at a dermatology outpatient clinic of a tertiary care hospital dermatology outpatient clinic of a tertiary care hospital dermatology outpatient clinic of a tertiary care hospital dermatology outpatient clinic of a tertiary care hospital dermatology outpatient clinic of a tertiary care hospital Adverse cutaneous drug reactions (ACDR) form an Table 1 important clinical entity in dermatology practice and the List of drugs implicated in the causation of cutaneous adverse severity of such reactions vary from mild to fatal ones. Although Suspect drug Total number % of of cases total cases

Post-kala-azar dermal leishmaniasis (PKDL) is a dermal sequela of visceral leishmaniasis (VL), reported mainly from two regions - Sudan in eastern Africa and the Indian subcontinent, with incidences of 50-60% and 5-10%, respectively. Importantly, patients with PKDL are considered as reservoirs of VL, linking its eradication to effective control of PKDL. The etiopathogenesis of PKDL is presumably due to an immunological assault on latent dermal parasites. Immunological markers include IL-10, whose expression in skin and plasma of Sudanese patients with VL predicted onset of PKDL. Cell-mediated immune responses, notably restoration of IFN-γ production by antigen-stimulated lymphocytes are well documented in Sudanese PKDL, but remain ambiguous in the Indian form; recently, antigen-specific IL-10-producing CD8+ lymphocytes have been implicated in pathogenesis. In Indian PKDL, upregulation of intralesional IFN-γ and TNF-α is counterbalanced by IL-10 and TGF-β together with downregulated IFN-γ R1. Although IL-10 curtails excessive IFN-γ-mediated reactivity and ensures parasite survival, its cellular source remains to be confirmed, with infiltrating regulatory T cells (Tregs) being a likely candidate. Future functional investigations on Tregs and their interaction with lesional effector lymphocytes would be indispensable for development of immunomodulatory therapies against Leishmania infection.

IL-10-producing CD3+CD8+ lymphocytes are important protagonists in the immunopathogenesis of Indian PKDL.

Miltefosine increased the proportion of monocytes that have a pro-inflammatory phenotype, which was accompanied by an enhanced secretion of pro-inflammatory cytokines and increased levels of serum nitrite. The decrease in anti-inflammatory cytokine levels and serum arginase activity collectively indicated that miltefosine triggered a robust T-helper 1 response that facilitated parasite elimination.

Indian post-kala-azar dermal leishmaniasis (PKDL) is a low-frequency (5-10%) dermal sequela of visceral leishmaniasis (VL) caused by Leishmania donovani; importantly, affected individuals are speculated to be parasite reservoirs. Insight into its immunopathogenesis could translate into rational immunomodulatory therapeutic approaches against leishmaniases. In patients with PKDL (n=21), peripheral lymphocytes were analyzed for surface markers, intracellular cytokines, and lymphoproliferative responses using flow cytometry. In lesional tissue biopsies (n=12), expression of counter-regulatory cytokines (IFN-gamma and IL-10) and the T-regulatory transcription factor forkhead box protein 3 (Foxp3) was analyzed using reverse transcriptase-PCR, along with immunohistochemical detection (n=8) of CD3 and Foxp3 positivity. In patients with PKDL, circulating CD8(+)CD28(-) and antigen-induced IL-10(+)CD3(+) lymphocytes were increased and receded with treatment. CD8(+) lymphocytes showed impaired proliferative responses to L. donovani antigen (LDA) and phytohemagglutinin, which were reinstated after treatment. At presentation, the upregulated lesional IFN-gamma and IL-10 messenger RNA (mRNA), Foxp3 mRNA, and protein were curtailed after treatment. In Indian patients with PKDL, increased frequency of the CD8(+)CD28(-) phenotype, enhanced antigen-specific IL-10 production, and accompanying anergy of circulating lymphocytes suggest their regulatory nature. Furthermore, the concomitantly elevated lesional expression of Foxp3 suggests their possible recruitment into the lesional site, which would sustain disease pathology.