122 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table II Mean Density of Epidermal Langerhans Cells Density of HLA-DR-positive cells (cells/mm 2) Density of CDla-positive cells (cells/mm 2) Ethnicity/age Sun-exposed Sun-protected Sun-exposed Sun-protected Caucasian/old 705 + 104 700 + 115 745 + 154 748 + 120 Caucasian/young 721 + 119 682 + 62 810 + 121 755 + 134 African-American/old 625 -+ 71 638 + 70 640 -+ 71 656 + 55 African-American/young 729 + 39 709 -+ 59 713 + 80 762 -+ 61 body, and the interaction between age and ethnic background were statistically signif- icant (p 0.05). Figures 3a and 3b show representative photomicrographs of biopsies from the inner aspect of the upper arm and the outer aspect of the forearm of an older African-American subject stained for HLA-DR. Tissues stained for CDla showed similar histological patterns. Although 37 volunteers participated in this study, not all of the results were usable because some of the tissue preparations failed to stain adequately with anti-CDla anti- body. This may have been caused by nonspecific binding of the monoclonal antibody onto the glass vial used for staining. In the latter part of the study, we used DMEM with 10% bovine serum albumin as a diluent to prevent nonspecific absorption of the anti- CDIa antibody during the staining process. In addition, we also stained a tissue from one subject with a photodamaged skin in order to confirm the effect of photodamage on Langerhans cells. The decreased density and damaged morphology of Langerhans cells was apparent at the sun-exposed site with the photodamage by cumulative sunlight exposure (Figure 4a) as compared to the sun- protected site (Figure 4b). a) b) 1000 1000 80O 600 ß .• • 800 • m 600 '*- 400 E 200 z 0 0 Young Old Young I I J Black Old Old Young Old Young I I I I I Caucasian Caucasian Black Age / Ethnicity Age / Ethnicity Figure 2. (a) The number of HLA-DR + Langerhans cells for each ethnic and age group. (b) The number of CDla + Langerhans cells for each ethnic and age group. Langerhans cell density of the African-American elderly group is slightly lower than those of other groups (I sun-exposed site, IU sun-protected site).

CHRONIC ACTINIC EXPOSURE ON LANGERHANS CELLS 123 Figure 3. HLA-DR + Langerhans cells of an African-American subject (age 71) at (a) sun-protected site and (b) sun-exposed site. Statistically, no significant difference was found between sun-exposed and sun- protected sites (x 200, alkalinephosphatase anti-alkalinephosphatase staining). SKIN COLOR MEASUREMENT The mean color of subjects is shown in Table III. Data were not obtained from three Caucasian subjects. Color difference (AE) between the sun-exposed and sun-protected Figure 4. HLA-DR + Langerhans cells of a Caucasian subject (age 56) with photodamaged skin at (a) sun-exposed site and (b) sun-protected site. The number of Langerhans cells was reduced and the mor- phology was damaged (x200, alkalinephosphatase anti-alkalinephosphatase staining).