The Influence of Race and Phenotype on the Erythrocyte D Antigen Studied by I131--labeled Anti--D

A method for the preparation of I¹³¹-labeled anti-D eluates (I^[unknown] anti-D)specific for the D antigen by adsorption and elution from intact D positivered cells is presented. A standard D antigen reference system for the quantitative comparison of the red cell D antigen from various donors was developedon the basis of kinetic studies of the effect of pH, temperature and antigenconcentration on the I^[unknown] anti-D reaction with the D antigen. The red cell Dantigen determinations of the blood from 33 Negro and 102 Caucasiandonors showed wide monomodal frequency distributions which indicate aheterogeneity of quantitative D antigen reactivity consistent with previousserologic and I¹³¹-labeled anti-D studies. The average red cell D antigenreactivity of the 20 probable D homozygote and 14 established D hemizygoteCaucasian donors was similar to the D antigen reactivity of the 102 randomCaucasian donors. The red cell D antigen reactivity was strongly depressedby the C antigen (or C gene) in Caucasian bloods and enhanced by the Eantigen (or E gene) in Negro bloods. The E antigen (or E gene) may alsohave enhanced the D antigen reactivity in red cells from Caucasian donors,but the difference in D zygosity provides an alternative explanation for theresults. The marked influence on red cell D antigen reactivity in the presenceof the C and E antigen may well have obscured any lesser influence of Dzygosity.

Accepted on December 6, 1962     

The erythemal response of human skin to ultraviolet radiation

A reflectance instrument was used to measure objectively the erythemal response of human skin to ultraviolet radiation. Dose-response curves have been constructed for four radiation wavelengths. In each case, the measured increase in erythema was found to be linearly related to the logarithm of the dose of ultraviolet radiation. Significantly different slopes of response were obtained for radiation of 254 and 280 nm compared with 300 and 313 nm radiation. The relevance of these findings is discussed with relation to the mechanism of erythema production and the erythema action spectrum.     

A quantitative study of the effect of topical indomethacin on cutaneous erythema induced by UVB and UVC radiation

The effect of indomethacin gel on UVB and UVC erythema was assessed objectively using a reflectance instrument. When indomethacin was applied immediately after irradiation, UVR (ultraviolet radiation) dose-dependent suppression of erythema was demonstrated for both wavelengths until 36 h after irradiation when both indomethacin and control gel base-treated sites were equally erythematous. Suppression of erythema also occurred when application of indomethacin was delayed until 24 h after irradiation, showing that for both wavelengths prostaglandin synthesis remains increased throughout this period. The degree of suppression at any time, however, was no greater than that achieved by a single application immediately after irradiation, indicating that the eventual equal erythema of indomethacin and gel base-treated sites was not due to tachyphylaxis or inadequate dosage. Construction of dose-response curves for the indomethacin-responsive and indomethacin-unresponsive components of erythema shows that in human skin the difference in erythemal response to UVB and UVC radiation is not due to the formation of different mediators at these wavelengths.     

The permissive effect of sebum in seborrhoeic dermatitis: an explanation of the rash in neurological disorders

The hypothesis that sebum permits the growth of Pityrosporum ovale, and hence the development of seborrhoeic dermatitis, was tested by observing whether a reduction of sebum production by isotretinoin would improve the disorder. In 10 male patients with seborrhoeic dermatitis, treatment with isotretinoin for 6 weeks reduced the mean sebum excretion rate by 70% and improved the severity of the rash, but with a site difference in magnitude of response. It is concluded that the residual pool of sebum is important for the growth of P. ovale and that, within the physiological range, sebum has a permissive effect on the growth of this yeast. Variation in the pools of residual sebum explains a number of features of the disease such as site of involvement and greater prevalence in males than females. The pathological increase in the residual pool of sebum due to immobility explains the frequent occurrence of seborrhoeic dermatitis in patients with a variety of neurological disorders.     

The action spectrum between 320 and 400 nm for clearance of psoriasis by psoralen photochemotherapy

We have compared the effectiveness of oral 8-methoxypsoralen photochemotherapy (PUVA) using ultraviolet fluorescent lamps with peak emission at either 325, 352 or 370 nm in the treatment of 24 patients with psoriasis. The forearms of each patient were treated three times weekly with two of the three lamps. The erythemal sensitivity of each patient was tested before the first treatment to ensure that equally erythemal doses of radiation were given from each of the lamps. A side-to-side comparison was used to assess response to treatment at weekly intervals for the 6 weeks of the trial. The lamp with peak emission at 325 nm was shown to be significantly superior to either of the other lamps in terms of response assessed at weekly intervals, and time to clearance of psoriasis. An action spectrum, constructed from the median doses required for clearance of psoriasis using each of the lamps, showed that the effectiveness of the radiation decreased exponentially with increasing wavelength throughout the UVA waveband, such that radiation at 320 nm was an order of magnitude more effective than at 360 nm. This suggests that lamps with peak emission around 325 nm will be more effective than those conventionally used in PUVA units with a peak emission at 352 nm. Lamps with peak emission around 325 nm are also highly effective in the treatment of psoriasis with phototherapy alone. Thus a single treatment unit containing these lamps could be used either for PUVA or ultraviolet phototherapy of psoriasis, avoiding duplication or irradiation equipment.     

A portable instrument for quantifying erythema induced by ultraviolet radiation

The design and performance of an instrument for quantifying ultraviolet-induced cutaneous erythema are discussed. If the instrument is used to record an‘erythema index’ at a site on the skin before and after irradiation, the difference between those two readings is essentially related to an increase in vasodilation and is largely independent of the melanin content of the epidermis.     

PUVA treatment of scleromyxoedema

Treatment of a 60-year-old woman with scleromyxoedema with 8-methoxypsoralen and UV-A radiation (PUVA) resulted in significant clinical and histological improvement but no change in circulating paraprotein.