l. donovani infections are widely prevalent in east africa and the indian subcontinent manifesting as a wide spectrum of clinical phenotypes ranging from subclinical infections to a potentially fatal visceral disease . visceral leishmaniasis ( vl ) is a parasitic febrile illness with a transient immune suppression state with leucopenia and increased il-10 secretion [ 14 ] . in the hiv / aids era , vl is considered an opportunistic infection as evidenced by emergence of hiv / vl coinfections [ 510 ] . vl successful treatment is characterized by improvement of the leucopenia with a decline in cd4 + t cells and conversion in the leishmanin skin test ( lst ) , a probable immunity surrogate marker . lst conversion probably indicates ( re ) constitution of transiently lost cell - mediated immunity against leishmania antigens [ 1 , 1116 ] . in vl , il-4 stimulation with il-10 overproduction leads to reciprocal inhibition of inf- production and polyclonal b - cells stimulation ( th2 immune response ) [ 1720 ] . more than fifty percent of successfully treated sudanese vl patients develop an inflammatory skin rash , called postkala - azar dermal leishmaniasis ( pkdl ) . a number of hypotheses have been put forward to explain the aetiology of pkdl : undertreatment , uvb light exposure , and ethnicity [ 1 , 2123 ] . lst conversion , high plasma and skin il-10 , high plasma levels of c - reactive protein and high tgf- during vl predict development , progression and severity of pkdl [ 20 , 24 , 25 ] . it start as th2 immune response in vl patients , pass through a mixed th1/th2 stage to be followed by a pure th1 response in cured patients [ 26 , 27 ] . the majority of pkdl patients heal spontaneously , with persistence in 15% with chronic lesions that are probably a reservoir of infection [ 22 , 28 , 29 ] . sodium stibogluconate ( ssg ) , liposomal amphotericin b ( ambisome ) , and immunochemotherapy ( ssg in combination with alum - precipitated autoclaved l. major vaccine ) are available treatment modalities [ 22 , 30 , 31 ] . immune reconstitution inflammatory syndrome ( iris ) is a well - documented phenomenon that follows immune reconstitution in hiv patients who have recently started haart . it is a stereotyped immune inflammatory state that is characterized by transient worsening or appearance of new symptoms / signs following successful treatment . iris has been described in patients with parasitic , bacterial , viral and autoimmune diseases [ 3238 ] . cd4 + counts and preexisting opportunistic infection are reliable predictors of iris development [ 3941 ] . the immune pathology of iris is largely determined by the infecting organisms where cd8 + t cells dominate lesions of viral origins ; granulomatous inflammation usually dominates iris of fungi , protozoa , and mycobacterial conditions [ 4250 ] . iris manifests when there is an abrupt shift from an anti - inflammatory and immuno - suppressive state mediated by tnf- and il-10 to a pro - inflammatory state mediated by variable levels of il-2 , il-12 and ifn- [ 38 , 5155 ] . an increase in cd4+/cd 8 + cells coupled with a reduction in treg cells and an exaggerated cytokines response lead to initiation and progression of iris [ 5661 ] . recently , pkdl was reported as an iris phenomenon from africa and europe in hiv / aids / vl co - infected patients [ 62 , 63 ] . this study aimed to present pkdl as a form of paradoxical iris in non - hiv / aids patients with plethora of cytokines production , granuloma formation , and delayed - type skin hypersensitivity reaction ( lst ) without activation of existing opportunistic infection . archived supernatant samples from in vitro stimulated pbmcs of thirty pkdl patients were selected from the samples bank of the institute of endemic diseases , university of khartoum . pkdl patients were enrolled in an immunochemotherapy study and were randomized to two study arms : patients in group i received four intradermal doses of 100  g alum - precipitated alm + bcg ( bcg 1/10th usual vaccine dose)/weekly plus daily sodium stibogluconate ( ssg ) . patients in group ii received daily ssg plus four doses of the vaccine diluent ( placebo ) . ssg was given intramuscularly / intravenously at a standard dose of 20  mg / kg body weight / day . the study protocol was reviewed and passed by the ethics and scientific committees of the institute of endemic diseases , university of khartoum and the ethics committee of the federal ministry of health , khartoum . samples were from patients who consented previously for the storage and use of their samples for further future testing . patients were enrolled in the study based on specific inclusion and exclusion criteria as described previously . pkdl patients were subjected to physical examination , pregnancy testing , dat / hiv serological test , skin biopsy , haematological and chemical tests , lst , ecg , and cytokines at screening ( d2 ) , during treatment ( d0 , d7 , d14 , and d21 ) and follow up ( d30 , d40 , d60 , and d90 ) periods . pbmcs were harvested using the density gradient centrifugation and were counted using trypan blue exclusion technique with a haemocytometer . pbmcs cultures were stimulated with soluble l. donovani antigen ; phytohemagglutinin ( pha ) as a positive contol , a third well was left without antigen or mitogen as a negative control . ifn- were measured using double sandwich technique as per manufacturer 's leaf - lets ( r&d systems , germany ) . five patients ( data not shown on table ) had low to undetectable il-2 , il12 , and ifn- levels on d-2 ( screening ) and d60 in response to soluble l. donovani antigen ( sla ) . the leishmanin skin tests ( lst ) changed significantly from nonreactive ( induration = 00  mm ) on d-2 to reactive ( induration = 8.0  1.4  mm ) on d60 . these patients most probably passed il-12 priming , il-2 stimulation and ifn- secretion ( pro - inflammatory stage ) , and are now in leishmanin skin reactivity ( memory ) and lesion healing . 107 , 118 , 116 and 129 ] showed low levels of il-2 and il-12 on d-2 and d60 . their ifn- was high on d-2 but dropped significantly on d60 in response to soluble l. donovani antigen ( sla ) . three ( 3/4 , 75% ) were lst reactive on d-2 and remained the same on d60 . it is probable that these patients passed il-12 priming / il-2 stimulation and were seen in ifn- secretion ( pro - inflammatory stage ) where activated macrophages eliminated the leishmania parasite / antigen paving the way for immune recovery ( lst conversion ) and healing ( table 1 ) . 121 , 123 and 102 ] had low il-2 and il-12 on d-2 and d60 , the ifn- levels increased significantly on d60 compared to screening levels in response to soluble l. donovani antigen ( sla ) and were accompanied by lst conversion . all three patients healed completely by d60 . these patients already passed il-12 priming / il-2 stimulation when screened and were slowly creeping into ifn- secretion ( pro - inflammatory stage ) and lst conversion and healing . alternatively , these patients probably passed the il-12 priming when screened and were not yet in the il-2 stimulation . il-2 stimulation was probably initiated later when immune - chemotherapy was started , leading to increased ifn- secretion and lst conversion and healing ( table 1 ) . 110 , 105 ] had high il-2 levels on d-2 that significantly drop on d60 , while their il-12 was low at both dates . their ifn- levels dropped significantly on d60 compared to their d-2 levels in response to soluble l. donovani antigen ( sla ) . one patient healed while the other did not and had to receive ambisome treatment for the lesions to heal . these patients passed the il-12 priming stage and were seen at the il-2 stimulation / ifn- secretion stage ( pro - inflammatory stage ) that is followed by ifn- reduction and lst conversion ( table 1 ) . 104 ] had high il-2 on d-2 that increased significantly on d60 , while il-12 was low through the follow up period . the ifn- level was markedly high on d-2 and dropped significantly on d60 with lst conversion . this patient was probably in il-2 stimulation / ifn- secretion with overlap of lst conversion and healing ( table 1 ) . it is evident that all patients in the alum / alm vaccine + bcg group passed the anti - inflammatory stage when screened ( low to absent il-10 ) , some were in the pro - inflammatory ( il-2/il-12/ifn- secretion ) with progression to lst conversion and healing by d60 . their lst mean induration was 8.3  1.7  mm ( median= 7  mm ) and was significantly different from d-2 lst induration ( p < 0.000 ) . some were in the il-2 stimulation / ifn- secretion / lst conversion / healing stage , while others had passed the il-2 stimulation stage and were in ifn-/lst conversion / healing . the ssg vaccine combination appears to be effective in eliminating the leishmania parasite / antigen relieving the immune paresis that was preventing healing in these patients . il-10 levels were uniformly low in response to soluble l. donovani antigen ( sla ) in all screening and follow up samples in all patients . the progression from an anti - inflammatory to a pro - inflammatory stage has been reported previously as a prerequisite for the development of iris in hiv / tb co - infected patients on haart [ 5154 ] . 109 , 106 , 103 , 101 , 130 , 115 and 127 ] had low il-2 and low il-12 on d-2 with similar levels on d60 except for one patient [ no . 106 ] who showed an increase in il-2 , a drop in ifn- with no lst conversion , and a complete healing by d60 . 109 , 106 , 103 , 101 , 130 , and 115 ] had high ifn- levels on d-2 , that is , in a pro - inflammatory stage . 109 , 106 , 103 , 101 , 130 ] showed marked to moderate drop in d-2 ifn- levels , while the other two [ 2/7 , 28.6% ; 115 , 127 ] had a significant increase in ifn- on d60 , that is , progressive ifn- secretion ( anti - inflammatory stage ) . the majority of the seven patients [ 87.5% ] were lst non - reactive on d-2 compared to 62.5% on d60 . the majority ( 85.7% ) of these patients healed completely by d60 . transient il-12 priming ) and the il-2 stimulation and were in the ifn- secretion stage when seen on d-2 . on d60 , some of these patients continued in ifn- secretion , while others dropped their ifn- with consequent lst conversion and healing ( table 1 ) . six patients had low to undetectable il-2 , il-12 , and ifn- in response to soluble l. donovani antigen ( sla ) on d-2with similar levels on d60 . the majority ( 5/6 ; 83% ) were lst non - reactive on d-2 and remained the same on d60 with only one healed patient . another patient ( 1/6 ; 17% ) who was strongly lst reactive on d-2 and remained the same on d60 ; he progressed to complete healing . the healed two patients probably passed the il-12 priming , the il-2 stimulation and ifn- production and were in lst conversion status with complete cure . immune paresis  state and were not able to mount il-12 priming , il-2 , and ifn- production / lst conversion and so exhibited no healing ( ? failure to progress to il-2 priming and il-12/ifn- secretion in these patients probably indicates a degree of parasite unresponsiveness to ssg leading to persistence of leishmania parasite / antigen and the observed immune paresis as evidenced by lack of lst conversion . ambisome was successful in overcoming the parasite unresponsiveness , which is indicated by lesions healing . 112 had low il-12 , high il-2 , and high ifn- and lst non - reactivity on d-2 . on d60 , the ifn- and il-2 drop was accompanied by lst conversion and healing . this patient probably passed il-12 priming and was in il-2 stimulation and ifn- secretion when screened . the ifn- drop , lst conversion and healing were achieved during the follow up period . this patient findings demonstrate the mirror - image pattern exhibited by il-2 and ifn- levels . 108 had low il-12 , high il2/ifn- on d2 , with il-2 remaining high on d60 with a drop in ifn- level lst conversion and healing . the high level of il-2 with low ifn- levels and lst conversion and healing needs explanation ! il-10 levels in response to soluble l. donovani antigen ( sla ) were uniformly low in all screening and follow up samples , that is , patients passed the anti - inflammatory state when screened . these patients overcame the anti - inflammatory stage , progressed to a pro - inflammatory in line with previous data on iris in hiv co - infected patients on haart [ 5154 ] . some of the patients in the ssg / vaccine diluent were in a state of immune paresis ( high leishmania antigen load ) and were unable to mount an il-12 priming and il-2/ifn- secretion / lst conversion and healing . as suggested previously , a state of parasite ssg - unresponsiveness could be a contributory factor in patients lingering in an immune paresis stage . ambisome treatment eliminated the parasite with reduction in leishmania antigenic load putting patients on the way to recovery . others in this group showed the typical natural history of pkdl healing , that is , passing il-12 priming and were seen in the il-2/ifn- secretion that was followed by lst conversion and healing . data from this study showed the clear dichotomy of immune response in pkdl patients as was previously reported . on the other hand , the levels of il-2 and case reports from africa and europe introduced pkdl as an immune reconstitution phenomenon in hiv / vl co - infected patients at the start of haart [ 62 , 63 ] . in this study we attempted to prove that pkdl is an iris phenomenon that develops in vl patients who go through a transient stage of immune depression . pkdl develops as a new disease entity with symptoms and signs that are mainly of skin origin and that are different from vl . cured vl patients become immune competent as evidenced by conversion of the lst at six months after treatment , around the same time of pkdl development . healing of pkdl lesions is a function of a change of immune responses from a mixed th1/th2 state ( anti - inflammatory ) to a pure th1 one ( pro - inflammatory ) . healing of skin lesions starts at the cellular level by antigen presentation , followed by il-12 priming , and il-2 secretion which facilitates expansion of the th1 population and ifn- and tnf- secretion . it is logical to assume that the sequence of events in pkdl healing is as follows : drug - induced parasite killing , antigen load reduction , il-12 priming followed by il-2 secretion that in turn induces ifn- secretion which augments the killing potential of the macrophages with production of nitric oxide and reactive oxygen intermediates . eventually , inflammation decreases and healing occurs with production of memory cells and a lifelong lst reactivity status . the data also points to the fact that the cytokine patterns of pkdl healing are stereotyped and the differences between drug - treated ( ssg ; ambisome ) , and immunochemotherapy - induced patterns are only quantitative . il-2 is most probably the initiating cytokine for the healing process in pkdl , a finding that may have future therapeutic implications . 
 in conclusion , pkdl is a form of paradoxical iris that emerges as a new disease entity following successful vl treatment and immune recovery . pkdl skin lesions are immune inflammatory in nature and respond adequately to immuno - chemotherapy . like iris , pkdl is an immune - mediated phenomenon with increased activation from antigenic exposure , granuloma formation , and skin hypersensitivity reaction ( lst conversion ) .
visceral leishmaniasis ( vl ) is a parasitic disease characterized by immune suppression . 
 successful treatment is usually followed by immune reconstitution and a dermatosis called post - kala - azar dermal leishmaniasis ( pkdl ) . 
 recently , pkdl was described as one of the immune reconstitution syndromes ( iriss ) in hiv / vl patients on haart . 
 this study aimed to present pkdl as a typical example of paradoxical iris in non - hiv / aids individuals . published and new data on the pathogenesis and healing of pkdl was reviewed and presented . 
 the data suggested that pkdl is a typical example of paradoxical iris , being a new disease entity that follows vl successful treatment and immune recovery . 
 pkdl lesions are immune inflammatory in nature with granuloma , adequate response to immunochemotherapy , and an ensuing hypersensitivity reaction , the leishmanin skin test ( lst ) . 
 the data also suggested that the cytokine patterns of pkdl pathogenesis and healing are probably as follows : an active disease state dominated by il-10 followed by spontaneous / treatment - induced il-12 priming , il-2 stimulation , and inf- production . 
 inf--activated macrophages eliminate the leishmania parasites / antigen to be followed by lst conversion and healing . in conclusion , pkdl is a typical example of paradoxical iris in non - hiv / aids individuals with anti - inflammatory cytokine patterns that are superseded by treatment - induced proinflammatory cytokines and lesions healing .