High serum-soluble interleukin-2 receptor is not associated with the immunosuppression in diffuse cutaneous leishmaniasis.

Diffuse Cutaneous Leishmaniasis (DCL) is a rare complication of Leishmania aethiopica-induced cutaneous leishmaniasis which is associated with non-self healing and in vivo and in vitro antigen-specific non-responsiveness. Such antigen-specific unresponsiveness is also observed in visceral leishmaniasis (VL). The non-responsiveness seen in VL disease is believed to be due, in part, to serum-derived factors, including raised serum soluble IL-2 receptor (sIL-2R). Raised sIL-2R in serum was not a consistent feature of DCL in our study (range: 787-4546 U/ml) but was frequently observed in sera of patients with other dermatological disorders (range: 474-3313 U/ml) and some patients with the simple local cutaneous leishmaniasis (LCL; range: 556-4247 U/ml). The level of sIL-2R in the sera of DCL patients was not indicative of the disease state. Sera from DCL patients did not reduce proliferation of the IL-2-dependent CTLL cell line nor reduce PHA-driven mononuclear cell proliferation, although sera from VL patients could. Both DCL and VL sera could reduce the L. aethiopica-driven proliferation. Furthermore addition of serial dilutions of recombinant IL-2 to CTLL cultured in VL or DCL sera containing high sIL-2R levels did not alter the effect of such sera on proliferation. We conclude therefore, that raised sIL-2R in serum is not associated with the immunosuppression in DCL.