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We report on cell kinetic data about in vivo and in vitro DNA-labelling of germinative keratinocytes in normal and psoriatic epidermis. In order to study the cell cycle and its component parts in psoriasis, information on duration of the DNA-synthesis phase, epidermal germinative growth fraction, as well as cell cycle time are of special interest. Comparison of various anti-psoriatics reveals that they have different effects on the cell cycle in psoriatic epidermis. This observation may be important for the development and analysis of new treatment schedules and their influence on psoriatic cell proliferation kinetics.

As shown in bilateral comparison studies addition of crude coal tar (T) to standard antipsoriatic therapy with dithranol and salicylic acid in white petrolatum (CVS) diminished the dithranol-irritation; consequently, accelerated application of increasing dithranol-concentrations shortened the duration of TCSV -therapy.

The combination of different antipsoriatics or treatment regimens should increase the therapeutic effect and reduce the adverse reactions. The combination of dithranol and tar (cignolin-salicyl-vaseline + tar, CSVT) reduces dithranol erythema and increases the antipsoriatic effect. CSVT treatment is highly effective, but patients tend to accept it less than other treatment regimens. On the other hand, Goeckerman therapy (tar + UV irradiation) is more accepted but less effective. Combinations of dithranol with UV irradiation or with tar and UV irradiation (Ingram regimen) are not advantageous. Dithranol and Goeckerman therapy are relatively secure treatment regimens, as they have been applied for more than 50 years without knowledge of significant late defects. PUVA therapy, although highly effective, is not superior to dithranol therapy. Even though PUVA therapy is more easily accepted than dithranol treatment, PUVA therapy should be applied only in severe cases. The combinations of aromatic retinoid with (selective) UVB irradiation (ReSUP) or with PUVA therapy (RePUVA) are highly effective. Retinoids can reduce the UV doses and most likely limit the risk of late damage. For routine treatment, ReSUP is preferable to RePUVA therapy.

This article deals with the immediate effect of infra-red (IR) irradiation on human skin. The cutaneous response to IR significantly differed from that to polychromatic UV rays. The IR erythema showed a reticular pattern and was monophasic. Minimal erythema (ME) appeared without latency and faded a few minutes later. Induction of IR-ME required a radiation doses about 15,000 times higher (187-295 J/m2) than was needed for UVB erythema. The maximum erythema also occurred immediately after exposure to IR and faded away within one to four hours. The response was biphasic in only one of 28 test persons. Histological studies revealed dilated vessels and perivascular accumulation of degranulated mast cells.

Regarding the keratin pattern of non-exposed skin, we found no significant qualitative or quantitative differences between 6 old persons (mean age 85 years) and 4 young adults (mean age 20 years). There was, however, a slight increase of proliferation keratins (K6, K16) in aged skin. In non-exposed skin taken from 6 old (mean age 70 years) and 5 young persons (mean age 37 years), longterm primary submersion cultures of keratinocytes did not show any significant differences as far as the classical parameters of growth behavior were concerned (i.e. plating efficiency, cell count, and labeled thymidine incorporation). In accordance with these findings, daily measurements of the thymidine kinase activity in the supernatants revealed discrete but not significant differences between keratinocytes in aged people and those in young persons.