The mechanisms underlying induction of UVB-induced immunosuppression are not fully understood, but tumor necrosis factor alpha (TNF-alpha) is suggested to play a central role. A single base pair polymorphism at position --308 in the promoter region of the TNF-alpha gene associated with an enhanced secretion of TNF-alpha has been identified in humans. We have therefore investigated the association of the --308 polymorphism with the risk of basal cell carcinoma (BCC) in humans. The frequency of TNF G and TNF A alleles among Caucasian patients with a previous BCC (n=191) and health adults (n-107) were compared. For the TNF--308 polymorphism there was significant association between the genotype or allele frequencies and having BCC. To determine whether patients with a previous BCC had an increased capacity to secrete TNF-alpha, mononuclear cells were stimulated with lipopolysaccharide. Mononuclear cells from patients with a previous BCC (n=15) demonstrated a significantly increased release of TNF-alpha upon stimulation with lipopolysaccharide (P<0.03) compared with mononuclear cells age-matched control subjects (n=16). Further studies of other polymorphisms of the TNF-alpha gene associated with increased TNF-alpha production and BCC and necessary.