Biomedical subjects
Publications and source records attributed to R L Baer.
Eruptions caused by poison ivy (see Cover) and related plants are almost always a form of allergic contact dermatitis. Usually they can be readily recognized because of their characteristic streak- or line-like appearance. They usually clear within one to three weeks unless there is continued exposure to the allergen. Local treatment suffices in mild to moderate cases, but in more severe cases systemic corticosteroids can be added.
Both Langerhans cells from BALB/c mouse epidermis and nonadherent, low density (LD) cells, obtained from collagenase-treated minced lymph node, are stimulatory for isolated T cells in syngeneic mixed lymphocyte reaction (SMLR). The method of preparation of LD cells influences whether Fc receptor (FcR) can be detected on them. Fc receptors on nonadherent LD lymph node cells can be detected only if the same procedure is employed as that for Langerhans cell isolation, i.e., Ig-free bovine albumin must be used during gradient centrifugation and EA rosetting must be done overnight at 4 degrees C. Thus, both FcR+ and FcR- LD lymph node cells, as well as FcR+ Langerhans cells, stimulate SMLR. Although Ig+ cells in the LD fraction also stimulate the SMLR, their removal does not affect the stimulating capacity of the LD lymph node fraction.
Papaverine hydrochloride taken by mouth in doses of 100 mg four to six times daily or in 150-mg timed-release capsules two or three times daily is often effective in significantly decreasing itching in patients with atopic dermatitis. When used orally, as described here, it does not appear to have beneficial effects in other itchy dermatoses. It should be used as adjuvant treatment in combination with other accepted forms of therapy, since it alone cannot reverse the chronic skin changes brought about by months or years of scratching and rubbing.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
We investigated the possible role of a defect in antigen-presenting cells in the acquired immunodeficiency syndrome (AIDS), by enumeration of Langerhans' cells, the epidermal antigen-presenting cells. These cells were stained for the characteristic markers, surface Ia antigen and surface ATPase activity. A significant reduction was observed in the number of stained cells per square millimeter of body-surface area in 24 patients with AIDS and either opportunistic infections (Ia, 258 +/- 34, and ATPase, 274 +/- 46) or Kaposi's sarcoma (Ia, 378 +/- 100, and ATPase, 530 +/- 26), as compared with 38 appropriate controls (Ia, 721 +/- 13, and ATPase, 693 +/- 12). Examination of six patients with an "AIDS-related complex" revealed significantly reduced numbers of Langerhans' cells per square millimeter; this reduction was more pronounced in staining for Ia antigen (306 +/- 69) than in staining for ATPase activity (517 +/- 101). Given the known role of Ia expression in antigen presentation, we suggest that functional alterations in Langerhans' cells, and perhaps also in antigen-presenting cells in tissues other than skin, may be involved in the pathogenesis of AIDS.
Cell surface receptors and antigens present on Langerhans' cells (LC) suggest a close relationship between LC and interdigitating cells (IDC) in lymph node sections or lymphoid dendritic cells (LDC) in cell suspensions. One of the reported differences is that Fc receptors (FcR) which are present on LC, are absent on LDC. This difference can at least partly be explained by a laboratory artefact: FcR on murine LC are irreversibly modulated by the Ig that contaminates the bovine albumin commonly used for gradients. Furthermore, the demonstration of FcR on murine LC requires prolonged exposure to EA at 4 degrees C. A significant percentage of nonadherent, low density, Ig- lymph node cells also express such FcR. These cells can stimulate syngeneic mixed lymphocyte reactions as can LC isolated from epidermis. Consideration of LC as cutaneous representatives of the accessory cell system led to an investigation of their numbers in epidermal sheets of patients with acquired immunodeficiency syndrome (AIDS). A marked reduction in Ia+, ATPase+, OKT6+ LC was found as compared to controls, suggesting that accessory cell deficiency may play a role in the extreme immunodeficiency seen in AIDS patients.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The effect of 750 rads of gamma radiation on the rate of return of epidermal Langerhans cells (LC) following suppressive doses of topical glucorticoids was studied in guinea pigs. Gamma radiation alone had no effect on the LC as assessed by staining for cell membrane ATPase activity and Ia antigen. It did, however, delay the expected return of Ia but not ATPase surface markers on the LC after perturbation with glucocorticoids. The delayed return of surface Ia antigen is possibly related to a radiation-induced defect in the production of a required lymphokine and/or in intracellular Ia transport. Although our data do not rule out a cytolytic effect of steroids on the LC, they do strongly suggest that, at least in part, glucocorticoids act on the LC by altering cell surface characteristics.
The combined effect of topical glucocorticoids and ultraviolet B (UVB) irradiation on ATPase+ epidermal Langerhans cells in vivo was investigated in the guinea pig model. Glucocorticoids did not significantly enhance the response to UVB radiation, in the dosage range from 90-550 mJ/cm2 of UVB, suggesting that both agents were acting in a similar fashion. The solvent ethanol, however, potentiated the effect of UVB exposure due, at least in part, to increased penetration of the UVB into the epidermis. The recovery of ATPase+ Langerhans cells was significantly slower after high (greater than 165 mJ/cm2) than after more moderate doses (90-145 mJ/cm2) of UVB radiation.
We have investigated the effect of ultraviolet-B (UVB) irradiation on the density of epidermal ATPase-positive Langerhans cells, and the modulation of this effect by indomethacin (IND). Depilated backs of albino guinea pigs were exposed to varying doses of UVB (10-550 mJ/cm2). Skin biopsies were taken serially. There was an UVB dose-dependent decrease in the density of dendritic epidermal Langerhans cells, as identified by their membrane ATPase activity. This was accompanied by thinning and shortening, or disappearance of dendritic processes. Such changes were followed by a gradual recovery of the cell density to preirradiation level by day 21. Despite the high doses of UVB given, the maximal decrease in the density of ATPase-positive cells was only 58%. Topical application of IND, a prostaglandin-synthetase inhibitor, after irradiation resulted in a decrease of the erythema; however, the decrease in the density of ATPase-positive cells was still observed. In contrast, guinea pigs that received IND topically prior to irradiation showed a decrease erythemal response, but failed to show any decrease in the density of ATPase-positive cells. Administration of IND orally for 3 days prior to UVB exposure did not prevent the decrease in the cell density. The protective effect of topical IND, applied prior to irradiation, may be explained by its in vitro absorbance at both the UVB and UVA ranges. Topical application of IND 20 min prior to exposure to UVB in 2 human subjects resulted in an increase in the minimal erythema dose, giving a sun protection factor of 1.6, which is comparable to that produced by an equimolar concentration of para-aminobenzoic acid solution. The sun-protective property of IND, together with its activity as a prostaglandin synthetase inhibitor, indicate that it potentially could be a useful sunscreen agent. Its clinical safety and efficacy, however, remain to be determined.
Langerhans cells are the body's outer-most immunologic bastion against harmful environmental substances. They are a dendritie bone-marrow-derived subgroup of the mononuclear macrophages and serve an important immune regulating function. Langerhans cells are the antigen-presenting cells in the epidermis and play an important role in the induction and elicitation of delayed allergic hypersensitivity reactions against contact allergens, microbial antigens in the skin and antigens formed by cutaneous tumors.
The effects of topical and systemic administration of various glucocorticoids on the density of epidermal Langerhans cells (LC) were studied in guinea pigs. Glucocorticoids, such as betamethasone dipropionate and valerate, caused a marked decrease in LC demonstrable by staining for cell membrane ATPase activity and Ia antigens. By electronmicroscopy, LC also showed morphologic alterations. The observed decrements in LC density correlated with the concentration and known vasoconstrictive potency of the glucocorticoids administered. The anti-inflammatory action of glucocorticoids in skin disorders may, at least in part, be through their ability to alter epidermal LC, thus interfering with the antigen-presenting functions of these cells.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
A 73-year-old man had developed a 27 x 60-mm seborrheic keratosis on his trunk. Some months previously, an 18 x 19-mm cauliflower-like area had developed within this seborrheic keratosis. Histologic examination showed a papillated squamous cell carcinoma in situ arising in a seborrheic keratosis. Seborrheic keratoses are the most common cutaneous neoplasms in man. Malignant changes are most unusual but should be suspected in lesions of unusual clinical appearance.