C3b receptor in normal human skin.

Receptors for C3b in normal skin were studied. C3b was produced by treating normal human serum with cobra venom factor and by partial digestion of purified C3 with trypsin. Cryostat sections of normal human skin were incubated with C3b, followed by a direct immunofluorescent technique using monospecific goat antihuman C3. The histologic localization of C3b fluorescence was ascertained by fixing cryostat sections with glutaraldehyde and staining with hematoxylin and eosin. The following structures showed staining with anti-C3: (1) endothelial cells in capillaries, larger vessels, and arteries, (2) smooth muscle in arrector pilori muscles and artery walls, and (3) myoepithelial cells in the secretory portion of sweat glands. C3b did not bind to the intercellular substance nor to the basement membrane zone in normal human skin. Normal human sera treated with EDTA, EGTA, and heat (56 degrees C for 30 min) were negative, as was purified C3 by itself, thus indicating that native C3 did not bind to these receptors. Specificity for C3/C3b was shown by blocking with both unconjugated rabbit antihuman C3 and purified C3. The endothelial C3b receptor may have an important role in the localization of immune complexes in cutaneous vasculitis.

Cowden's disease (multiple hamartoma syndrome).

Cutaneous and oral lesions appearing as verrucous papules are a regular and diagnostic finding in Cowden's disease. The lesion occur predominantly over the central portion of the face, concentrated around orifices, lips, gingiva, and tongue, and over the acral portions of the upper extremities. These skin lesions have been found to be associated with fibrocystic breast disease, carcinoma of the breast, thyroid tumors, ovarian cysts, gastrointestinal polyposis, fibromas, angiomas, and lipomas. It is important to be able to distinguish the skin lesions from simple verruca vulgaris because they serve as a cutaneous marker for existing or potential internal malignancy, especially of the breast and thyroid.

C3b receptor in normal human oral mucosa.

The presence of a receptor for C3b in normal human oral mucosa was studied using C3b produced by treating normal human serum with cobra venom factor. Cryostat sections of normal human oral mucosa were incubated with C3b, followed by a direct immunofluorescence technique using monospecific goat-antihuman C3. The histologic localization of C3b fluorescence was determined by fixing cryostat sections with glutaraldehyde and staining with hematoxylin and eosin. The endothelial cells of the capillaries and smaller venules in the oral mucosa showed staining by anti-C3. C3b did not bind to the intercellular substance nor to the basement membrane zone of normal human oral mucosa. Normal human serum treated with EDTA was negative, thus indicating that native C3 did not bind to the receptor. The endothelial C3b receptor of the oral mucosa may have an important function in the localization of immune complexes that occur in systemic diseases, as well as in diseases restricted to the oral mucosa.

Familial cutaneous leiomyomatosis.

A 24-year-old Caucasian man was evaluated because of a history of multiple firm, reddish, papulonodular skin lesions occurring over the buttocks, thighs, and lower portions of his back and legs since the age of 17 years. Most lesions had developed within 1 year of onset and had become very painful. The family history revealed that the patient's mother and maternal aunts had similar skin lesions. The mode of inheritance is that of autosomal dominant pattern. The mother and three maternal aunts all had had hysterectomies. Biopsy specimens of skin lesions with hematoxylin-eosin and Masson-trichrome stains showed typical leiomyoma. Bodian's staining method revealed an increased amount of nerve fibers interlacing within muscle fibers and in the surrounding tissue. This finding may explain the painful nature of the cutaneous leiomyomas. Treatments consist of analgesics for control of pain and selective excision of larger painful leiomyomas.

Granuloma annulare: histopathologic and direct immunofluorescent study.

Eighteen cases of granuloma annulare were classified histopathologically and examined by direct immunofluorescence. The three different histopathologic types of granuloma annulare were compared with the result of immunofluorescence examination. No features of leukocytoclastic vasculitis were seen. Direct immunofluorescence of granuloma annulare does not reveal any consistent diagnostic pattern. Dermal desposition of fibrin in necrobiotic areas were noted in 8 cases of 18. Blood vessel and/or basement membrane deposition of IgM and C3 was inconsistent and does not support an immune complex vasculitis. Direct immunofluorescence is useful in studying the pathogenesis of granuloma annulare. The finding of fibrin, together with the histology, suggests to us a delayed hypersensitivity reaction as the dominant pathogenic event.