Clinical Profile, Treatment, and Outcome of Patients with Secondary Hemophagocytic Lymphohistiocytosis in Critically Ill Patients: A Prospective Observational Study.

Introduction: The objective of the study was to evaluate the clinical profile and outcome of patients with secondary hemophagocytic lymphohistiocytosis (HLH) in critically ill patients. Materials and methods: A prospective observational study was conducted where critically ill adult patients presenting with fever and bicytopenia were evaluated according to the HLH-2004 diagnostic criteria for the presence of secondary HLH. The underlying trigger, clinical profile, treatment, and outcome of patients with HLH were analyzed. Results: Of the 76 critically ill patients with fever and bicytopenia, 33 (43%) patients were diagnosed with HLH. The following triggers for HLH were identified: bacterial infections (23%), fungal infections (10%), viral infections (10%), parasitic infections (10%), autoimmune diseases (13%), and malignancy (8%). A total of 78% of the HLH cases received steroids, but the use of steroids was not associated with improvement in mortality. Conclusion: There is a high prevalence of HLH in patients presenting with fever and bicytopenia in critically ill adult patients. Infections were identified as the most common trigger of HLH. How to cite this article: Fazal F, Gupta N, Soneja M, Mitra DK, Satpathy G, Panda SK, et al. Clinical Profile, Treatment, and Outcome of Patients with Secondary Hemophagocytic Lymphohistiocytosis in Critically Ill Patients: A Prospective Observational Study. Indian J Crit Care Med 2022;26(5):564-567.

CD4+ CD25+ FOXP3+ T cell frequency in the peripheral blood is a biomarker that distinguishes intestinal tuberculosis from Crohn's disease.

BACKGROUND: Distinguishing between Crohn's Disease (CD) and Intestinal Tuberculosis (ITB) has been a challenging task for clinicians due to their similar presentation. CD4+FOXP3+ T regulatory cells (Tregs) have been reported to be increased in patients with pulmonary tuberculosis. However, there is no such data available in ITB. The aim of this study was to investigate the differential expression of FOXP3+ T cells in patients with ITB and CD and its utility as a biomarker. METHODS: The study prospectively recruited 124 patients with CD, ITB and controls: ulcerative colitis (UC) and patients with only haemorrhoidal bleed. Frequency of CD4+CD25+FOXP3+ Tregs in peripheral blood (flow cytometry), FOXP3 mRNA expression in blood and colonic mucosa (qPCR) and FOXP3+ T cells in colonic mucosa (immunohistochemistry) were compared between controls, CD and ITB patients. RESULTS: Frequency of CD4+CD25+FOXP3+ Treg cells in peripheral blood was significantly increased in ITB as compared to CD. Similarly, significant increase in FOXP3+ T cells and FOXP3 mRNA expression was observed in colonic mucosa of ITB as compared to CD. ROC curve showed that a value of >32.5% for FOXP3+ cells in peripheral blood could differentiate between CD and ITB with a sensitivity of 75% and a specificity of 90.6%. CONCLUSION: Phenotypic enumeration of peripheral CD4+CD25+FOXP3+ Treg cells can be used as a non-invasive biomarker in clinics with a high diagnostic accuracy to differentiate between ITB and CD in regions where TB is endemic.

T cell suppression in the bone marrow of visceral leishmaniasis patients: impact of parasite load.

Visceral leishmaniasis (VL) is a disseminated and lethal disease of reticulo-endothelial system caused by protozoan parasites Leishmania donovani and L. infantum, which are known to induce host T cell suppression. To understand the impact of parasite load on T cell function, the present was focused on parasite load with T cell function in bone marrow of 26 VL patients. We observed significant enrichment of forkhead box protein 3 (FoxP3)+ (P = 0·0003) and interleukin (IL)-10+ FoxP3+ regulatory T cells (Treg ) (P = 0·004) in the bone marrow (BM) of patients with high parasite load (HPL) compared with low parasite load (LPL). Concordantly, T effector cells producing interferon (IFN)-γ (P = 0·005) and IL-17A (P = 0·002) were reduced in the BM of HPL. Blocking of Treg -cell derived suppressive cytokines [(IL-10 and transforming growth factor (TGF)-ß] rescued the effector T cells and their functions. However, it was observed that TGF-ß levels were dominant, favouring Treg cell differentiation. Furthermore, the low ratio of IL-6/TGF-ß favours the suppressive milieu in HPL patients. Here we show the change in levels of various cytokines with the parasitic load during active VL, which could be helpful in devising newer immunotherapeutic strategies against this disease.

Exonal switch down-regulates the expression of CD5 on blasts of acute T cell leukaemia.

To date, CD5 expression and its role in acute T cell lymphoblastic leukaemia (T-ALL) have not been studied closely. We observed a significant reduction in surface expression of CD5 (sCD5) on leukaemic T cells compared to autologous non-leukaemic T cells. In this study, we have shown the molecular mechanism regulating the expression and function of CD5 on leukaemic T cells. A total of 250 patients suffering from leukaemia and lymphoma were immunophenotyped. Final diagnosis was based on their clinical presentation, morphological data and flow cytometry-based immunophenotyping. Thirty-nine patients were found to be of ALL-T origin. Amplification of early region of E1A and E1B transcripts of CD5 was correlated with the levels of surface and intracellular expression of CD5 protein. Functional studies were performed to show the effect of CD5 blocking on interleukin IL-2 production and survival of leukaemic and non-leukaemic cells. Lack of expression of sCD5 on T-ALL blasts was correlated closely with predominant transcription of exon E1B and significant loss of exon E1A of the CD5 gene, which is associated with surface expression of CD5 on lymphocytes. High expression of E1B also correlates with increased expression of cytoplasmic CD5 (cCD5) among leukaemic T cells. Interestingly, we observed a significant increase in the production of IL-2 by non-leukaemic T cells upon CD5 blocking, leading possibly to their increased survival at 48 h. Our study provides understanding of the regulation of CD5 expression on leukaemic T cells, and may help in understanding the molecular mechanism of CD5 down-regulation.

Programmed death-1+ T cells inhibit effector T cells at the pathological site of miliary tuberculosis.

Optimal T cell activation is vital for the successful resolution of microbial infections. Programmed death-1 (PD-1) is a key immune check-point receptor expressed by activated T cells. Aberrant/excessive inhibition mediated by PD-1 may impair host immunity to Mycobacterium tuberculosis infection, leading to disseminated disease such as miliary tuberculosis (MTB). PD-1 mediated inhibition of T cells in pulmonary tuberculosis and TB pleurisy is reported. However, their role in MTB, particularly at the pathological site, remains to be addressed. The objective of this study was to investigate the role of PD-1-PD-ligand 1 (PD-L1) in T cell responses at the pathological site from patients of TB pleurisy and MTB as clinical models of contained and disseminated forms of tuberculosis, respectively. We examined the expression and function of PD-1 and its ligands (PD-L1-PD-L2) on host immune cells among tuberculosis patients. Bronchoalveolar lavage-derived CD3 T cells in MTB expressed PD-1 (54·2 ± 27·4%, P ≥ 0·0009) with significantly higher PD-1 ligand-positive T cells (PD-L1: 19·8 ± 11·8%; P ≥ 0·019, PD-L2: 12·6 ± 6·2%; P ≥ 0·023), CD19+ B cells (PD-L1: 14·4 ± 10·4%; P ≥ 0·042, PD-L2: 2·6 ± 1·43%; not significant) and CD14+ monocytes (PD-L1: 40·2 ± 20·1%; P ≥ 0·047, PD-L2: 22·4 ± 15·6%; P ≥ 0·032) compared with peripheral blood (PB) of MTB and healthy controls. The expression of PD-1 was associated with a diminished number of cells producing effector cytokines interferon (IFN)-γ, tumour necrosis factor (TNF)-α, interleukin (IL)-2 and elevated apoptosis. Locally accumulated T cells were predominantly PD-1+ -PD-L1+ , and blocking this pathway restores the protective T cell response. We conclude that M. tuberculosis exploits the PD-1 pathway to evade the host immune response by altering the T helper type 1 (Th1) and Th2 balance at the pathological site of MTB, thereby favouring disease dissemination.

Study of clinical, biochemical and immunological factors determining stability of disease in patients with generalized vitiligo undergoing melanocyte transplantation.

BACKGROUND: Stability is considered the most important parameter before performing any melanocyte transplantation procedure in vitiligo; however, current criteria rely on the history given by the patients. OBJECTIVE: This study was undertaken to determine the clinical, biochemical and immunological factors determining stability of disease in patients with generalized vitiligo to facilitate better patient selection for melanocyte transplantation and to understand immunological mechanisms for disease activity. METHODS: Thirty-three patients with generalized vitiligo with < 10% body surface area involved were allocated to three clinical stability groups: Group 1 (stability > 3 months but < 1 year), Group 2 (≥ 1 year but < 2 years) and Group 3 (≥ 2 years). Melanocyte transplantation was done using suction blister epidermal grafting (SBEG) on a single patch. Blood was drawn for catalase estimation from all patients and from 10 healthy control subjects. A 3-mm punch biopsy was taken on the day of transplantation from the margin of the macule in the first five patients in each group for the immunohistochemistry of CD4, CD8, CD45RO, CD45RA and FoxP3. Those with ≥ 75% repigmentation at 6 months were labelled as responders. RESULTS: The success rate was 0% in Group 1, 37·5% in Group 2 and 77·8% in Group 3. The difference in the success rate between the groups was statistically significant (P = 0·005). The median period of stability was significantly higher in the responders compared with that in the nonresponders (P = 0·001). Catalase levels were not significantly different between patients in the three groups of cases and in controls, or between responders and nonresponders. Lesional CD8 cells were significantly higher in Group 1 compared with Group 3. The percentages of CD8 and CD45RO cells were significantly higher in the nonresponders compared with the responders. CONCLUSION: Along with clinical stability, the proportion of CD8 and CD45RO cells in skin biopsies might help to determine the stability of the disease and thereby predict the success of transplantation.

Frequency of T cell expressing Th1 and Th2 associated chemokine receptor in patients with renal allograft dysfunction.

Acute rejection of human renal allografts is a frequent, serious posttransplantation complication, occurring in up to 50% of recipients. Leukocyte recruitment is a central feature of acute allograft rejection. Chemokine receptors are expressed on leukocytes in a cell type-specific manner. Recently CCR5+ and CXCR3+ cells have been observed in allograft biopsy specimens of patients undergoing acute cellular rejection (ACR). Herein we investigated the expression of Th1 (CCR5, CXCR3, and CCR2) and Th2 (CCR4, CCR3, and CCR8)-associated chemokine receptors on CD4 and CD8 T-cell populations. We sought to correlate chemokine receptor expression in peripheral blood T-cell subsets with the types of graft dysfunction (biopsy-proven rejections). In the peripheral blood CD4+ and CD8+ T-cell populations of patients with graft dysfunction, we observed a high frequency of Th1-associated chemokine receptors CCR5+ and CCR2+ but not CXCR3.

Enrichment of invariant natural killer T cells in the bone marrow of visceral leishmaniasis patients.

Lipid antigens of Leishmania donovani like lipophosphoglycans are shown as a potent ligand for the activation of invariant natural killer T (iNKT) cells. It is reported that activation of iNKT cells augments the disease pathology in experimental visceral leishmaniasis (VL). In this study, we demonstrate the enrichment of iNKT cells in the bone marrow, one of the disease sites among patients with VL.

High concentration of adenosine in human visceral leishmaniasis despite increased ADA and decreased CD73.

Absence of an effective Th-1 response has been demonstrated as a major cause for the disease pathology among patients with visceral leishmaniasis (VL). Defining strategies to prevent the development of Th-2 response and/or initiate/activate effective Th-1 response may be of help to reduce the growing incidence of drug unresponsiveness. Adenosine, which is considered as an endogenous anti-inflammatory agent is generated in injured/inflamed tissues by the enzymatic catabolism of adenosine triphosphate (ATP), and it suppresses inflammatory responses of essentially all immune cells. The extracellular adenosine-producing pathway comprises two major enzymes CD39 (ATP → ADP → AMP) and CD73 (AMP → Adenosine). In contrast, the adenosine-degrading pathway contains only one major enzyme adenosine deaminase (ADA). Our study shows high concentration of adenosine in diseased condition, varying expression of enzyme involved in adenosine-producing (CD73↓) and adenosine-degrading (ADA↑) pathways. These are less studied in infections like VL but are very important in terms of endogenous regulation of immune response among patients.

Diffuse idiopathic hyperplasia of the sternocleidomastoid muscle in a child.

Unilateral diffuse or localized enlargement of the sternocleidomastoid muscle (SCM) is an event commonly seen in infancy, and is popularly known as 'sternocleidomastoid tumor'. The condition, which usually spontaneously resolves with or without physiotherapy, is due to a hematoma following a difficult labor. The muscle regains its elasticity and complete function. In some infants it resolves with fibromatous changes in the muscle leading to shortening, fibrosis and finally culminating in torticollis. We describe a case of idiopathic diffuse enlargement of unilateral SCM in a 12-year-old child without any functional compromise or torticollis. The histopathological and clinical characteristics differentiating it from more commonly described sternocleidomastoid tumor or fibromatosis coli are described. We believe this is the first case report of idiopathic hyperplasia of SCM.

Partial hepatectomy and total cyst excision is curative for localized type IV-a biliary duct cysts - report of four cases and review of management.

PURPOSE: With the increasing use of newer modalities such as CT cholangiography and MRCP offering an accurate delineation of the ductal anatomy of choledochal cysts, the incidence of type IV-A biliary duct cysts has increased. Although the management of the more common type I cysts is well established, that of type IV-A cysts is still controversial. The localized/unilobar variety of type IV-A cysts is a unique entity amenable to curative surgical management. METHODS: Between Jan 2000 and Jan 2005, 10 of 25 cases with choledochal cysts were diagnosed as having type IV- cysts. Four of these were localized or unilobar variants affecting only one lobe of the liver. Three cases had a left ductal involvement and one had a right ductal involvement of their intrahepatic component. We describe the presentation and curative surgical management of these patients with a unilobar variety of type IV-A cysts and discuss the management options for type IV-A cysts in the literature. RESULTS: One child with previous surgical treatment for presumed type 1 cyst, diagnosed as having a type IV-A right ductal cyst complicated with liver abscess, underwent right hepatectomy, two children had a left hepatectomy and one child had a left lateral lobectomy. All four children had uncomplicated intraoperative and postoperative courses. After 4-8 years' follow-up, all are symptom-free. There were no biliary tract or hepatic abnormalities on radiological surveillance with MRCP. CONCLUSIONS: In some series, the incidence of type IV-A choledochal cysts is equal to or higher than that of type 1 cysts. MRCP and intraoperative cholangiogram can help to confirm the anatomical varieties and associated ductal strictures. In the unilobar/uniductal varieties, complete cyst excision can be safely achieved in children through an additional hepatectomy/lobectomy. This can result in a curative status, leaving the child free from complications such as cholangitis, abscess, hepatolithiasis and the risk of biliary duct malignancy.

Occult neurovesical dysfunction with anorectal malformations.

OBJECTIVE: To evaluate for the occurrence of occult NVD in children with anorectal malformations (ARM) using urodynamic evaluation. METHODS: This prospective study was carried out on children with ARM prior to and following definitive procedure. Urodynamic studies were performed on the Phoenix Griffon machine (Albyn Medical) using Phoenix plus software. RESULT: Nineteen children in the age range of 3 months to 156 months (mean = 19.2) were included in this study. Among these 19 children 13 underwent re-evaluation after definitive surgery for ARM. There were 11(57.9%) males and 8(42.1%) females. Of the 19 children 14 (73.7%) were cases of high anorectal malformation (HARM) and 5 (26.3%) were cases of low anorectal malformation (LARM). Baseline evaluation done in 19 children revealed seven urodynamic patterns: Normal capacity, compliant without uninhibited contractions (UIC) (21.1%); Normal capacity, compliant with UIC (5.3%); Normal capacity, poorly compliant without UIC (5.3%); Normal capacity, poorly compliant with UIC (10.5%); small capacity, compliant with UIC (5.3%); Small capacity, poorly compliant with UIC (26.3%) and large capacity, complaint with UIC (26.3%). Thirteen patients were evaluated post operatively also and in only 23% (3 of 13) no change in urodynamic pattern were observed. In the remaining 76.9% (10 of 13) some changes in urodynamics pattern were observed. The deleterious changes observed were appearance of UIC in 30.8% (4 of 13), decrease in the bladder capacity in 23% (3 of 13) and decrease in bladder compliance in 15.4% (2 of 13). CONCLUSION: Only 9 of of the 19 patients had normal urodynamics pre-operatively and post-operatively 3 more patients worsened. Incidence of occult NVD is high in patients with ARM even in the absence of clinical and radiological evidence of vertebral or lower urinary tract abnormalities. Though there seems to be a high incidence of changes in the neurovesical functions of these patients following definitive corrective surgery for ARM only time will show whether this has any deleterious effect on the upper tracts.

Urethral duplication in association with anorectal malformation.

Urethral duplication is an uncommon congenital anomaly, not often reported, which may be partial or complete. Anorectal malformations are not as uncommon and they may be associated with a host of associated anomalies. However, the association of urethral duplication with anorectal malformation is rare; this report describes two such cases. In one case the intervening septum could be incised endoscopically and in the other case the duplicated urethra was excised.

Urodynamics-based evidence for the beneficial effect of imipramine on valve bladders in children.

AIMS: In an era, in which valve bladder is recognised as perhaps the single most important determinant of long-term outcome in patients with posterior urethral valves (PUV), an insight into the etiopathogenesis and management of valve bladders is warranted. The present study was designed to evaluate bladder dysfunction in PUV and to assess the response to imipramine in these patients, both subjectively and objectively, by serial urodynamic studies (UDS). METHODS: From 1998-2001, 30 patients with PUV who had documented bladder dysfunction on UDS were studied. Patients with non-compliant or unstable bladders were treated with imipramine (1.5 - 2 mg/kg). All the patients in the present study were 5 years or older and hence old enough to be toilet trained. Assessment of continence and side effects of the drug was done after 3 months and repeat UDS were done at 3-6 months, 1 and 2 years. RESULTS: On the basis of initial treatment, the patients were divided into 2 groups; a fulguration group (n = 10, 33.3 %) and a vesicostomy group (n = 20, 66.6 %). Symptomatic voiding dysfunction was present in 27 of the 30 patients (90 %). Two patterns of urodynamic abnormalities were noted in the present study; 1) unstable bladders with single or multiple uninhibited contractions (18/30 patients, 60 %), and 2) small capacity, hypocompliant, hypertonic bladder (12/30 patients, 40 %). Post imipramine therapy significant symptomatic improvement was noted in 16/30 patients. On serial UDS, there was a 18-20 % increase in maximum cystometric capacity (MCC) and 30-35 % increase in pressure specific bladder volume (PSBV) following one year of imipramine therapy in 16/30 patients and 11/30 patients, respectively. 4 patients failed to show any improvement in MCC and PSBV with imipramine, they had been initially diverted with vesicostomy and later required augmentation cystoplasty. CONCLUSION: Unstable bladders and those with marginal bladder capacity and compliance showed the best response to imipramine therapy. Fibrotic, small capacity, hypertonic bladders are less responsive to imipramine. However, a trial of imipramine therapy is still warranted in these patients, as only 4/12 (33.3 %) patients with fibrotic hypertonic bladders failed to show any response and ultimately required augmentation cystoplasty. Imipramine qualifies as an effective and cheap drug for valve bladders.

Diffuse intra-abdominal fibromatosis-report of a new entity with review of literature.

Fibromatosis, arare non-neoplastic spindle cell proliferation of unknown aetiology, can occur anywhere in the body. Though extra-abdominal sites are commonly involved, intra-abdominal fibromatosis has also been described. Described herein is an unusual case of diffuse intra-abdominal fibromatosis in a 9-year-old boy, who could not be salvaged despite extensive medical management.

Initial surgical treatment as a determinant of bladder dysfunction in posterior urethral valves.

Bladder function in patients with posterior urethral valves (PUV) has an immense impact on long-term continence and renal function. Bladder dysfunction was corelated with the initial surgical treatment in 67 patients with PUV treated between 1985 and 2000. Age at presentation, current age, duration of follow-up, initial surgical treatment (diversion or valve fulguration), trends of renal function tests, voiding disturbances, and changes in the upper tracts were recorded. Urodynamic studies were done in all patients to determine urine flow rates, residual volume, maximal cystometric capacity (MCC), bladder compliance, involuntary detrusor activity, and pressure-specific bladder volume (PSBV) at 30 cm water. The patients were divided into three groups depending on the initial treatment: fulguration (n = 38), vesicostomy (n = 25), and ureterostomy (n = 4). At the time of this study voiding symptoms persisted in 45 patients. Mean percent MCC (% MCC) was 62%, 96%, and 100% of normal in the vesicostomy, fulguration, and ureterostomy groups, respectively (P = 0.002). Large-capacity bladders were seen in 10.9% of patients, mostly in pubertal and post-pubertal boys who were treated initially by either fulguration or ureterostomy; vesicostomy adversely affected bladder capacity and compliance (P = 0.007). PSBV was decreased in 48% of patients in the vesicostomy group and was significantly lower in the other groups (P = 0.01). Mean percent PSBV was 75%, 95%, and 96% of normal in the vesicostomy, fulguration, and ureterostomy groups, respectively. Uninhibited contractions were present in 21 patients (14 in the vesicostomy group) (P = 0.01). The highest incidence of upper-tract deterioration was seen with %MCC below 60% of normal (P = 0.001). The predominant urodynamic patterns were: (1) fulgurated group: good-capacity, compliant bladder; (2) vesicostomy group: small-capacity, hyperreflexic bladder; and (3) ureterostomy group: good capacity, compliant bladder. Primary valve ablation is associated with better bladder function than vesicostomy and should be the treatment of choice in PUV. Also, vesicostomy and ureterostomy have distinctly different effects on bladder function.

Urinary-tract infection affects somatic growth in unilateral symptomatic hydronephrosis.

To assess whether symptomatic unilateral ureteropelvic junction obstruction (SUUPJO) affects somatic growth and, if so, the parameters associated with it, 61 children (54 boys and 7 girls) who underwent pyeloplasty for SUUPJO without any other associated urological abnormalities were retrospectively studied. Height was compared with standard growth charts and was considered to be affected if it was below 2.00 Z-score. Such children were considered group B and the rest group A. Mean (+/-SD) age at presentation and mean (+/-SD) split renal function (SRF) (%) of the affected kidney were 6.0 +/- 4.0 years and 27.3 +/- 13.2, respectively, for the entire group. Somatic growth was affected in 16 (12 boys, 4 girls) children (26.2%). Urinary tract infection (UTI) was the presenting symptom in 11 (69%) and 5 (11%) children in groups B and A, respectively. Impaired somatic growth had no association with age at presentation or SRF, but a significant association (P < 0.001) was found with UTI. The mean post-surgery height percentile (2.92 +/- 4.85) over a mean follow-up of 3.37 +/- 1.86 years was significantly (P < 0.005) better compared with pre-surgery height percentile (0.67 +/- 0.96) in group B, indicating catch-up growth after surgery. In SUUPJO, somatic growth is affected. Presentation with UTI has a significant association, and height significantly improves after surgery in these patients.

A clinicopathological study of acute necrotising jejunoileitis.

We describe a variety of acute necrotizing enteritis that is endemic to the Indian subcontinent. During the period 1992-1998, 18 cases of acute jejunoileitis (AJI) were managed. Only those in whom the diagnosis was confirmed at laparotomy have been included in this study. The most common symptoms were abdominal pain (100%), fever (77%), and blood in the stool (100%). A stricture following conservative treatment was present in 1 case. The mean age at presentation was 6.5 years (range 6 months-12 years); the male:female ratio was 1.2:1. All cases were seen during May-October. Routine investigations and X-ray films were nonspecific. Stool cultures did not show any clostridia, shigella, or salmonella. The jejunum was involved most commonly; 28% of patients did not require a bowel resection. Only 1 child presented with shock; the mortality was less than 5%. Short-bowel syndrome resulted in 1 patient due to extensive disease. The histopathologic features that were characteristic of the disease were patchy transmural mucosal necrosis extending centrifugally with submucosal edema, interstitial hemorrhage, type III hypersensitivity reaction, and extensive neovascularization. This type of AJI seen in South/Southeast Asia does not seem to be due a to bacterial infective etiology; immune mediation is suggested. The milder forms can be confused with dysentery. Mild forms of the disease can be managed conservatively, but carry the risk of developing strictures. This disease should be suspected in cases of prolonged dysentery during the summer and autumn months.

Reconstitution of naïve T cells and type 1 function after autologous peripheral stem cell transplantation: impact on the relapse of original cancer.

BACKGROUND: Phenotypic and functional reconstitution of T cells after peripheral blood stem cell transplantation (PBSCT) and its influence on posttransplant immune status is important in terms of immune surveillance and relapse of original cancer. We investigated the relationship between the dominant immune reconstitution pathway and the immune surveillance. We also tested the cytokine bias acquired by T cells after transplantation and its possible influence on relapse of original malignancy. METHODS: Immunophenotyping of naïve and memory T cells was performed by flow cytometry on patients who underwent PBSCT for various cancers. Cytokine production by peripheral memory helper (CD4) and cytotoxic (CD8) T cells was investigated at various pretransplant and posttransplant time points with fluorescein isothiocyanate-based intracellular cytokine assay after short-term in vitro mitogenic stimulation (phorbol myristate acetate + ionomycin). Data on T-cell subsets and polarized cytokines gamma-interferon (Ifn) and interleukin 4 produced by memory T cells were compared with that of healthy controls. RESULTS: The reconstitution of naïve T cells and gamma-Ifn-producing memory cells was significantly lower in patients who experienced relapse of original cancer within 1 year of PBSCT compared to those who showed no signs of relapse even after 2 years and compared to normal subjects. The results indicate that efficient reconstitution of naïve T cells and type 1 function of memory T cells are important in maintaining T-cell repertoire diversity after PBSCT. It also confers appropriate levels of immune surveillance against diverse neoantigens that evolve from residual tumor burden. The data reveal that chemotherapy-induced thymic injuries may impair regeneration of naïve cells that result in a naivopenic state in a susceptible host. CONCLUSIONS: The study highlights the importance of naïve T-cell reconstitution and points towards cell replacement strategies for improving immune surveillance after PBSCT.