Elevated serum eosinophil cationic protein and transforming growth factor-α levels in a patient with pemphigus vegetans.

Pemphigus vegetans (PVeg) is a rare variant of pemphigus, characterized by vegetating lesions mainly with antidesmoglein 3 antibodies. However, the pathomechanisms for PVeg is still unknown. We present a patient with PVeg mainly associated with antidesmocollin (Dsc)3 antibodies, who originally developed pemphigus foliaceus. Serum levels of eosinophil cationic protein and transforming growth factor (TGF)-α increased at the onset of PVeg in this patient. Thus, TGF-α might be involved in the formation of vegetating lesions in PVeg.

Induction of humoral and cellular immune response to hepatitis B virus (HBV) vaccine can be upregulated by CpG oligonucleotides complexed with Dectin-1 ligand.

A persistent hepatitis B virus (HBV) infection is characterized by a lack of or a weak immune response to HBV, which may be reflective of tolerance to HBV. Efficient induction of HBV-specific immune response leads to the clearance of HBV in patients with a chronic HBV infection. CpG oligodeoxynucleotides (ODN) has a powerful adjuvant effect in HBV vaccination. A recent report demonstrated that the immunization by B/K CpG ODN (K3) wrapped by the nonagonistic Dectin-1 ligand, schizophyllan (SPG), namely K3-SPG, was more effective in the induction of antigen-specific immune response than that by K3. In this study, we examined the efficacy of K3-SPG as a HBV vaccine adjuvant. Wild-type (WT) mice and HBV transgenic (HBV-Tg) mice were subcutaneously immunized with hepatitis B surface antigen (HBsAg) alone, HBsAg and K3, or HBsAg and K3-SPG. The vaccination with HBsAg and K3-SPG significantly enhanced humoral and cellular immune response to HBV antigen compared to the other vaccinations in WT and HBV-Tg mice. K3-SPG induced the accumulation of dendritic cells (DCs) into draining lymph node and the activation of DCs. The expression of cytokines and chemokines related to Th1 and Th2 responses was upregulated after the vaccination including with K3-SPG. In conclusion, these results indicated that the vaccination using K3-SPG may overcome tolerance even in patients with chronic HBV infection.

Risk factors for infantile atopic dermatitis and recurrent wheezing.

BACKGROUND: The pathogenic mechanisms of atopic dermatitis (AD) and recurrent wheezing (RW) during infancy are not fully understood. OBJECTIVE: We evaluated immunological markers associated with AD and RW during infancy. METHODS: We followed a cohort (n = 314) from birth to 14 months of age. Some of the participants underwent a physical examination and blood test at 6 and 14 months of age. Univariate and multivariate logistic regression analysis and receiver operating characteristic curve analysis were performed to find which immunological markers could be risk factors for AD and RW. RESULTS: Of 16 immunological markers found in cord blood, only immunoglobulin (Ig) E was associated with AD at 6 months of age (adjusted OR [aOR], 1.607). None of the markers was associated with AD or RW at 14 months of age. Of 23 immunological markers at 6 months of age, total IgE (aOR, 1.018) and sensitization to egg white (aOR, 23.246) were associated with AD at 14 months of age. Phytohemagglutinin (PHA)-induced production of interleukin (IL) 4 from peripheral blood mononuclear cells (PBMCs) (aOR, 1.043) was associated with RW at 14 months of age. CONCLUSION: Cord blood IgE was a risk factor for AD at 6 months of age. Total IgE and sensitization to egg white at 6 months of age were risk factors for AD at 14 months of age. PHA-induced IL-4 production in PBMCs at 6 months of age was a risk factor for RW at 14 months of age.

Effect of long-term physical exercise of peripheral nerve: comparison of nerve conduction study and ultrasonography.

AIM: The aim of this study was to assess the effects of long-term physical exercise on peripheral nerve using both nerve conduction study (NCS) and ultrasonography (US). METHODS: The authors measured nerve conduction study and ultrasonography in 15 male (mean, 20±1.5 years) handball players and 13 male (mean, 21.3±1.9 years) control subjects. Cross-sectional area of the median nerve was evaluated using ultrasonography at the carpal tunnel and 6 cm proximal to the wrist, and the ulnar nerve at 6 cm proximal to the wrist crease, 2 cm proximal to the medial epicondyle, the epicondyle, and 2 cm distal to epicondyle. RESULTS: US shows significantly increased cross-sectional area of both median and ulnar nerve in the players compared with that in the controls, and the latency times in both nerves were significantly delayed in the players compared with that in the controls. Cross-sectional area of the median nerve showed a significant correlation with latency (r=0.330, P<0.01). CONCLUSION: This study suggests that the players have a tendency toward having both median and ulnar motor nerve damage in the wrist or elbow region although they are asymptomatic.

Autoerythrocyte sensitization syndrome with vertigo and hemilateral auditory impairment.

Autoerythrocyte sensitization syndrome (AES) is characterized by recurrent, painful purpura or ecchymosis. Testing for the reappearance of lesions after injection of the patient's own erythrocytes is usually useful for the diagnosis of AES, but the significance of this test is still controversial. As the lesions often appear in patients with psychiatric disorders, mental factors such as depression and stress are considered to be involved in the occurrence and exacerbation of AES. We report a 28-year-old woman who presented recurrent episodes of painful purpura with vertigo and hemilateral auditory impairment after difficulties at her workplace. After the diagnosis of AES, she was referred for psychiatric counselling, after which the symptoms disappeared. These findings suggest that treatment for psychological disorders is important in patients with AES.

Antineutrophil cytoplasmic antibody-associated vasculitis with oculomotor nerve palsy.

We report a patient with antineutrophil cytoplasmic antibody-associated vasculitis with oculomotor nerve palsy. The patient presented with a high fever, diplopia, blepharoptosis and impairment of ocular movement of the left eye except for lateral gaze. Multiple erythematous and livedoid lesions were observed on the forehead, both cheeks and both legs. Laboratory examination showed positive results for myeloperoxidase antineutrophil cytoplasmic antibodies. Skin biopsy revealed leucocytoclastic vasculitis of the small arteries in the lower dermis. The patient was successfully treated with systemic corticosteroids.

Cytokine profile during the clinical course of toxic shock syndrome.

Toxic shock syndrome (TSS) is an acute febrile disease with multiple organ involvement caused by massive and rapid release of cytokines induced by staphylococcal exotoxins. However, the precise cytokine profile is still undefined in clinical cases. We measured serum cytokine concentrations in a patient who developed TSS after a caesarean section. Measurements were taken on admission and several times during the course of the disease. Methicillin-resistant Staphylococcus aureus producing TSS toxin-1 and staphylococcal enterotoxin C was detected in the lochia and venous blood. Serum interleukin (IL)-6 level was markedly increased on admission, and IL-10, tumour necrosis factor-alpha, and interferon-gamma levels were also raised. These cytokine levels rapidly returned to normal levels. In contrast, IL-1beta and IL-2 were below the analytical sensitivity threshold throughout the course. Our data and other previous case reports indicate that a marked increase in IL-6 concentration could be a clinical marker of TSS onset.

Acute heart failure associated with human parvovirus B19 infection.

We report a patient with acute heart failure due to human parvovirus B19 infection. The patient was a 36-year-old man with polyarthralgia, fatigue and swelling of his upper eyelids and all four limbs. These symptoms disappeared, but 5 days after the first consultation, the patient presented with severe exertional dyspnoea, chest pain and swelling of his whole body. Erythema was observed on the skin of hands, fingers and abdomen. Pleural and pericardial effusion, ascites and hepatosplenomegaly were detected. Laboratory examination showed positive results for anti-human parvovirus B19 IgM and B19 DNA in the serum. A diagnosis of acute heart failure by pericarditis caused by B19 was made. This case report suggests that B19 should be considered as a cause of acute heart failure through acute pericarditis.

Stimulatory effects of lipoprotein(a) and low-density lipoprotein on human umbilical vein endothelial cell migration and proliferation are partially mediated by fibroblast growth factor-2.

We previously reported a transient increase in plasma lipoprotein(a) (Lp(a)) concentrations following acute myocardial infarction and surgical operations, and demonstrated Lp(a) accumulation in healing tissues. In the present study, the stimulatory effect of Lp(a) on migration and proliferation of human umbilical vein endothelial cells (HUVEC) was assessed by quantitative assay methods and compared it with that of LDL. Lp(a) stimulated both migration and proliferation of HUVEC in a dose-dependent manner and the stimulatory activities for migration and proliferation were two times higher than those of LDL in terms of moles of apoB. In addition, this stimulatory activity of Lp(a) was not affected by the difference of Lp(a) phenotype. Although each neutralizing antibody to hepatocyte growth factor (HGF), platelet-derived growth factor (PDGF) and interleukin-1beta (IL-1beta) had no further effect on migration and proliferation of HUVEC treated with Lp(a), only antibody to fibroblast growth factor-2 (FGF-2) partially suppressed them. Moreover, pertussis toxin, which inhibits FGF-2-stimulated endothelial cell movement, also partially suppressed Lp(a)-induced HUVEC migration. FGF-2 concentrations in the medium of HUVEC treated with Lp(a) were constant in spite of the increase in FGF-2 mRNA levels in HUVEC. Taken together, it is suggest that Lp(a) stimulates HUVEC migration and proliferation, which is mediated, at least in part, by FGF-2 and may promote the angiogenesis during wound healing.

Tumor necrosis factor-alpha (TNF-alpha) plays a protective role in acute viralmyocarditis in mice: A study using mice lacking TNF-alpha.

BACKGROUND: It has been reported that tumor necrosis factor-alpha (TNF-alpha) is expressed in the heart with viral myocarditis and that its expression aggravates the condition. The pathophysiological effects of TNF-alpha on viral myocarditis, however, have not been fully elucidated. METHODS AND RESULTS: To investigate the role of TNF-alpha in the progression of viral myocarditis, we used TNF-alpha gene-deficient mice (TNF-alpha(-/-)) and induced acute myocarditis by infection with encephalomyocarditis virus (EMCV). The survival rate of TNF-alpha(-/-) mice after EMCV infection was significantly lower than that of TNF-alpha(+/+) mice (0% versus 67% on day 14). Injection of recombinant human TNF-alpha (0.2 to 4.0 microg/mouse IV) improved the survival of TNF-alpha(-/-) mice in a dose-dependent manner, indicating that TNF-alpha is essential for protection against viral myocarditis. The levels of viral titer and viral genomic RNA of EMCV in the myocardium were significantly higher in TNF-alpha(-/-) than in TNF-alpha(+/+) mice. Histopathological examination showed that the inflammatory changes of the myocardium were less marked in TNF-alpha(-/-) than in TNF-alpha(+/+) mice. Immunohistochemical analysis revealed that the levels of immunoreactivity of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in the myocardium were decreased in TNF-alpha(-/-) mice compared with TNF-alpha(+/+) mice. CONCLUSIONS: These observations suggested that TNF-alpha is necessary for adhesion molecule expression and to recruit leukocytes to inflammatory sites, and thus, the lack of this cytokine resulted in failure of elimination of infectious agents. We concluded that TNF-alpha plays a protective role in the acute stage of viral myocarditis.

Plasma Fas ligand, an inducer of apoptosis, and plasma soluble Fas, an inhibitor of apoptosis, in patients with chronic congestive heart failure.

OBJECTIVES: This study sought to examine plasma levels of soluble Fas/APO-1 receptor (sFas), an inhibitor of apoptosis, and soluble Fas ligand (sFas-L), an inducer of apoptosis, and their relation to each other and to other clinical variables, such as New York Heart Association functional class, tumor necrosis factor (TNF) and interleukin-6 (IL-6) in congestive heart failure (CHF). BACKGROUND: It has been recently reported that apoptotic cell death occurs in myocytes of dogs with CHF. Hypoxia is frequently seen in advanced CHF and can stimulate Fas/APO-1 receptors (Fas) to induce apoptosis in cultured myocytes. Fas and Fas ligand (Fas-L) are cell-surface proteins and representative apoptosis-signaling molecules. Fas on the cell membrane induces apoptosis when it binds Fas-L or sFas-L. However, plasma sFas, a molecule lacking the transmembrane domain of Fas, blocks apoptosis by inhibiting binding between Fas and Fas-L or sFas-L on the cell membrane. At present, it is unknown whether plasma sFas-L and plasma sFas increase in the presence of cardiac disease. METHODS: The study included 70 patients (mean [+/-SEM] age 65 +/- 2 years, range 21 to 93) with chronic CHF (coronary artery disease in 28, dilated cardiomyopathy in 27, valvular heart disease in 15) and 62 age- and gender-matched normal control subjects. Plasma levels of sFas, sFas-L, TNF-alpha and IL-6 were measured by enzyme-linked immunosorbent assays using monoclonal anti-human antibodies. RESULTS: There was no significant difference in sFas-L levels between normal subjects and patients in functional classes I to IV; however, sFas increased with severity of functional classification, independent of the underlying disease. sFas levels were significantly higher even in patients in functional class II than in normal subjects and those in functional class I, and were highest in patients in functional class IV (normal subjects; 2.2 +/- 0.1 ng/ml; functional class I: 2.2 +/- 0.2 ng/ml; functional class II: 3.1 +/- 0.2 ng/ml; functional class III: 3.9 +/- 0.3 ng/ml; functional class IV: 5.1 +/- 0.6 ng/ml). Plasma sFas levels were significantly higher in patients with elevated pulmonary artery wedge pressure and a decresed cardiac index than in those with values in the normal range. In patients in functional class IV, there was no significant difference in plasma sFas levels between the survivors and non-survivors during 6-month follow-up. However, plasma levels of sFas tended to decrease in nine patients with clinical improvement (baseline sFas: 5.2 +/- 0.8 ng/ml; 6-month sFas: 4.3 +/- 0.5 ng/ml, p = 0.07) but were similar in patients with no change in functional class. TNF-alpha and IL-6 were increased significantly only in patients in functional class IV, as previously reported, but were not related to sFas. CONCLUSIONS: We found elevated levels of plasma sFas and no increase in plasma sFas-L in human CHF. The increase in sFas may play an important role in the pathophysiologic mechanisms of CHF.

Pemphigus IgG activates and translocates protein kinase C from the cytosol to the particulate/cytoskeleton fractions in human keratinocytes.

We have demonstrated previously that pemphigus vulgaris (PV)-IgG induces activation of phospholipase C (PLC), production of inositol 1,4,5-trisphosphate, and a rapid transient increase in [Ca2+]i in cultured human keratinocytes, leading to secretion of plasminogen activator and cell-cell detachment in cell culture. In the current study, to examine the involvement of protein kinase C (PKC) in the mechanism of blister formation in PV, we studied the PV-IgG-induced translocation of PKC isozymes from the cytosol to the particulate/cytoskeleton (p/c) fractions and the activation of PKC in human keratinocytes. Cells cultured in Eagle's minimum essential medium were incubated with PV-IgGs for 30 s, 1 min, 5 min, or 30 min. PV-IgG binding to the cell surface antigen (desmoglein III) induced translocation of PKC-alpha from the cytosol to the p/c fractions within 30 s, with a peak at 1 min that lasted at least 30 min. PKC-delta also was translocated within 1 min and reached a peak at 5 min but was reduced to basal levels at 30 min. Alternatively, PKC-eta translocation to the p/c fraction was induced slowly, taking more than 5 min, and was reduced to approximately half-maximum at 30 min, whereas PKC-zeta translocation reached a maximum at 30 s, rapidly returning to baseline by 5 min after PV-IgG stimulation. The total PKC activity in the p/c fraction also was increased after PV-IgG exposure, peaked at 1 min, and was sustained for at least 30 min. These findings suggest that a unique activation profile of PKC isomers may be involved in mediating the intracellular signaling events induced by PV-IgG binding to desmoglein III in cultured human keratinocytes.

Increased protein kinase C activity in fibroblast membranes from psoriatic patients.

The activity of phospholipid/Ca2+-dependent protein kinase (PKc) was measured in the membrane and cytosolic fractions of normal and psoriatic human fibroblasts. The psoriatic fibroblasts displayed higher membrane-associated PKc activity than normal cells. In contrast, no significant difference in PKc activities was observed in cytosolic fractions from normal and psoriatic fibroblasts. These data suggest that PKc is preferentially associated with the membrane in psoriatic fibroblasts and that such elevated PKc activity in membranes may play a role in the pathogenesis of this disease.

Involvement of phospholipase D in ganglioside GQ1b-induced biphasic diacylglycerol production in human keratinocytes.

Ganglioside IV3 (NeuAc)2, II3 (NeuAc)2-GgOse4Cer (GQ1b), which induces terminal differentiation in keratinocytes, was previously found to enhance the mass content of inositol 1,4,5-trisphosphate and intracellular calcium concentration ([Ca++]i), peaking at 30 seconds. In the present study, the biphasic accumulation of 1,2 diacylglycerol, i.e., the first transient and the second sustained phase, was observed in cultured human keratinocytes stimulated by GQ1b. On the other hand, II3 NeuAc-LacCer (GM3), which inhibits keratinocyte proliferation without inducing differentiation, did not cause diacylglycerol formation. Phosphatidylethanol, produced by transphosphatidylation and a potential marker for phospholipase D activity, was produced by the exposure to GQ1b in the presence of ethanol. The second sustained phase of diacylglycerol was repressed by ethanol, indicating that the diacylglycerol-formation pathway via phospholipase D followed by phosphatidic acid phosphohydrolase would in part account for the second diacylglycerol phase. Furthermore, this second phase of GQ1b-induced diacylglycerol generation was reduced by pretreatment with propranolol, an inhibitor of phosphatidic acid phosphohydrolase. In addition, the levels of [3H]choline, a direct metabolite of the phospholipase D pathway, were elevated within 1 min after GQ1b addition and then sustained for at least 20 min. Taken together, the results suggest that the phospholipase D pathway may contribute to the second phase of diacylglycerol formation, which might be involved in differentiation.

Pharmacologic evidence for involvement of phospholipase C in pemphigus IgG-induced inositol 1,4,5-trisphosphate generation, intracellular calcium increase, and plasminogen activator secretion in DJM-1 cells, a squamous cell carcinoma line.

The precise mechanism for acantholysis after pemphigus IgG binds to the cell surface is as yet unknown, although involvement of proteinases such as plasminogen activator (PA) has been suggested. We previously reported that pemphigus IgG, but not normal nor bullous pemphigoid IgGs, caused a transient increase in intracellular calcium ([Ca++]i) and inositol 1,4,5-trisphosphate (IP3) concentration in cultured DJM-1 cells (a squamous cell carcinoma line). To clarify whether phospholipase C is involved in this process after the antibody binds to the cell surface, we examined the effects of a specific phospholipase C inhibitor (U73122) on the pemphigus IgG-induced increase in [Ca++]i, IP3, PA secretion, and cell-cell detachment in DJM-1 cells. [Ca+2]i and IP3 contents were determined with or without 30-min pre-incubation with U73122 or an inactive analogue (U73343) with fura-2 acetoxymethylester and a specific IP3 binding protein, respectively. PA activity in the culture medium was measured after various incubation periods with pemphigus IgG by two-step amidolytic assay. The detachment of cell-cell contacts was examined by detecting the retraction of keratin filament bundle from cell-cell contact points to the perinuclear region by immunofluorescence microscopy using anti-keratin antibody. Pemphigus IgG immediately increased [Ca++]i and IP3 content. PA activity in the culture medium has also been increased at 24 h after pemphigus IgG was added in association with cell-cell detachment. However, pre-incubation with U73122 (1-10 microM), but not with U73343 (10 microM), dramatically reduced the pemphigus IgG-induced increases in [Ca++]i, IP3, and PA activity and inhibited the pemphigus IgG-induced cell-cell detachment. Both U73122 and U73343 caused no effects on cell viability and IgG binding to the cell surface. These results suggest that phospholipase C plays an important role in transmembrane signaling leading to cell-cell detachment exerted by pemphigus IgG binding to the cell surface.

Pemphigus IgG induces expression of urokinase plasminogen activator receptor on the cell surface of cultured keratinocytes.

We previously found that the binding of pemphigus IgG to desmogleins caused marked activation of phospholipase C, a transient increase in inositol 1,4,5-trisphosphate production, and a concomitant increase in the intracellular calcium concentration in DJM-1 cells, a squamous cell carcinoma line. The binding of pemphigus IgG to cell membranes increased the activity of urokinase plasminogen activator in culture medium and induced subsequent cell-cell detachment in DJM-1 cells. Because urokinase plasminogen activator activates the conversion of plasminogen to plasmin by binding to urokinase plasminogen activator receptor evading inhibitors in serum, it is likely that plasmin is generated only in microenvironments adjacent to urokinase plasminogen activator receptor on the cell surface. It is not known whether pemphigus IgG causes acantholysis by inducing urokinase plasminogen activator receptor expression on the cell surface and secreting urokinase plasminogen activator in inhibitor-rich environments. We examined the effects of pemphigus IgG on urokinase plasminogen activator receptor expression in DJM-1 cells and normal keratinocytes by immunoblot analysis and immunofluorescence microscopy using antibodies to urokinase plasminogen activator receptor. IgG were obtained from serum samples from eight patients with bullous pemphigoid, five patients with pemphigus vulgaris, seven patients with pemphigus foliaceus, and eight normal subjects. Pemphigus vulgaris and pemphigus foliaceus IgG significantly increased the urokinase plasminogen activator receptor expression on the surface of DJM-1 cells and normal keratinocytes after 3- and 7-d incubation compared with normal IgG. These results suggest that enhanced urokinase plasminogen activator activity and urokinase plasminogen activator receptor expression activates plasmin in the limited cell surface of pemphigus IgG-bound keratinocytes and may contribute to the pathogenesis of differential acantholysis in pemphigus vulgaris and pemphigus foliaceus.

Pemphigus IgG, but not bullous pemphigoid IgG, causes a transient increase in intracellular calcium and inositol 1,4,5-triphosphate in DJM-1 cells, a squamous cell carcinoma line.

It is still unclear what kinds of mechanisms are involved in blister formation after antibodies bind to the antigens in pemphigus and bullous pemphigoid. The effects of IgGs from pemphigus vulgaris, pemphigus foliaceus, and bullous pemphigoid sera on intracellular calcium concentration ([Ca++]i) and inositol 1,4,5-trisphosphate were examined in a human squamous cell carcinoma cell line (DJM-1 cells) and in cultured human keratinocytes to clarify whether signal transduction via calcium is involved. IgGs were purified with protein A affinity column from the sera of five pemphigus vulgaris patients, three pemphigus foliaceus patients, eight bullous pemphigoid patients, and 14 normal volunteers. Keratinocytes were cultured in Eagle's minimum essential medium containing 1.8 mM Ca++ and loaded with fura-2/AM, followed by addition of the IgGs. Subsequently, [Ca++]i was determined by measuring the fluorescence ratio (F340/F360) with videomicroscopy. Pemphigus IgGs (seven of eight cases) induced a rapid and transient increase in [Ca++]i in both the cells, whereas a [Ca++]i increase was caused by very few IgGs from bullous pemphigoid (one of eight cases) and normal sera (two of 14 cases). The pemphigus IgG-induced transient [Ca++]i increase was not affected by chelating extracellular Ca++ with ethyleneglycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetracetic acid. In addition, monoclonal antibodies acid. In addition, monoclonal antibodies against 180-kD and 230-kD antigens did not exert this change. Pemphigus IgGs that caused a [Ca++]i increase induced rapid and transient production of inositol 1,4,5-trisphosphate, peaking at 20 seconds. These findings suggest that IgG from pemphigus induces Ca++ mobilization by inositol 1,4,5-trisphosphate from internal stores, and that mechanisms of antibody-transmitted signaling in pemphigus may differ from those in bullous pemphigoid.

Activin A induces terminal differentiation of cultured human keratinocytes.

Activin A, a member of the TGFbeta-superfamily, is well known to play important roles in the growth and differentiation of various target cells. We have previously demonstrated that activin A is produced at an early stage of cultivation at both the protein and the mRNA levels in cultured human keratinocytes. In this study, the effects of activin A on differentiation and proliferation of human keratinocytes were examined. Activin A (> or =1 nM) induced cornified envelope formation and the synthesis of loricrin, keratin 1, involucrin, and transglutaminase 1. In addition, transglutaminase activity and mRNA level of transglutaminase 1 were increased by activin A. [3H]Thymidine incorporation and cell number were reduced by activin A (> or =1 nM) compared with control, suggesting an inhibitory effect of activin A on cell proliferation. On the basis of these findings, it is likely that activin A contributes to differentiation and suppression of proliferation in human keratinocytes.

Expression of activin A in human keratinocytes at early stages of cultivation.

Activins are members of the TGF-beta superfamily and are classified into 3 types: activin A, which consists of a homodimer of betaA, activin B, which consists of a homodimer of betaB, and activin AB, which consists of a heterodimer of betaAbetaB. We studied the expression of activin mRNAs by RT-PCR in normal human epidermis, cultured keratinocytes, and DJM-1 cells (a squamous cell carcinoma line). We could detect only activin A mRNA (betaA) in normal human epidermis. In cultured keratinocytes and DJM-1 cells, activin betaA mRNA was observed at 4 h but not at 96 h after plating. Activin A activity was detected in the conditioned medium of DJM-1 cells within 48 h. In addition, although follistatin mRNA was not observed in human epidermis in situ, it was transiently expressed in cultured cells at 4 h after plating. These findings suggest that the expression of these molecules in keratinocytes is associated with cell proliferation. In an in vitro tissue injury model, activin A was observed at the wound edge, where cell migration and proliferation may be activated. In DJM-1 cells cultured for 92 h, betaA mRNA was observed 4 h after injury treatment. These findings suggest that activin A acts as a potent inducer of proliferation in vitro, at least in keratinocytes.