule was rarely expressed in low-grade squamous intra-epithelial neoplasia and was absent from normal ectocervical cells. HLA-DR-positive high-grade lesions were associated with significantly greater numbers of T lymphocytes in the immediately sub-epithelial stroma than were the HLA-DR-negative high-grade lesions. In vitro HLA-DR expression was absent from normal ectocervical epithelium, and from the HPV type 16 containing cell lines W12 (representing low-grade squamous intra-epithelial neoplasia) and CaSki and SiHa (each representing high-grade squamous intra-epithelial neoplasia), both in monolayer and in organotypic raft culture. HLA-DR expression was induced in all cell types following recombinant interferon gamma treatment. Our data suggest that the expression of HLA-DR by keratinocytes in some high-grade cervical lesions in vivo may be due to local induction of the molecule by pro-inflammatory cytokines released by immunocompetent cells. The functional significance of HLA-DR positivity in enabling an effective host immune response to neoplastic cervical keratinocytes remains unclear.

Overexpression of p53 Tumor Suppressor Protein in Porokeratosis

p53 is a tumor suppressor nucleoprotein. Mutations of the p53 gene have been found in a variety of malignant neoplasms. Wild-type p53 has a short half-life, possibly only 20 to 30 minutes, and is not present in the nucleus at levels that are detectable with routine immunohistochemical techniques. Mutant p53 has a longer half-life, and is readily detectable with immunoperoxidase staining. We studied 17 specimens from patients with either porokeratosis of Mibelli or actinic porokeratosis, using immunoperoxidase staining with an antibody directed against the p53. There was staining of lesional keratinocyte nuclei in 16 of 17 specimens, limited in most cases to the zone between cornoid lamellae. Staining for proliferating cell nuclear antigen was increased above background levels in only six of 13 specimens. The finding of p53 immunoperoxidase staining in porokeratosis suggests genetic mutation, as occurs in other cutaneous keratinocytic neoplasms, and the lack of corresponding proliferating cell nuclear antigen expression in many specimens indicates that p53 overexpression is not simply a reflection of increased cellular proliferation.

Expression of the myelomonocytic antigens CD36 and L1 by keratinocytes in squamous intraepithelial lesions of the cervix

The keratinocytes in squamous intraepithelial lesions (SILs) of the cervix show altered expression of a number of molecules involved both in the control of growth and differentiation and in cell surface interactions, particularly with components of the immune system. We have used tissue biopsies and in vitro model systems to investigate the expression in SILs of the molecules CD36 and L1, which are predominantly expressed by myelomonocytic cells but which also have functional roles in keratinocyte biology. Whereas the L1 protein (defined by the monoclonal antibody Mac387) was expressed by suprabasal and superficial cells in 12 of 12 cases of normal cervix (NCx) and in 14 of 14 cases of low-grade SILs (LG-SILs), in two of 16 cases of high-grade SILs (HG-SILs) it was entirely absent and in the remainder it was restricted to the most superficial layers. When an arbitrary grading scale was applied, L1 expression in HG-SILs proved to be significantly lower than in LG-SILs ( P < .01) or in cases of NCx ( P < .01). CD36 was expressed by superficial cells in four of 12 cases of NCx, in six of 14 LG-SILs, and none of 16 cases of HG-SILs (when graded, LG-SILs ν HG-SILs = P < .05). The mechanisms underlying the expression of both molecules were investigated by growth in organotypic tissue culture of normal ectocervical epithelium and the cervical keratinocyte cell lines W12 (a model for LG-SILs) and CaSki and SiHa (models for HG-SILs). L1 was diffusely expressed by NCx cells and the W12 cell line, although its expression in the CaSki and SiHa cell lines was much more irregular and restricted. CD36 was occasionally present on the surface of superficial NCx and W12 cells, but was absent from CaSki and SiHa cells. Neither molecule could be induced by treatment of the cells with interferon-gamma. These data suggest that the expression of CD36 and L1 by cervical keratinocytes is related to their differentiation status rather than representing an effect of exogenous factors, such as those released by the immune cell infiltrate associated with SILs. CD36 may function as an immunoregulatory molecule on cervical keratinocytes in SILs, while L1 is more likely to be involved in the intracellular regulation of cell proliferation and maturation.

Expression of Immune Associated Surface Antigens of Keratinocytes in Human Papillomavirus-Derived Lesions

The expression of immune associated surface antigens of keratinocytes was studied in human papillomavirus (HPV) derived lesions in order to determine whether HPV types have a regulatory role in the pathogenesis of papillomas. A series of cutaneous and mucosal lesions were immunolabeled with monoclonal antibodies to the major histocompatibility complex class 1 (β2-microglobulin) and 2 (HLA-DR antigens), intercellular adhesion molecule (ICAM-1) and glycoprotein CD36 (OKM5) as well as CD1a (Langerhans cells), CD4, CD8 (T cells) and CD11a (LFA1 antigen). Testing for the presence of HPV was carried Out by in situ hybridization with biotinylated probes for viral DNA detection and typing. We observed a drastic reduction or a loss of β2-microglobulin by keratinocytes from cutaneous lesions in correlation with the disappearance of Langerhans cells. Only mild alterations were observed in mucosal lesions. HLA-DR expressed by keratinocytes was only detected in condylomas and laryngeal papillomas and was usually associated with a dense inflammatory reaction. This HLA-DR expression may be correlated with an up-regulation of ICAM-1 and the presence of LFA1 positive leukocytes, mainly of CD8 phenotype, in the epithelium. CD36 was detected on differentiated keratinocytes of all lesions; its expression seems related to the proliferation state of the lesions and probably does not represent an immune marker. The different reactivity patterns observed in cutaneous and mucosal lesions may reflect: 1. different roles for mucosal and cutaneous HPV types in the induction of immunoregulatory surface antigens of keratinocytes, or 2. the changing nature of the cytokines released by mononuclear cells and infected keratinocytes in these lesions.

MCP-1 mRNA Expression in Basal Keratinocytes of Psoriatic Lesions

In addition to hyperproliferation of keratinocytes, psoriasis is characterized by pronounced leukocytic infiltration. In contrast to the epidermal localization of neutrophils and T lymphocytes, macrophages are almost exclusively restricted to the dermal compartment. By immunohistologic analysis, these dermal macrophages were mainly encountered in the papillary dermis and arranged along the rete ridges in close proximity to proliferating keratinocytes. Monocyte chemoattractant protein (MCP-1) anti-sense RNA probes yielded abundant signals over the proliferating basal keratinocytes of the tips of the rete ridges, and, to a lesser extent, in cells in the papillae. Thus, the strongest MCP-1 message in psoriatic lesions is found above the dermal-epidermal junction and this may explain the characteristic sub-basal distribution of dermal macrophages. These results suggest that MCP-1 is important in regulating the interaction between proliferating keratinocytes and dermal macrophages in psoriasis pathogenesis.

Lesional psoriatic keratinocytes can be cultured on a permeable collagen membrane in a normal Ca 2+ condition

Lesional psoriatic keratinocytes can be cultured on a permeable collagen membrane in a normal Ca 2+ condition

Increased in vitro expression of beta 2-adrenoceptors in differentiating lesional keratinocytes of vitiligo patients.

Keratinocytes were established in serum-free culture medium from lesional and nonlesional skin of a patient with vitiligo (skin type III) and from an age-matched healthy control subject. Both differentiating and undifferentiated cells were examined for the presence of beta 2-adrenoceptors in culture medium containing either low (0.1 x 10(-3) M) or high (1.5 x 10(-3) M) calcium concentrations. Binding experiments were performed with saturating levels of radiolabeled (--)-[3H] CGP 12177, a nonselective beta-adrenergic antagonist. Controls for nonspecific binding were determined by the addition of the beta-adrenergic antagonist, propranolol (5 mumol), before the introduction of (--)-[3H] CGP 12177 to cell cultures. Undifferentiated keratinocytes yielded the highest expression of beta 2-adrenoceptors, whereas differentiating keratinocytes grown in medium with a low calcium concentration (0.1 x 10(-3) M) had a significantly lower expression of receptors with the exception of vitiliginous cells, which retained high densities of receptors, similar to undifferentiated cells. In addition, these vitiliginous keratinocytes showed a defect in 45calcium uptake. In contrast, differentiated keratinocytes from all three cell strains, grown in medium containing a high calcium concentration (1.5 x 10(-3) M) revealed a significantly lower receptor density compared to undifferentiated cells. This finding identified the importance of the extracellular calcium concentration in the expression of beta 2-adrenoceptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Leukemic T Cells from Patients with Cutaneous T-Cell Lymphoma Demonstrate Enhanced Activation Through CDw60, CD2, and CD28 Relative to Activation Through the T-Cell Antigen Receptor Complex

Antigen-dependent activation of T cells occurs through the T-cell antigen-receptor complex (TCR/CD3). Antigen-independent T-cell activation may occur through the surface molecules CDw60, CD2, and CD28. We wished to determine whether these antigen-independent T-cell-activation pathways could be involved in proliferation of leukemic T cells from patients with cutaneous T-cell lymphoma (CTCL). Whereas CDw60 was only expressed on 28% +/- 7% (mean +/- SEM) of blood T cells obtained from healthy control subjects (n = 4), CDw60 was expressed on 94% +/- 3% of blood T cells obtained from patients with CTCL (n = 4). Dual color immunofluorescence microscopy of the T-cell infiltrate in involved skin of these patients demonstrated that almost 100% of the T cells expressed CDw60. Not only did T cells in the patients with CTCL express CDw60, but triggering of the T cells with anti-CDw60 resulted in enhanced proliferation relative to anti-TCR/CD3 and mitogenic lectins. Other antigen-independent pathways also appeared highly active in the T cells from patients with CTCL because enhanced proliferation relative to anti-TCR/CD3 or mitogenic lectins was found when anti-CD2 or anti-CD28 plus phorbol ester was used as stimulant. Despite the brisk proliferation induced by anti-CDw60, anti-CD2, or anti-CD28, T cells from the patients did not produce detectable amounts of gamma-interferon. The inability to produce gamma-interferon correlates with our finding of absent (n = 3) or weak (n = 1) intercellular adhesion molecule-1 expression in the lesional keratinocytes in these patients. In conclusion, T cells of patients with CTCL demonstrate elevated expression of a T-cell-independent signaling molecule CDw60 and respond to antigen-independent activating signals.