Primary paediatric TH1 immunodeficiency with BCGosis

Introduction: In tuberculosis (TB) endemic regions BCG vaccine is administered at birth in an effort to protect against neonatal tuberculous meningitis. However, this live vaccine facilitates overwhelming systemic infections by otherwise innocuous organisms in infants with cellular primary immunodeficiencies . Case Report: Our case is a seven month old infant who developed abscess at BCG vaccination site followed by disseminated BCG­osis and was diagnosed to have TH1 immunodeficiency. Conclusion: Dissemination following BCG vaccination warrants prompt investigation to diagnose primary immunodeficiency disorders in HIV seronegative individuals.


INTRODUCTION
Bacille CalmetteGuerin (BCG) -a live attenuated vaccine -is routinely given to neonates in settings where tuberculosis is endemic [1]. Immunodeficient individuals are at high risk of developing BCG related complications like regional adenopathy i.e BCGitis or disseminated disease i.e BCGosis [2][3][4]. Primary immunodeficiencies are a diverse group of hereditary disorders leading to impaired immune response that creates high susceptibility to mycobacterial infections. Mycobacterium. tuberculosis, BCG and nontuberculous mycobacterium (NTM) may cause a severe disease in patients with primary immunodeficiencies [5]. One such case is reported here.

CASE REPORT
A seven month old female child presented with an abscess at BCG vaccination site along with generalized lymphadenopathy. She was vaccinated with BCG one month after birth and there was no history of contact with tuberculosis. Family history suggested that her elder female sibling had developed BCG abscess following vaccination who later succumbed to cardiac disease and pneumonia at the age of eight years.
On examination the baby had normal developmental milestones, but was under weight. She had moderate pallor, generalized lymphadenopathy; the maximum size of lymphnode being two cm. She also had hepatosplenomegaly (liver five cm and spleen seven cm palpable below the costal margin). Chest was clear to auscultation. Haemogram revealed Hb 5.3 gm/dl, TLC 18,400/mm 3 , DLC : neutrophils 60%, lymphocytes 36%, eosinophils 04%, basophil 0%, monocytes 0%. platelet count 2.2×10 6 /mm 3 , Creactive protein (CRP) 55 mg/L. Mantoux test was negative. Chest Xray was normal. ELISA test for HIV was negative in the parents. CT scan of chest showed normal sized thymus. Aspiration cytology of the axillary lymph node revealed presence of large numbers of foamy histiocytes with negative imprints in the cytoplasm admixed with a paucicellular chronic inflammatory infiltrate dispersed in a necrotic background and raised the suspicion of a tubercular lesion. ZiehlNeelsen stain confirmed presence of acid fast bacilli ( Figure 1). Further the cytoaspirate was sent for mycobacterial culture and a resected node was subjected to histopathology examination. Lymphnode histopathology revealed poorly formed granulomas, good number of foamy histiocytes, along with neutrophils ( Figure 2) Ziehl Neelsen stain of tissue section revealed macrophages packed with AFB (acid fast bacilli) ( Figure 3). Culture in LowenstenJensen (LJ) medium showed growth of mycobacteria with flat, smooth, moist and white colonies in five weeks ( Figure 4). The isolate was sent to a NABL (National accredited bacteriology laboratory) accredited referral laboratory for species identification and drugs susceptibility.
This baby was treated with first line antitubercular drugs. The baby was kept under followup. After three months she showed no response to antitubercular drugs, no weight gain and persistent lymphadenopathy. Rather she developed prolonged diarrhea and measles, hence leading to suspicion of immunodeficiency.   The child was investigated for primary immunodeficiencies. Immunoglobulin profile revealed IgG 1723 mg/dl, IgA 129 mg/dl and Ig M 297 mg/dl, serum ADA was 25 U/L. Lymphocyte enumeration test revealed lymphocyte 47.01%, absolute T cell count 2840/µl , CD3+ T cells 50.24%, CD4+ T cells 71.63% and absolute CD4+ T cells 2064/µl, CD8+ T cells 23.47 %, absolute CD8+ T cells 676/µl. CD4+:CD8+ ratio was 1:3.05. Thus this panel of tests displayed a marked hypergammaglobulinemia, decreased absolute T cell count, CD3+ T cell count and absolute CD 4+ T cell count. Finally diagnosis of post vaccination BCGosis in primary T cell (TH1) immunodeficiency was made and bacterial isolate from culture was sent for drug sensitivity test. Specific T cell function tests or cytokine and CK receptor assay could not be done. The infant was continuing antituberculosis drug treatment. Nitro blue tetrazolium test was positive ruling out CGD (chronic granulomatous disease). The species was confirmed to be M. bovies (negative nitrate reductase activity and catalase positive) in a referral laboratory and drug sensitivity report revealed resistance to pyrazinamide. ATT was extended with modified regimen and the child is under follow up.

DISCUSSION
BCG vaccines and environmental NTM are known to cause severe diseases in immunocompromised children. It is less well known that otherwise healthy children may also be affected. Unlike classic immunodeficiency they don't have other associated symptomatic infections apart from salmonellosis in less than half of them [6]. Our patient had no other associated infection except BCGosis. The prevalence of idiopathic disseminated BCGitis in France has been estimated to be at least 0.59 cases per million children vaccinated 6 . While Chemli J et al. have reported a high frequency of severe adverse effects of BCG vaccination occuring in genetically immunodeficient children [7].
Immunological panel of our patient revealed hypergammaglobulinemia indicating hyper functioning B cells and thereby well functioning helper TH2 cells. There was persistence of AFB inside the macrophages as well as outside not responding to therapy. Thus there was a failure of activation of macrophages that is dependent on IFNγ released by TH1 cells. Therefore, in our case possible defect was with TH1 cells resulting in lack of IFNγ leading to inactivation of macrophages thereby facilitating persistence and multiplication of bacilli intracellularly. Further, lack of IFNγ exerts no inhibitory effect on TH2 cells resulting in unopposed TH2 activity. This results in hypergammaglobulinemia. Further evaluation could not be done due to non cooperation of the parents and ATT was extended with change of regimen.
Susceptibility to intracellular pathogens may develop from a range of different acquired or inborn defects in macrophage activation by IFNγ [8]. Patients with inherited deficiency of interleukin (IL)12/IL23IFNγ axis show increased susceptibility to invasive diseases caused by the intramacrophage pathogens such as Salmonellae and Mycobacteria. IL12/IL23/IFNγ axis consists of two complementary components, first an IL 12/IL23 component and second an IFNγ component. Calman Mac Lennon et al. have reported in their study that mycobacterial disease occurred in 77% cases wish IL12/IL23 component deficiency and in 94% cases with IFNγ component deficiency [9].
Predisposition to mycobacterium is called mendelian susceptibility to poorly virulent mycobacteria such as BCG and NTM. It is thought to be due to impaired immunity, specifically altering host defenses against Mycobacteria. This syndrome is characterized by parental consanguinity, familial forms and an autosomal recessive pattern of inheritance. The rarity and heterogeneity of the syndrome make the diagnosis difficult. Different types of mutation have been detected in four genes (IFNGRI, IFNGR2, IL12B, IL12RB1) resulting in eight different disorders whose common pathogenic mechanism is impaired IFNγ mediated immunity. Severity of the clinical phenotype depends on IL12 P40 the genotype. Complete IL12 40, IL12RB1 IL12RB1 deficiency and partial IFNγ R1 and IFNγ R2 deficiencies generally lead to curable infections with antibiotics supplemented with IFNγ. Complete IFNγ www.ijcasereportsandimages.com R1 and IFNγ R2 deficiencies predispose to overwhelming infections in early childhood which respond poorly to antibiotics and are ineffective to IFN γ treatment [5]. Bone marrow transplantation gives a possible hope while gene therapy is the treatment of choice.
Rapid diagnosis of complete IFNγR deficiency is essential for the planning of clinical management by determining serum IFNγ level by ELISA. High IFNγ level suggests complete IFNγR deficiency, where as low or undetectable level indicates IL12, IL12 R, partial IFNγR deficiency or undetermined defects. IL12 P40 deficiency can be diagnosed by ELISA, with low levels of IL12 P40, IL12 P70 and IFNγ secretion by stimulated peripheral blood mononuclear cells (PBMC) [6].
Acquired predisposition to mycobacterial disease due to autoantibodies to IFNγ has been reported by Beata Kampmann el al. [7]. In three patients they detected high titres of auto antibodies in three patients that specifically bind to IFNγ and inhibit its ability to activate macrophage function. All the cases had similar phenotype to that seen with mutation in the IFNγR path way and all presented with severe progressive NTM infection.
In our case all possible causes, for secondary immune deficiency were excluded. Positive nitroblue tetrazolium test ruled out the possibility of CGD, which should be suspected in all cases of BCGosis [3,10,11]. Other primary Tcell immunodeficiencies were excluded by absence of lymphocytosis, normal CD8+ Tcell counts, increased IgG (ZAP70 deficiency), eczema & thrombocytopenia (Wiskott-Aldrich syndrome), complex congenital cardiac and craniofacial defects. (Di George Syndrome), and hepatitis, haemophagocytic syndrome and aplastic anemia (Xlinked lympho proliferative disorder) [12]. Thus, with a similar history in the family primary immunodeficiency at the level of TH1 cell could be established.

CONCLUSION
Infection due to vaccination with BCG or non tuberculosis mycobacteria (NTM) may occur in patients with no hereditary or acquired immune deficiency. These idiopathic infections affect children or adults that are otherwise healthy thus make the diagnosis difficult. Clinicians should consider the possibility of defects at various levels of macrophage cell interaction and rapid diagnosis of complete IFNγR deficiency is essential for the planning of clinical management. Ideally all live bacterial vaccines should be avoided in such immunodeficient cases. *********

Author Contributions
Sitaram Mohapatra -Substantial contributions to conception and design, Acquisition of data, Analysis and interpretation of data, Drafting the article, Revising it critically for important intellectual content, Final approval of the version to be published Sudha Sethy -Substantial contributions to conception and design, Acquisition of data, Analysis and interpretation of data, Drafting the article, Revising it critically for important intellectual content, Final approval of the version to be published Pranati Mohanty -Substantial contributions to conception and design, Acquisition of data, Analysis and interpretation of data, Drafting the article, Revising it critically for important intellectual content, Final approval of the version to be published Ashoka Mohapatra -Substantial contributions to conception and design, Acquisition of data, Analysis and interpretation of data, Drafting the article, Revising it critically for important intellectual content, Final approval of the version to be published Sarita Pradhan -Substantial contributions to conception and design, Acquisition of data, Analysis and interpretation of data, Drafting the article, Revising it critically for important intellectual content, Final approval of the version to be published

Guarantor
The corresponding author is the guarantor of submission.