Bacterial infection might influence the clinical response of patients with immunological disorders including
psoriasis to the therapeutic efficacies of immunosuppressive drugs, but few studies have been carried out to investigate the implication of bacterial
superantigens. We evaluated the suppressive efficacies of
betamethasone butyrate propionate,
vitamin D3 derivatives, and
cyclosporine against
concanavalin A- or
superantigen-induced proliferation of peripheral-blood mononuclear cells obtained from 18 healthy subjects. In vitro
drug concentrations giving 50% inhibition (IC50s) of peripheral-blood mononuclear cell-proliferation stimulated with
concanavalin A or streptococcal pyrogenic
enterotoxin A were estimated. Concentrations of
tumor necrosis factor-alpha,
interferon-gamma,
interleukin-2, -4, -5, or -10, in a peripheral-blood mononuclear cell-culture medium were measured with beads-array procedures. The median (range) IC50 value for
betamethasone butyrate propionate evaluated in the streptococcal pyrogenic
enterotoxin A-stimulated peripheral-blood mononuclear cells was 291.6 (0.001-1171.5) ng/ml, which was significantly higher than the value 0.072 (0.01-222.5) ng/ml found in
concanavalin A-stimulated peripheral-blood mononuclear cells (P=0.0245). However, the median (range) IC50 value for
calcipotriol in the streptococcal pyrogenic
enterotoxin A-stimulated peripheral-blood mononuclear cells was 0.3 (0.24-1357.4) ng/ml, which was significantly lower than the value 128.6 (0.1-776.9) ng/ml found in
concanavalin A-stimulated peripheral-blood mononuclear cells (P=0.0323). The IC50 value for
cyclosporine was not significantly different between the
concanavalin A- and streptococcal pyrogenic
enterotoxin A-stimulated PBMCs. Concentration for none of the
cytokines was significantly different between
concanavalin A- and streptococcal pyrogenic
enterotoxin A-stimulated peripheral-blood mononuclear cell cultures. The effects of
betamethasone butyrate propionate to suppress these
cytokine productions were rather stronger than those of
calcipotriol. Streptococcal pyrogenic
enterotoxin A induced by hemolytic streptococci colonization is suggested to attenuate the therapeutic efficacy of
betamethasone butyrate propionate. While the mechanistic background of
calcipotriol to suppress streptococcal pyrogenic
enterotoxin A-induced peripheral-blood mononuclear cell-proliferation remains to be elucidated,
vitamin D3 derivatives appears to be effective in suppressing anomalistic immunity in patients having hemolytic streptococci colonization.