Using reverse transcriptase polymerase chain reaction we showed that f
reshly plucked human anagen hair expressed both type 1 (80 kD) and typ
e 2 (60 kD) interleukin (IL)-1 receptor mRNAs. The IL-1 receptor type
1 was functional since after in vitro stimulation of plucked hair with
IL-1 alpha, we observed the induction of mRNA(s) for the inflammatory
cytokines IL-1 beta, tumour necrosis factor a and IL-6 as well as for
the chemokines monocyte chemotactic and activating factor and IL-8. I
n addition, the growth of dissected human anagen hairs in culture in v
itro was significantly and dose-dependently inhibited by IG la as a co
nsequence of hair bulb degradation. These observations, together with
those of other authors in IL-1 alpha transgenic mice evidence the inhi
bitory role of IL-1 on human hair growth. Therefore, in order to ident
ify individuals with high inflammatory potential in their hair follicl
e environment, we designed a rapid and simple assay to detect variatio
ns in the level of IL-1 alpha production in the overnight supernatant
of plucked hairs in culture. We observed that 32.7% of the specimens f
rom the volunteers tested (n = 116) could be considered highly inflamm
atory in terms of IL-1 alpha production. Altogether, these results sug
gest that in alopecia androgenetica, hair growth might be negatively i
nfluenced by IL-1, directly produced by the outer root sheath keratino
cytes. Consequently, identifying the 'inflammatory alopecic individual
' might be of clinical interest to discriminate among individuals for
whom anti-IL-1 strategies might be of therapeutic relevance.