Influence of HTLV-1 on the clinical, microbiologic and immunologic presentation of tuberculosis

Abstract

BackgroundHTLV-1 is associated with increased susceptibility to Mycobacterium tuberculosis infection and severity of tuberculosis. Although previous studies have shown that HTLV-1 infected individuals have a low frequency of positive tuberculin skin test (TST) and decreasing in lymphoproliferative responses compared to HTLV-1 uninfected persons, these studies were not performed in individuals with history of tuberculosis or evidence of M. tuberculosis infection. Therefore the reasons why HTLV-1 infection increases susceptibility to infection and severity of tuberculosis are not understood.The aim of this study was to evaluate how HTLV-1 may influence the clinical, bacteriologic and immunologic presentation of tuberculosis.MethodsThe study prospectively enrolled and followed 13 new cases of tuberculosis associated with HTLV-1 (cases) and 25 patients with tuberculosis without HTLV-1 infection (controls). Clinical findings, bacterial load in the sputum, x-rays, immunological response and death were compared in the two groups.ResultsThere were no differences in the demographic, clinical and TST response between the two study groups. IFN-γ and TNF-α production was higher in unstimulated cultures of mononuclear cells of case than in control patients (p < 0.01). While there was no difference in IFN-γ production in PPD stimulated cultures, TNF-α levels were lower in cases than in controls (p = 0.01). There was no difference in the bacterial load among the groups but sputum smear microscopy results became negative faster in cases than in controls. Death only occurred in two co-infected patients.ConclusionWhile the increased susceptibility for tuberculosis infection in HTLV-1 infected subjects may be related to impairment in TNF-α production, the severity of tuberculosis in co-infected patients may be due to the enhancement of the Th1 inflammatory response, rather than in their decreased ability to control bacterial growth.

Human T‐Cell Lymphotropic Virus Type 1 and associated diseases in Latin America

“…Human T‐cell Lymphotropic Virus type 1 is also associated with Tropical Spastic Paraparesis/HTLV‐Associated Myelopathy (TSP/HAM), a progressive neurological disorder. Infected patients also tend to have more severe forms of infectious diseases such as strongyloidiasis and tuberculosis . However, ATLL is the more dramatic condition linked to HTLV‐1, with a very bad prognosis and poor remission rates with current treatments .…”

MAIT cells are reduced in frequency and functionally impaired in human T lymphotropic virus type 1 infection: Potential clinical implications

“…HTLV-1 is also the causative agent of an aggressive type of lymphoproliferative disorder called Adult T-cell leukemia[7]. HTLV-1-infected subjects have also an increased susceptibility to Mycobacterium tuberculosis (Mtb) infection[8, 9], suggesting an immunological impairment[10]. The role of the various T-cell subsets in the immune response to infection HTLV-1 and how it influences the control or the development of disease is not fully understood.…”

Erythema Nodosum Caused by Mycobacterium tuberculosis in HTLV-1 Infected Patients

“…The association between tuberculosis and HTLV-1 infection has been reported for over 10 years, but the mechanisms for the increased susceptibility of HTLV-1 infected subjects to develop tuberculosis is not known, and most of these patients present pulmonary tuberculosis [8,11,23]. Erythema nodosum are not frequently reported in HTLV-1 [10,17].…”