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Biomedical subjects

L S Chan

Publications and source records attributed to L S Chan.

At least 73 records · Page 4Linked to original sources
PubMed1998

Relative bradycardia in patients with traumatic hypotension.

BACKGROUND: Tachycardia is considered a physiologic response to traumatic hypotension. The inability of the heart to respond to shock with tachycardia has been described as paradoxical bradycardia or relative bradycardia. The incidence and clinical significance of this condition in major trauma is not known. The objective of this study was to examine the incidence and prognostic significance of tachycardia and relative bradycardia in patients with traumatic hypotension. Relative bradycardia is defined as a systolic pressure < or = 90 mm Hg and a pulse rate < or = 90 beats per minute. METHODS: This is a retrospective study conducted at a large Level I academic trauma center during a 4-year period. Seventeen demographic and injury severity factors were analyzed for their possible role in tachycardic or bradycardic response in hypotensive patients. Incidence and mortality were derived for each subpopulation. Bivariate analysis of the association of incidence and mortality with each risk factor was performed. Factors with p values < 0.2 were included in stepwise logistic regression analyses that identified significant risk factors and derived adjusted relative mortality risks between tachycardic and bradycardic hypotensive patients. RESULTS: Excluding transfers and patients dead on arrival, 10,833 major trauma patients were seen during the study period. Seven hundred fifty patients (6.9%) had systolic blood pressure < or = 90 mm Hg; 533 patients had tachycardia (overall incidence of 4.9%, or 71.1% of hypotensive patients), and 217 patients had bradycardia (overall incidence of 2.0%, or 28.9% of hypotensive patients). The overall crude mortality was 29.2% among tachycardia patients and 21.7% among bradycardia patients (crude relative risk = 1.34; 95% confidence interval = 1.00-1.81; p = 0.047). The adjusted relative mortality risk between the two groups was 1.23 (95% confidence interval = 0.84-1.73; p = 0.284). Multivariate analysis showed that patients with relative bradycardia in the subgroups with Injury Severity Scores > or = 16, chest Abbreviated Injury Scale scores > or = 3, or abdominal Abbreviated Injury Scale scores > or = 3 had significantly better survival than patients with similar injuries presenting with tachycardia. CONCLUSION: Relative bradycardia in hypotensive trauma patients is a common hemodynamic finding. Mortality among tachycardic patients was more predictable than among bradycardic patients using commonly used demographic and injury indicators. The presence of relative bradycardia in some subgroups of patients with severe injuries seems to be associated with better prognosis than the presence of tachycardia.

Adult↗
PubMed1998

The high morbidity of colostomy closure after trauma: further support for the primary repair of colon injuries.

BACKGROUND: We examined the recent experience of a large urban trauma center to identify overall morbidity and factors predictive of outcome in patients undergoing colostomy closure after trauma. METHODS: We did a retrospective analysis of 40 patients who underwent colostomy closure after trauma at our institution between January 1992 and August 1996. RESULTS: The mechanism of injury was a gunshot wound in 30 patients (75%), a motor vehicle accident in 6 (15%), a stab wound in 3 (7.5%), and a rectal foreign body in 1 (2.5%). Loop colostomies were performed in 28 patients (70%) and end colostomies were performed in 12 patients (30%). Mean time until colostomy closure was 8 months (range, 0.5 to 28 months). Five patients underwent same admission colostomy closure (SACC). Contrast enemas were performed in 36 patients and found to be abnormal in 2 (6%) patients who were found during planning for SACC to have leaks from rectal trauma at 12 and 19 days after injury. Sixteen complications occurred in 12 patients (30%). Intraoperative complications occurred in two patients (5%) who sustained small and large bowel enterotomies. There were 4 major complications (1 fecal fistula, 1 anastomotic stricture, and 2 small bowel obstructions) in 3 patients (7.5%) and 10 minor complications (25%), 7 prolonged ileus and 3 superficial wound infections. Morbidity was significantly higher for patients whose initial injury involved the colon (11 of 20; 55%) as compared with those whose injury involved the rectum (2 of 16; 12.5%). The demographic, injury, and operative characteristics in the 12 patients with complications and the 28 patients without complications were compared to identify predictors of morbidity. The presence of a colon injury (RR = 7.70; p = 0.009) was a statistically significant predictor of morbidity after colostomy closure. The presence of an initial rectal injury, in contrast, was a predictor of low morbidity after closure (RR = 0.22; p = 0.024). No statistically significant differences were found with respect to age, gender, mode of injury, colostomy type, type of repair, need for laparotomy, or right- versus left-sided colostomy. Clinical trends were noted in five groups in whom the relative risk was greater than 2.0: age older than 30 versus less than 30 years (RR = 2.71; p = 0.079), end versus loop colostomy (RR = 2.33; p = 0.130), operative time greater than 2 versus less than 2 hours RR = 2.80; p = 0.141), estimated blood loss greater than 150 versus less than 150 cc (RR = 2.77; p = 0.079), and right- versus left-sided colostomy (RR = 2.00; p = 0.211). Patients with complications had significantly longer mean operative times (3.84 versus 2.46 hours; p = 0.02), higher mean blood loss (468 versus 142 cc; p = 0.006), and longer mean time until closure (11.3 versus 6.33 months; p = 0.02). CONCLUSIONS: Colostomy closure after trauma remains associated with significant morbidity. The patients in whom a colon injury was the indication for initial colostomy experienced high morbidity (55%) after subsequent closure. Patients who had a colostomy for rectal injury had a low morbidity after closure (6.25%). Intraoperative difficulties (longer operative times, higher blood loss) and long delays until colostomy closure increase complication rates. Timely closure may improve outcome after operation for bowel continuity restoration. Morbidity associated with colostomy closure should be considered additional evidence for performing primary repair of colonic injuries. Because the morbidity of colostomy closure after rectal injuries is low, proximal colostomy for extraperitoneal rectal injuries should remain the treatment of choice.

Adult↗
PubMed1998

The prevalence and effect of alcohol and drug abuse on cohort-matched critically injured patients.

A prospective study was undertaken at a Level I trauma center to evaluate the prevalence of substance use among victims of major trauma, along with the impact on clinical outcome. Five hundred sixteen patients had urine toxicology and blood alcohol screens performed and correlated with pattern and severity of injury, hospital course, and outcome. Three hundred seventy-one patients (71%) screened positive for alcohol or drugs, or both. Fifty-two per cent had positive alcohol screens, and 42 per cent had positive drug screens (cocaine and opiates represented 91% of positive drug screens). Univariate analysis revealed patterns of alcohol/drug use varied among subgroups according to demographics (less use among patients older than 55 years, females and Asians; more drug use in blacks; more alcohol use in Hispanics), mechanism of injury (non-use in blunt trauma patients and use of both in penetrating trauma patients) and body region injured (non-use in head-injured patients). Septic complications and mortality were more correlative with severity of injury, but not with use or non-use of alcohol or drugs. We conclude that alcohol and drug use remains a major comorbid factor in major trauma, and that injury prevention efforts should include a strong focus on counseling regarding these lifestyle choices.

Adolescent↗
PubMed1997

Human skin basement membrane in health and in autoimmune diseases.

Skin basement membrane zone (BMZ) is an ultrastructurally defined area situated between the outer layer of skin, the epidermis, and the inner layer of skin, the dermis. The major function of skin BMZ is to serve as an adherent connection between the epidermis and the dermis. Heritable skin diseases characterized by genetic mutations that result in defective BMZ protein production, such as junctional and dystrophic epidermolysis bullosa, manifest clinically as skin fragility and subepidermal blister formation inducible by minor trauma. Many distinct, yet interconnected BMZ components, have been identified and studied extensively. Some of these essential components, interestingly, were discovered because they were targeted by an autoimmune reaction. As a result of studying the autoimmune diseases, these BMZ components involved in autoimmune reaction, or autoantigens, were isolated by molecular biology techniques. The isolation of these autoantigens, in turn, facilitates our studies of the normal structures and functions of skin BMZ. The skin BMZ can be divided into four ultrastructurally distinct areas: the hemidesmosome/upper lamina lucida, the lower lamina lucida, the lamina densa, and the sub-lamina densa. Well-characterized BMZ components include the hemidesmosome/upper lamina lucida-located bullous pemphigoid antigens (BP230 and BP180), a 6b4 integrin, and plectin; the lower lamina lucida-located laminin-1, laminin-5 (previously named kalinin, epiligrin, nicein, BM600), laminin-6 (previously named k-laminin), p105, and entactin/nidogen; the lamina densa-located type IV collagen and perlecan; and the sub-lamina densa-located type VII collagen (epidermolysis bullosa acquisita antigen). Mucosal BMZ also contain identical components as skin BMZ. Autoantibodies targeting skin and/or mucosal BMZ components, like that of genetic mutation of BMZ components, result in a histopathologically defined subepidermal blistering disease, that is, a blister which occurs just below the epidermis/epithelium. Well-characterized autoimmune subepidermal blistering diseases include bullous pemphigoid (BP), linear IgA bullous dermatosis, cicatricial pemphigoid (with subsets of patients characterized by autoantibodies targeting either BP antigens or laminins), anti-p105 pemphigoid, and epidermolysis bullosa acquisita. Using a simple method of direct or indirect immunofluorescence testing on a skin section chemically separated at the middle portion of lamina lucida, in combination with immunoelectron microscopy and target antigen determination, accurate diagnoses for various autoimmune subepidermal blistering diseases can be obtained.

Antibody Formation↗
PubMed1997

Development of an ELISA for rapid detection of anti-type VII collagen autoantibodies in epidermolysis bullosa acquisita.

Epidermolysis bullosa acquisita (EBA) is an acquired blistering skin disease characterized by the presence of IgG autoantibodies to type VII collagen. EBA autoantibodies recognize four major immunodominant epitopes localized within the amino-terminal, noncollagenous (NC1) domain. In this study, we developed a rapid, quantitative enzyme-linked immunosorbent assay (ELISA) to detect autoantibody activity against the complete NC1 domain of type VII collagen with the use of an eukaryotic-expressed, recombinant human NC1 antigen. With the ELISA, we tested serum from patients with EBA (n = 24), bullous systemic lupus erythematosus (BSLE) (n = 3), bullous pemphigoid (n = 16), pemphigus (n = 11), and normal controls (n = 12). All EBA and BSLE serum, including four sera that were negative by indirect immunofluorescence, demonstrated reactivity with immobilized NC1 in the ELISA. In contrast, none of the sera from healthy control subjects or patients with unrelated blistering skin diseases reacted with NC1. The EBA sera also reacted with recombinant NC1 by immunoblot analysis but with less sensitivity. Thus, the newly developed ELISA using recombinant NC1 is a sensitive, specific assay and a useful tool for rapidly screening EBA and BSLE serum.

Autoantibodies↗
PubMed1997

Laminin-6 and laminin-5 are recognized by autoantibodies in a subset of cicatricial pemphigoid.

We characterized basement membrane zone (BMZ) autoantigens targeted by autoantibodies (AAb) from patients with cicatricial pemphigoid. Serum from a patient with severe oral cicatricial pemphigoid contained IgG anti-BMZ AAb. The AAb labeled a lower BMZ component on salt-split skin and localized to the lower lamina lucida/lamina densa by direct and indirect immunoelectron microscopy (IEM) but did not label blood vessels. The AAb did not react with EHS laminin-1 and type IV collagen, pepsinized human type IV collagen, recombinant entactin, or NC1 domain of type VII collagen by dot blotting and western blotting. We focused our studies on the laminin family, as laminin-5 was identified as an autoantigen in cicatricial pemphigoid. Culture-conditioned media from normal keratinocytes (containing laminin-6 and laminin-5) and JEB keratinocytes (containing laminin-6 but not laminin-5) were studied by western blotting. Under nonreducing conditions, the patient's AAb recognized a 600-kDa protein (laminin-6) intensely and a 400-kDa protein (laminin-5) weakly in normal keratinocyte medium even though abundant laminin-5 was present. InJEB keratinocyte medium, however, the 600-kDa protein (laminin-6) alone was recognized by the patient's AAb. The AAb also immunolabeled BMZ of JEB skin that lacked laminin-5. The AAb from this patient and two other patients with anti-laminin-5 cicatricial pemphigoid immunoprecipitated both laminin-6 and laminin-5. Taken together, the results of IEM, non-reducing western blotting, immunoprecipitation, and JEB skin BMZ immunolabeling indicate that laminin-6, as well as laminin-5, is identified by the AAb from a subset of cicatricial pemphigoid patients. We propose the name "anti-laminin cicatricial pemphigoid" for this subset.

Adult↗
PubMed1997

Significantly increased occurrence of HLA-DQB1*0301 allele in patients with ocular cicatricial pemphigoid.

To determine the immunogenetic characteristics of patients with immune-mediated subepithelial blistering diseases of mucous membranes, we performed HLA-typing for the class II MHC gene DQB1*0301 allele using a direct method. Genomic DNA extracted from Caucasian patients was amplified by polymerase chain reaction using primer pairs specific for the DQB loci followed by Southern blotting with a peroxidase-conjugated sequence-specific oligonucleotide probe. Seventy-six percent (16/21) of patients with ocular mucosal disease (with or without oral mucosal and skin diseases) carried the DQB1*0301 allele; by contrast, only 33% (14/42) of race-, age-, and geography-matched normal individuals carried the DQB1*0301 allele (p < 0.005). The relative risk for ocular disease if DQB1*0301 allele is present is 6.4, similar to the relative risk of 8 for patients with ocular but no oral disease (pure ocular cicatricial pemphigoid, p < 0.025). In patients with oral mucosal disease (with or without ocular mucosal and skin diseases), 68% (15/22) carried the DQB1*0301 allele (p < 0.025). When patients with ocular disease were excluded, however, the increased occurrence of the DQB1*0301 allele in patients with oral disease was not statistically significant (64%, 7/11, p < 0.25). In patients with subepidermal blistering skin disease but no oral or ocular disease, there was no increase in the occurrence of the DQB1*0301 allele (38%, 5/13, p > 0.5). The significantly increased occurrence of the DQB1*0301 allele in patients with ocular mucosal disease may point to a distinct immunogenetic factor that predisposes patients to develop an ocular scarring process.

Alleles↗
PubMed1997

Lesional psoriatic T cells contain the capacity to induce a T cell activation molecule CDw60 on normal keratinocytes.

In this report we demonstrate, that in psoriatic skin, basal and suprabasal keratinocytes express CDw60. The CDw60-specific monoclonal antibody, UM4D4, has recently been shown to recognize the 9-O-acetylated disialosyl group on ganglioside GD3. The CDw60 antigen on cultured keratinocytes also seems to be identical with the 9-O-acetylated disialosyl group, because the anti-UM4D4 binding was markedly reduced after neuraminidase treatment of keratinocytes. To examine whether factors from T cells in psoriatic lesions are responsible for the overexpression of CDw60 on keratinocytes, T cell lines obtained from lesional skin were initiated and cloned by limiting dilution. Factors released from 19 of 19 activated T cell clones up-regulated CDw60 expression on cultured normal keratinocytes. T-cell-secreted cytokines, including interleukin (IL)-2, IL-3, IL-4, IL-6, IL-13, transforming growth factor-beta, granulocyte/macrophage colony-stimulating factor, and interferon-gamma were tested for their capacity to modulate keratinocyte CDw60 expression. IL-4 and IL-13 strongly up-regulated the expression of CDw60; by contrast, interferon-gamma down-regulated keratinocyte CDw60 expression. Interestingly, IL-13 may in part be responsible for the T-cell-induced up-regulation of CDw60, because anti-IL-13 partly neutralized this effect of the T cell supernatant. In conclusion, CDw60 expression on psoriatic epidermal keratinocytes is likely induced by intralesionally activated T cells and may in part be due to IL-13. These findings would represent a novel mechanism by which T cells participate in the pathogenesis of psoriasis.

Antibodies↗
PubMed1997

Pemphigus foliaceus: preferential binding of IgG1 and C3 at the upper epidermis.

The immunopathological mechanism of pemphigus foliaceus acantholysis remains controversial. Previous workers have found that IgG autoantibodies are reactive with the epidermal surface and capable of blister induction. The presence of complement components in lesions also suggests their potential role in this disease. Complement participation, however, has not been clearly demonstrated. We describe a case of pemphigus foliaceus (PF) in a 58-year old woman which was confirmed by histopathological and immunopathological studies, and by ELISA assay on recombinant PF antigen. Unusual features of this case include the predominance of IgG1 anti-epithelial antibody in both the deposits and circulation, and the preferential binding of IgG and complement component 3 at the upper epidermis. We believe that this pattern of co-localized deposition suggests a location-specific, non-random complement activation.

Autoantibodies↗
PubMed1997

Treatment of refractory epidermolysis bullosa acquisita with extracorporeal photochemotherapy.

Treatment of epidermolysis bullosa acquisita (EBA) with conventional therapy frequently does not result in improvement. Extracorporeal photochemotherapy (ECP) is a novel immunomodulating technique which might be of benefit in the treatment of autoimmune disease. We prospectively studied three patients with refractory EBA who were treated with ECP. All three patients had improvement in objective measurement of their disease severity while two of the three had significant subjective improvement in their skin fragility and the clinical activity of their disease. Both the objective and subjective manifestations of the disease continued to improve 6 months after completion of the protocol. ECP may be therapeutic option in the treatment of patients with EBA who are refractory to conventional therapy.

Aged↗
PubMed1997

Nonsecretory IgA1 autoantibodies targeting desmosomal component desmoglein 3 in intraepidermal neutrophilic IgA dermatosis.

Intraepidermal neutrophilic IgA dermatosis, a rare skin disease entity manifested with blisters and pustules clinically and lower epidermal blister, acantholysis, and neutrophilic infiltration pathologically, was first reported in 1985. Although the disease is characterized by IgA autoantibodies targeting the epithelial cell surface component, the target antigen has not been determined. We investigated a patient with this disease by histopathology, direct and indirect immunofluorescence, immunoblotting, and immunoadsorption studies. The pustular lesion was characterized by blister at the lower epidermis, acantholysis, and neutrophilic infiltration. Nonsecretory IgA1 subclass autoantibodies targeting the lower epithelial cell surfaces were detected in the patient's skin and serum. The patient's IgA autoantibodies labeled a recombinant desmosomal protein desmoglein 3 on immunoblotting and the immunolabeling of epithelial cell surfaces was eliminated by preadsorption with desmoglein 3. Thus, desmoglein 3 is identified as a target antigen in intraepidermal neutrophilic IgA dermatosis. The ability of IgA1 autoantibodies to bind neutrophils may be responsible for the prominent neutrophilic infiltration observed histopathologically and for the pustular lesions observed clinically.

Aged↗
PubMed1996

The 105-kDa basement membrane autoantigen p105 is N-terminally homologous to a tumor-associated antigen.

Certain constitutive skin basement membrane components, such as bullous pemphigoid antigens and epidermolysis bullosa acquisita antigen, were discovered because they were targeted by an autoimmune reaction. We aimed to purify and characterize a 105-kDa skin basement membrane protein termed p105 recognized by autoantibodies (anti-p105) from patients with a unique immune-mediated subepidermal blistering skin disease. A simian virus 40-transformed human fibroblast cell line that synthesizes and secretes p105 was utilized as the protein source. p105 was partially purified by salt-gradient fractionation of serum-free conditioned medium through a Mono Q anion-exchange column and by examining each fraction with protein staining and immunoblotting against anti-p105. p105 was isolated from polyacrylamide gel electrophoresis gels, blotted onto polyvinylidene difluoride membrane, and subjected to protein microsequencing. The 20 microsequenced N-terminal amino acids exhibited no homology to known basement membrane proteins but exhibited a 70% homology to a 90-kDa tumor-associated antigen. Antibodies raised against a peptide generated from these amino acid sequences reacted to a 105-kDa western-blotted keratinocyte and fibroblast protein and a basement membrane component. p105 resisted digestion by glycosidases chondroitinase ABC, neuraminidase, and N-glycosidase F but was cleaved by protease V8 to antigenic fragments of 22 kDa and 14 kDa. The synthesis of p105 was inhibited by cycloheximide. We conclude that p105 is a unique basement membrane component produced by both keratinocytes and fibroblasts.

Amino Acid Sequence↗
PubMed1995

Linear IgA bullous dermatosis. Characterization of a subset of patients with concurrent IgA and IgG anti-basement membrane autoantibodies.

BACKGROUND AND DESIGN: The term linear IgA bullous dermatosis defines an immune-mediated blistering skin disease characterized by pruritic blisters, subepidermal separation with neutrophilic infiltration, and linear IgA antibody deposition at the basement membrane zone (BMZ). However, some patients with linear IgA bullous dermatosis demonstrate both IgA and IgG anti-BMZ autoantibodies on immunofluorescence. We describe four such patients and attempt to define this group of patients by studying their clinical, histopathologic, immunopathologic, immunoultrastructural, and immunochemical characteristics. RESULTS: Clinically, all four patients had a generalized pruritic blistering skin disease consistent with linear IgA bullous dermatosis. Histopathologically, all four cases demonstrated subepidermal blister formation with a predominantly neutrophilic dermal infiltrate. Immunopathologically, tissue-bound IgA (in four of four patients) and IgG (in three of four patients) antibodies were detected at the BMZ. Circulating IgA (in four of four patients) and IgG (in four of four patients) labeled the epidermal BMZ of normal human skin fractured at the lamina lucida and did not label the dermal BMZ. By immunoblot analyses, IgA (in three of three patients) and IgG (in one of three patients) circulating antibodies labeled the 97-kd linear IgA bullous dermatosis antigen. By direct immunoelectron microscopy, IgA and IgG antibodies were localized (in two of two patients) exclusively within the upper lamina lucida of the BMZ. CONCLUSIONS: Four cases of an immune-mediated blistering skin disease typical for linear IgA bullous dermatosis demonstrated both IgA and IgG anti-BMZ autoantibodies against the linear IgA bullous dermatosis antigen within the upper lamina lucida. We conclude that linear IgA bullous dermatosis should include a subgroup of patients with both IgA and IgG anti-BMZ autoantibodies.

Adult↗
PubMed1995

A nonscarring sublamina densa bullous drug eruption.

The term bullous drug eruption connotes several heterogeneous diseases in which blisters occur as a complication of the administration of drugs. Blisters may occur in bullous erythema multiforme, fixed drug eruption, or severe dermatitis medicamentosa with blisters. The common denominator is thought to be a hypersensitivity reaction to a systemic medication. Nevertheless, little has been written about the blisters in these disorders, and neither common nor distinct pathogenic mechanisms have been proposed. We describe a patient who had a rapidly progressive bullous eruption that occurred within hours of receiving intravenous trimethoprim-sulfamethoxazole. Routine histologic study of lesional skin demonstrated subepidermal blisters. Transmission electron microscopy and immunomapping of various basement components revealed that the cleavage plane of the blister was well below the lamina densa. After healing of the blistering process, no scarring or milia formation was observed.

Basement Membrane↗
PubMed1995

Failure of technetium-99m hexamethylpropylene amine oxime leukocyte scintigraphy in the evaluation of children with suspected appendicitis.

To determine the accuracy and reliability of a labeled leukocyte imaging technique in the early diagnosis of pediatric appendicitis, we prospectively studied patients presenting to the pediatric emergency department with abdominal pain suggestive of appendicitis. Patients scheduled for urgent laparotomy were excluded, as were postmenarchal females. Blinded interpretations by two independent radiologists were compared with surgical findings, if managed operatively, or with discharge diagnoses and three week follow-up, if managed medically. Twenty-three children underwent technetium-99m hexamethylpropylene amine oxime (HMPAO) leukocyte scintigraphy. Seven had pathologically proven appendicitis, with false negative interpretations made in three and five cases by the two radiologists. Sixteen patients had prompt resolution of symptoms; however, scintigraphic abnormalities were identified in 10 and seven cases by the two radiologists. Resulting sensitivity, depending on the individual reader, ranged from 29 to 57%, with specificity 38 to 56%, positive predictive value 22 to 29%, negative predictive value 64 to 67%, and accuracy 43 to 48%. Interrater reliability for agreement on the scintigraphic diagnosis of appendicitis was poor (kappa = 0.38). Technetium-99m HMPAO leukocyte scintigraphy was neither accurate nor reliable as a diagnostic tool in a subgroup of pediatric patients with an initial clinical presentation equivocal for appendicitis. This finding contradicts previously published experience using similar scintigraphic techniques.

Abdominal Pain↗
PubMed1995

A newly identified 105-kD lower lamina lucida autoantigen is an acidic protein distinct from the 105-kD gamma 2 chain of laminin-5.

A 105-kD lower lamina lucida antigen (p105) has been detected by autoantibodies (anti-p105) from patients with a novel immunobullous disease. To distinguish p105 from other known lamina lucida components, we performed comparative immunoblotting on purified human amniotic laminin-5 (kalinin), 804G matrix (enriched in laminin-5), and keratinocyte and fibroblast proteins using anti-804G matrix antibody (J-18) and anti-p105. J-18 labeled the truncated laminin-5 gamma 2 chain in amniotic laminin-5, 804G matrix, and keratinocyte conditioned medium, but did not label fibroblast cytosol. Conversely, anti-p105 did not label amniotic laminin-5 or 804G matrix, but did label p105 in both keratinocyte conditioned medium and fibroblast cytosol. J-18 labeled the 105-kD laminin-5 gamma 2 chain in reduced keratinocyte proteins and a 400-kD laminin-5 complex under non-reducing conditions. In contrast, anti-p105 labeled p105 under both reducing and non-reducing conditions but did not label a 400-kD protein complex. Similarly, comparative immunoblotting on keratinocyte proteins using anti-p105 and anti-laminin-1 revealed no commonly labeled protein bands. Electrophoretic fractionations by preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting of these fractions revealed that the peak fractions of keratinocyte proteins reactive with anti-p105 are different from those reactive with J-18. Furthermore, keratinocyte proteins fractionated by Mono Q anion-exchange chromatography revealed fractions immunoreactive with anti-p105, whereas J-18 showed no reactivity with these fractions. Two-dimensional gel electrophoresis and immunoblotting with anti-p105 revealed p105 to be an acidic protein with isoelectric points between 5.7 and 6.3, distinct from the isoelectric points of laminin-5 gamma 2 chain. We conclude that p105 is an acidic protein located in the lamina lucida and distinct from the truncated laminin-5 gamma 2 chain and the laminin-1 family.

Autoantigens↗
PubMed1995

Defective in vivo expression and apparently normal in vitro expression of a newly identified 105-kDa lower lamina lucida protein in dystrophic epidermolysis bullosa.

We have previously identified a novel 105-kDa lower lamina lucida protein detected by the autoantibodies from a group of patients who developed a unique immune-mediated subepidermal bullous dermatosis. We sought to determine if this novel basement membrane zone (BMZ) protein is normally expressed in the skin of patients with various subsets of epidermolysis bullosa (EB). Indirect immunofluorescence microscopy performed on non-lesional skin sections from patients with three major EB subsets revealed absence or significantly reduced expression of this novel BMZ protein in 20 out of 23 skin sections from patients with generalized dominant and recessive dystrophic EB. However, immunoblot analyses with the autoantibodies on Western-blotted proteins revealed that a comigrating 105-kDa protein is present in both cytosol extracts (n = 6) and conditioned media (n = 3) of cultured dermal fibroblasts derived from patients with dystrophic EB, as well as those cultured from two healthy individuals. Although the reason for such disparate findings is not known, the defective in vivo expression of this novel 105-kDa protein in dystrophic EB is presumably not due to a failure of fibroblasts to synthesize or secrete the protein. It is possible, however, that the 105-kDa protein may be unable to incorporate into the BMZ because it is produced in a dysfunctional form, or its BMZ binding site is missing. It is also possible that other structural alterations in skin BMZ, which occur in dystrophic EB, result in masking of the antigenic binding by the autoantibody when intact BMZ is probed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗