Immunolocalization of human gelatinase (type IV collagenase, MMP-9) and tissue inhibitor of metalloproteinase 1 in Hailey-Hailey and Darier's diseases

BACKGROUND

The formation of lacunae and acantholysis as well as dyskeratosis are characteristic features of Hailey-Hailey disease (HHD) and Darier's disease (DD). Matrix metalloproteinases (MMPs) and their inhibitors like tissue inhibitors of metalloproteinases (TIMPs) have been thought to play major roles in the tissue metabolism.

OBJECTIVE

The aim of this study was to investigate the role of MMP-9 and TIMP-1 in HHD and DD.

METHODS

We examined localizations of these two molecules by immunostaining using specific monoclonal antibodies.

RESULTS

MMP-9 was positively stained in dyskeratotic or detaching cells around lacunae in HHD and DD. TIMP-1 showed a positive staining pattern throughout the epidermis.

CONCLUSION

MMP-9 might be involved in the pathophysiological process of HHD and DD in the presence of TIMP-1.

Heterogeneous reactivity with LH7.2 and the first prenatal diagnosis of generalized recessive dystrophic epidermolysis bullosa among Japanese patients

BACKGROUND

The heterogeneity of abnormal patterns of expression of type VII collagen in the skin of Japanese patients with generalized recessive dystrophic epidermolysis bullosa (g-RDEB) remains unclear, and the prenatal diagnosis of this condition has not yet been performed in Asia.

OBJECTIVE

The present study was performed to clarify patterns of abnormal expression of type VII collagen among Japanese patients with g-RDEB, and to evaluate the first application of prenatal diagnosis for this condition in an Asian country.

METHODS AND RESULTS

Only 2 of 8 Japanese patients with g-RDEB evaluated demonstrated a complete absence of type VII collagen at the skin basement membrane zone when tested with an LH7.2 monoclonal antibody. The other 6 patients revealed present, although diminished, LH7.2 reactivity. The mother of 1 patient who lacked reactivity to the LH7.2 monoclonal antibody sought prenatal diagnosis. Electron microscopy of fetal skin specimens obtained at 19 weeks' gestation showed mature anchoring fibrils with no separation of the dermis and epidermis. Indirect immunofluorescence revealed normal expression of type VII collagen. The fetus was diagnosed as being unaffected, and a normal female infant was delivered at 38 weeks' gestation.

CONCLUSION

Our findings indicate a lower incidence of the negative expression of LH7.2 epitope in the type VII collagen among Japanese rather than non-Japanese patients with g-RDEB. However, LH7.2 still serves as a reliable diagnostic probe under certain conditions such as the diagnosis and prenatal diagnosis of g-RDEB as in the present case.

A case of herpetiform pemphigus associated with autoimmune hemolytic anemia: detection of autoantibodies against multiple epidermal antigens

We report a case who was clinically and histopathologically diagnosed as herpetiform pemphigus (HP) and associated with autoimmune hemolytic anemia (AIHA). However, immunofluorescence studies demonstrated concurrent anti-cell-surface and anti-basement-membrane-zone antibodies in the patient's serum. Immunochemical studies showed that the patient's serum reacted with both the pemphigus foliaceus antigen and the two bullous pemphigoid antigens. Subsequently, the patient developed AIHA. Both anemia and skin lesions were successfully treated with oral prednisolone. We believe that this is the first case with HP in association with AIHA. The presence of autoantibodies against multiple antigens suggests an abnormal immunologic tolerance in the antibody production system in this patient.

Inhibition of purified (Na+,K+)-ATPase activity from porcine cerebral cortex by NO generating drugs

We tested the effects of several nitric oxide (NO) generating compounds on the activity of sodium-potassium adenosine 5'-triphosphatase [(Na+,K+)-ATPase] purified from porcine cerebral cortex. Sodium nitroprusside (SNP), S-nitroso-N-acetylpenicillamine (SNAP), 3-morpholinosydnonimine (SIN-1) and (d1)-(E)-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexeneamide (NOR 3) inhibited the (Na+,K+)-ATPase activity dose dependently. Superoxide dismutase, a NO scavenger, and sulfhydryl (SH) compounds, reduced-form glutathione (rGSH) and dithiothreitol (DTT), prevented the inhibitory action of SNAP, SIN-1 and NOR 3 but not of SNP, when applied simultaneously with NO generating compounds, and this enzyme inhibition could be reactivated by the incubation with these SH compounds but not with SOD. The inhibitory action by SNP was magnified by simultaneous application of DTT. These results suggest that NO generating compounds, SNAP, SIN-1 and NOR 3 but not SNP, may release NO or NO-derived products and may inhibit (Na+,K+)-ATPase activity by interacting with a SH group at the active site of the enzyme.

Dystrophic form of inherited epidermolysis bullosa in a dog (Akita Inu)

We report a dog with dystrophic epidermolysis bullosa. This 4-year-old female Akita Inu, a species of Canis familiaris var. japonicus Temminck, had a 3-year-history of ulcers and scars over the pressure areas on the limbs, and dystrophic nails, since the age of 1 year, which corresponds to early adulthood in humans. Electron microscopy of a blister revealed separation beneath the lamina densa, and a reduction in the number of anchoring fibrils. The NC-1 domain of type VII collagen was positively stained with monoclonal antibody LH7.2 at the basement membrane zone. These findings indicate that humans and dogs have a similar response to antibody LH7.2, which may aid the development of an animal model for this disease.

T cell response to Borrelia garinii, Borrelia afzelii, and Borrelia japonica in various congenic mouse strains

The infectivity and T cell response to Borrelia garinii SIKA2, Borrelia afzelii BFOX, and Borrelia japonica 0612, the organisms that cause Lyme disease in Japan, were examined in various inbred and congenic strains of mice. Infectivity differed among the species: B. garinii SIKA2 and B. afzelii BFOX were each able to infect 90% to 100% of C3H/He mice; B. japonica 0612 was able to infect only 20% of C3H/He mice. The pattern of infectivity to various inbred and congenic strains of mice may influence the pathogenicity of the organism and the clinical signs of Lyme disease. Cross-reactivity between Borrelia antigens was observed, but there was no cross-reactivity between Borrelia antigens and Leptospira antigens. We evaluated the genetic control of the delayed-type hypersensitivity (DTH) reaction in the form of footpad swelling produced by Borrelia antigens using viable or sonicated bacteria as sensitization. Differences in strains of mice infected by viable antigen were observed. However, all strains of mice showed a strong DTH reaction using sonicated antigens without genetic background. A DTH reaction in the form of footpad swelling did not appear to be associated with genetic background. The footpad reaction was mediated by CD4+8- and Ia- T cells, as revealed by in vitro monoclonal antibody treatment. However, CD8+ T cells did not suppress footpad swelling. These results indicate that many antigenic epitopes of the Borrelia spirochete can stimulate the DTH reaction.

Endotoxin induces severe inflammatory reactions with necrosis at sites primed with delayed-type hypersensitivity reactions in guinea pigs

Guinea pigs immunized with Freund's complete adjuvant received challenge injection of the purified protein derivative of Mycobacterium tuberculosis in the flanks and the corneas to prepare delayed-type hypersensitivity (DTH) reactions. The animals were injected subcutaneously with lipopolysaccharide (LPS) or a synthetic lipid A (LA-15-PP). At the skin site primed with DTH reaction, increased swelling and hemorrhagic reaction followed by a definite necrotic reaction occurred. Severe corneal reactions were also observed in the animals. These findings indicate that bacterial endotoxin modulates DTH reactions and induces severe inflammatory reactions.

Comparative study of autoantigens for various bullous skin diseases by immunoblotting using different dermo-epidermal separation techniques

We investigated the reactivity of pemphigus vulgaris (PV), pemphigus vegetans, pemphigus foliaceus (Pf), Brazilian Pf, bullous pemphigoid (BP), and epidermolysis bullosa acquisita (EBA) sera with an immunoblot analysis using human epidermal and dermal extracts as a source of antigen. To obtain epidermal and dermal extracts three different dermo-epidermal separation methods were used: namely, ethylenediaminetetraacetic acid (EDTA) separation, heat separation, and dispase separation. All the 15 PV and the seven pemphigus vegetans sera demonstrated a 130-kDa PV antigen in epidermal extracts obtained by all the three methods. Furthermore, three PV sera also showed a 160-kDa Pf antigen, desmoglein. Ten of 14 Pf sera and six of 15 Brazilian Pf sera reacted with desmoglein in the same pattern in all the three epidermal extracts. Fifteen of the 22 BP sera showed reactivity with 230-kDa BP antigen in the same pattern in all the three epidermal extracts, whereas 14 BP sera detected the 180-kDa BP antigen in extracts of EDTA- and heat-separated epidermis but not in dispase-separated epidermal extract. Dermal extracts were obtained by EDTA- and heat-separated dermis, and all six EBA sera labelled a 290-kDa EBA antigen in both samples. These results suggest that heat-separated skin is as useful as EDTA-separated skin for detecting various autoantigens, but heat separation is preferable because the preparation time is shorter.

[Bullous pemphigoid simulation subacute simple prurigo]

Bullous pemphigoid (BP) is a bullous autoimmune disease of the elderly; it is characterized by tense bullae on both erythematous and otherwise apparently normal skin. Several clinical variants of BP have been described, and we now add our observations of two BP cases mimicking subacute prurigo. Both patients had suffered from intensely pruritic excoriated papules for several months before presentation. Blisters had never developed and did not occur during follow up. Histology showed changes of chronic dermatitis. In the serum of both patients, indirect immunofluorescence on NaCl-separated human skin revealed the presence of circulating antibodies binding to the roof of the artificial blisters. Perilesional skin biopsies showed linear IgG or C3-deposits in the basement membrane zone. Immunoblotting of epidermal and dermal extracts demonstrated the binding of the antibodies to an epidermal 230-kD protein, which is the known major bullous pemphigoid antigen. These cases are described as a basis for discussion of the clinical spectrum of bullous pemphigoid.

Effects of clonidine premedication on the pressor response to alpha-adrenergic agonists

It has been suggested that postjunctional alpha 1-adrenoceptor mediated vasoconstriction is enhanced by clonidine. We have examined in humans if the pressor responses to noradrenaline and phenylephrine are enhanced by clonidine premedication. Seventy-seven patients were allocated randomly to either clonidine (n = 38) or control (n = 39) groups. Patients in the clonidine group received approximately 5 micrograms kg-1 with famotidine 20 mg, while the control group received famotidine 20 mg alone orally, 90 min before induction of general anaesthesia with thiamylal. In all patients the lungs were ventilated mechanically via tracheal tubes and anaesthesia maintained with 1% end-tidal enflurane and 67% nitrous oxide in oxygen. When a stable haemodynamic state was obtained, either noradrenaline 0.5 microgram kg-1 (n = 40) or phenylephrine 2 micrograms kg-1 (n = 37) was administered randomly i.v. as a bolus, while arterial pressure and heart rate were measured noninvasively at 1-min intervals for 10 min. Although noradrenaline caused significantly greater increases in mean arterial pressure (MAP) in the clonidine group (from 2 to 4 min after i.v. injection) compared with the control group, there were no significant differences in the mean maximal increment in MAP or area under the MAP curve between the two groups. However, i.v. phenylephrine produced a significantly greater increase in MAP from 2 to 7 min (P < 0.05), and greater mean maximal increase in MAP from the baseline value (21 (9) vs 14 (7) mm Hg; P < 0.05) in the clonidine than in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Demonstration of antibodies to bovine desmocollin isoforms in certain pemphigus sera

We have shown previously that IgG antibodies in certain pemphigus sera, particularly endemic Brazilian pemphigus foliaceus (BPF) sera, react with bovine desmocollins (Dsc), which are transmembranous glycoproteins of desmosome junctions. Desmocollins occur as three different isoforms (Dsc 1, 2 and 3), all of which are represented in the epidermis. In this study, we examined sera of various pemphigus types by immunoblotting purified bovine desmosomes and bovine Dsc 1, 2 and 3 fusion proteins, expressed in pGEX expression vectors. Six of 15 (40.0%) BPF sera, two of 18 (11.1%) non-endemic pemphigus foliaceus sera, eight of 39 (20.5%) pemphigus vulgaris (PV) sera, and two of 11 (18.2%) normal sera, showed reactivity with Dsc from desmosomes. Experiments with fusion proteins showed that no Dsc isoform was specifically recognized by sera of any individual pemphigus type. Our results indicate that the pathogenesis of pemphigus might be more complex than previously believed.

A case of deoxycorticosterone-producing adrenal adenoma

A 29-year-old woman with deoxycorticosterone (DOC)-producing adrenocortical adenoma had hypertension and hypokalemia but without Cushingoid features. Plasma renin activity and the aldosterone concentration were low, while the DOC concentration was high (6.10-10.3 ng/ml; normal range 0.03-0.33). Plasma cortisol, androgens, and estrogens as well as urinary 17-OHCS and 17-KS were within normal limits. Furosemide administration and two hours upright posture resulted in a 3-fold increase in plasma DOC, but the administration of ACTH, dexamethasone, or angiotensin III had no effect on plasma DOC. Following resection of a right adrenal tumor weighing 70 g, the hypertension and hypokalemia disappeared. DOC content in the tumor was high. On light microscopic examination, the tumor was encapsulated, composed of cells with clear cytoplasm and large nuclei and there were extensive areas of fibrosis and infiltration of lymphocytes. According to Weiss's criteria, the tumor was considered to be an adrenocortical adenoma. Immunohistochemically, P450scc, 3 beta HSD, P450C21 and P45011 beta were positive with heterogeneity of intra-tumoral expression. No immunoreactivity for P45017 alpha in this adenoma was detected. This is different from a previous report in which a relatively small number of cells in DOC-secreting adrenocortical carcinoma were positive for P45017 alpha.

Untreated Graves' disease patients without clinical ophthalmopathy demonstrate a high frequency of extraocular muscle (EOM) enlargement by magnetic resonance

12 of 17, a significant frequency (71%), of untreated Graves' disease patients with no clinical ophthalmopathy showed extraocular muscle (EOM) enlargement by Magnetic Resonance Imaging (MRI). Enlargement was bilateral in 41% and unilateral in 29% in these patients. Apparent enlargements of EOM were also detected, by MRI, in all of 11 Graves' disease patients with clinical ophthalmopathy, bilateral in 73% and unilateral in 27% of patients in this group. Both group showed the inferior rectus muscle as the most frequently involved (56% and 77% respectively). In 16 patients without autoimmune thyroid disorders or ophthalmopathy who served as normal controls, only 2 of these patients (12%) demonstrated mild EOM enlargement. The severity and patterns of EOM enlargement revealed no correlation with abnormalities in serum thyroid function tests or serum thyroidal autoantibodies. In conclusion, a high frequency of Graves' disease patients without clinical eye signs or symptoms harbor EOM abnormalities, as demonstrated by MRI. This suggests that present clinical examination methods are insufficient to diagnose varying degrees of ophthalmopathy in patients with autoimmune thyroid disorders who do not initially present with clinical ophthalmopathy.

Multiple abdominal telangiectases and lymphangiectases. A limited form of Osler-Weber-Rendu disease?

We describe a 23-year-old man with protein-losing enteropathy, iron deficiency anemia, and recurrent gastrointestinal bleeding. The patient eventually developed disseminated intravascular coagulation, portal vein thrombosis, and extensive small bowel infarction. The autopsy showed multiple telangiectases in the intestines, mesentery, liver, gallbladder, renal pelves, and diaphragm. In addition, lymphangiectases were found in the retroperitoneal space, intestines, and liver. These lesions appeared to have been the cause of the gastrointestinal bleeding and the protein-losing enteropathy. The case most likely represents Osler-Weber-Rendu disease without the usual manifestations in the skin and oral-nasal cavities.

The addition of epinephrine enhances postoperative analgesia by intrathecal morphine

To investigate whether the addition of epinephrine would enhance postoperative pain relief by intrathecal morphine, we studied 36 patients scheduled to have spinal anesthesia for gynecologic surgery. Patients were randomly allocated to one of three groups: the first received epinephrine 0.12 mg, morphine 0.2 mg, and hyperbaric tetracaine 12 mg intrathecally (EMT group, n = 11); the second received morphine 0.2 mg and hyperbaric tetracaine 12 mg intrathecally (MT group, n = 13); and the third received epinephrine 0.12 mg and hyperbaric tetracaine 12 mg intrathecally (ET group, n = 12). The time to the first request for supplemental analgesics was longest (2182 +/- 251 min, mean +/- SEM) and the injection number of supplemental analgesics was least in the EMT group (P < 0.05). The percentage of patients who received supplemental analgesics in the EMT group (45.5%) was less than the other two groups (P < 0.05). Six patients in the EMT group and one in the MT group needed no additional analgesics during 48 h (P < 0.05 versus the MT and ET groups). The visual analog scale (VAS) pain score was larger in the ET group than the EMT group (P < 0.05), but was similar in the EMT and MT groups. There were no differences among groups in the incidence of nausea and pruritus. Our data show that the addition of epinephrine enhances postoperative analgesia by intrathecal morphine without increasing the incidence of adverse effects as compared with intrathecal morphine alone.

Phosphorylation of proteasome substrate by a protein kinase associated with the 26 S proteasome is linked to the ATP-dependent proteolysis of the 26 S proteasome

A protein kinase phosphorylating the 45-kDa proteasome subunit was co-purified with the 26 S proteasome from the porcine heart. This kinase appears to be associated with the 26 S proteasome, since the kinase activity was co-eluted with the 26 S proteasome on Superose 6 FPLC and immunoprecipitated with anti-20 S proteasome antibody. This kinase also phosphorylated the casein. Furthermore, the phosphorylated casein was more efficiently hydrolyzed by the 26 S proteasome than the dephosphorylated casein without ATP. Inhibition patterns of kinase inhibitors against the 45 kDa subunit and casein were well in accord with the inhibition pattern against the ATP-dependent proteolysis of the 26 S proteasome, suggesting that the phosphorylation of casein by a protein kinase associated with the 26 S proteasome is linked to the ATP-dependent proteolysis of the 26 S proteasome.

Anatomical distribution and postnatal changes in endogenous free D-aspartate and D-serine in rat brain and periphery

We have investigated the anatomical distribution and postnatal development of D-aspartate and D-serine in the rat brain and periphery using HPLC techniques. D-Serine was confined predominantly to the brain throughout postnatal life. At birth, a substantial quantity of D-serine was observed throughout the brain areas. The cerebral D-serine content increased from birth to postnatal week (PW) 3 and remained constant thereafter, whereas the cerebellar D-serine content peaked at PW1. In contrast, the transient emergence of D-aspartate was found in almost all brain and peripheral organs. A substantial quantity of D-aspartate was also seen in all brain areas at birth, whereas the D-aspartate content in the cerebrum and cerebellum decreased dramatically by PW1 and 7 respectively. Further, the D-aspartate content and the ratio of D-aspartate to total aspartate were highest in the adrenal at PW3 (608 +/- 70 nmol/g, 45.9%) and in the testis at PW14 (221 +/- 7 nmol/g, 57.8%) respectively. Because D-serine potentiates N-methyl-D-aspartate receptor-mediated transmission through the strychnine-insensitive glycine site and because D-serine exhibits an N-methyl-D-aspartate receptor-related distribution and development, D-serine may be a tenable candidate for an intrinsic ligand for the glycine site. In contrast, because the periods of maximal emergence of D-aspartate in the brain and periphery occur during critical periods of morphological and functional maturation of organs, D-aspartate could participate in the regulation of these developmental processes of organs.

Restricted usage of T cell receptor V alpha-V beta genes in infiltrating cells in the hearts of patients with acute myocarditis and dilated cardiomyopathy

Prolonged myocardial cell damage initiated by acute myocarditis is thought to be one of the most important etiology of dilated cardiomyopathy. To investigate the immunological mechanisms involved in the pathogenesis of dilated cardiomyopathy, we analyzed the phenotypes of infiltrating cells and examined the expression of perforin in infiltrating cells in the hearts of patients with dilated cardiomyopathy as well as acute myocarditis. We also examined the expression of HLA and intercellular adhesion molecule-1 (ICAM-1) in myocardial tissue of these patients. Furthermore, to evaluate the antigen specificity of infiltrating T cells and persistence of viral genomes in the myocardial tissue, we analyzed the expression of T cell receptor (TCR) V alpha and V beta genes as well as enterovirus genomes by PCR. We found infiltration of perforin-expressing killer cells and enhanced expression of HLA class I and ICAM-1 in the myocardial tissue. We also found that the repertoires of TCR V alpha as well as V beta gene transcripts were restricted, indicating that a specific antigen in the hearts was targeted. Because no enterovirus genomes were detected in all patients, it is strongly suggested that a cell-mediated autoimmune mechanism triggered by virus infection may play a critical role in the pathogenesis of dilated cardiomyopathy. However, we could not exclude the possibility that viruses other than enteroviruses could be pathogenic in these patients.

Conformational epitopes of pemphigus antigens (Dsg1 and Dsg3) are calcium dependent and glycosylation independent

The target molecule of pemphigus autoantibodies is a transmembrane desmosomal component, desmoglein 3 (Dsg3) in pemphigus vulgaris (PV) and Dsg1 in pemphigus foliaceus (PF). In this study, we examined the effects of calcium and glycosylation on the anti-genicity of the pemphigus antigens and on the generation of conformational epitopes. We used recombinant baculovirus proteins, PVIg and PFIg, which are considered to reflect accurately the native conformation of the extracellular domain of their respective proteins Dsg3 and Dsg1. These baculoproteins could immunoadsorb heterogeneous autoantibodies from the corresponding sera of PV and PF patients, completely blocking indirect immunofluorescence staining of normal human skin. Chelating calcium from the solution containing the baculoproteins using ethylenediaminetetraacetic acid (EDTA) or ethyleneglycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) abolished immunoadsorption by both PVIg and PFIg; however, immunoadsorption by the baculoproteins was restored after dialysis against 1 mM calcium. Nonglycosylated forms of both baculoproteins produced in the presence of tunicamycin retained their immunoadsorptive ability. Furthermore, immunoadsorption by the baculo-proteins was prevented irreversibly by treatment with low pH, high pH, and boiling, but not with the non-ionic detergent Nonidet P-40. These findings indicate that formation of the conformational epitopes on the pemphigus antigens is dependent on calcium but independent of glycosylation, and provide direct evidence that calcium plays an important role in determining the antigenic properties of the pemphigus antigens.

Nonisotopic receptor assay for benzodiazepine drugs using time-resolved fluorometry

A nonisotopic receptor assay for benzodiazepine drugs using a time-resolved fluorometric technique is described. A novel europium chelate-labeled benzodiazepine (Eu-1012-S) was prepared as a probe ligand for the binding assay based on the competitive inhibition of Eu-1012-S binding by benzodiazepine drugs to their receptors. In this system, the degree of the inhibition was proportional to the affinity of drugs for the receptor. Background fluorescence did not interfere with the measurement, due to the long-lifetime fluorescence of Eu-1012-S. The proposed nonisotopic assay may provide an alternative to radioreceptor assays of benzodiazepines in biological systems and could also be used to screen new benzodiazepine-like compounds from nature.

Pemphigus vulgaris and pemphigus foliaceus sera show an inversely graded binding pattern to extracellular regions of desmosomes in different layers of human epidermis

We analyzed the location of binding sites for pemphigus vulgaris (PV) antigen and pemphigus foliaceus (PF) antigen in the human epidermis using serum samples obtained from three patients with PV and three patients with PF. Confocal laser scanning microscopy, immunofluorescent examination of ultrathin cryosections, and immunoperoxidase electron microscopy demonstrated discontinuous dots along the epidermal cell surfaces. Immunogold electron microscopy of ultrathin cryosections showed specific binding of PV and PF autoantibodies only to desmosomes. Post-embedding immunogold electron microscopy using cryofixation and cryosubstitution enabled the whole depth of the epidermis to be examined and the binding of PV and PF autoantibodies to be quantitated by counting gold particles. Both PV and PF autoantibodies bound to all desmosomes in the epidermis, but not to the surface of the non-desmosomal keratinocytes. The majority of auto-antibody binding occurred in the extracellular domain (PV, 62%; PF, 69%). The statistical analysis of two-way analysis of variance regarding the number of gold particles labeling a single desmosome confirmed a significant interaction between subtypes of pemphigus (PV and PF) and the different epidermal cell layers (p < 0.044). The results indicate that the number of gold particles bound to individual desmosomes with PV sera was significantly higher in the lower epidermis than in the upper epidermis, and that of PF sera showed reciprocal pattern. This inversely graded binding pattern suggests heterogeneity of the composition of the desmosomes, which may explain the differences in level of acantholysis between PV and PF.

Epidermal melanocytes in normal and tyrosinase-negative oculocutaneous albinism fetuses

In tyrosinase-negative (type IA) oculocutaneous albinism (tyr(-) OCA) fetuses the development of melanocytes has not been fully elucidated. We analysed the distribution of melanocytes in skin samples from a fetus with tyr(-) OCA and from four normal fetuses. Skin samples obtained from 12 different body sites of each fetus were examined by transmission electron microscopy, an electron microscopic DOPA reaction test and immunohistochemistry. No S100 protein-positive cells were detected in any sample. There were fewer HMB-45-positive melanocytes in the skin of the tyr(-) OCA fetus than in the skin of normal fetuses from all body sites sampled. The greatest number of HMB-45-positive melanocytes was present in samples from the scalp of the normal fetuses and in those from the lower limbs of the tyr(-) OCA fetus. Very few melanocytes were detected immunohistochemically in samples from the soles and palms, though their presence was confirmed by transmission electron microscopy. The electron microscopic DOPA reaction test enhanced the melanization of melanocytes in samples from the normal fetuses but not in those from the tyr(-) OCA fetus. Postembedding immunogold electron microscopy using the HMB-45 antibody revealed that the HMB-45 antigen was localized mainly on stages I and II melanosomes. The presence of epidermal melanocytes in samples from all fetal body areas obtained at 17-21 weeks of gestation justifies the use of the electron microscopic DOPA reaction test in the prenatal diagnosis of tyr(-) OCA.