Human T-cell responses to secreted antigen fractions of Mycobacterium tuberculosis

Abstract

The T-cell response of human donors to secreted antigen fractions of Mycobacterium tuberculosis was investigated. The donors were divided into five groups: active pulmonary tuberculosis (TB) patients with minimal and with advanced disease, Mycobacterium bovis BCG-vaccinated donors with and without contact with TB patients, and nonvaccinated individuals. We found that patients with active minimal TB responded powerfully to secreted antigens contained in a short-term culture filtrate. The response to secreted antigens was mediated by CD4 ؉ Th-1-like lymphocytes, and the gamma interferon release by these cells was markedly higher in patients with active minimal TB than in healthy BCG-vaccinated donors. Patients with active advanced disease exhibited depressed responses to all preparations tested. The specificity of the response to secreted antigens was investigated by stimulating lymphocytes with narrow-molecular-mass fractions of short-term culture filtrate obtained by the multielution technique. Considerable heterogeneity was found within the donor groups. Patients with active minimal TB recognized multiple secreted targets, but interestingly, six of eight patients demonstrated a predominant recognition of a low-mass (<10-kDa) protein fraction which induced high levels of gamma interferon release in vitro. Only a few of 12 previously characterized secreted antigens were recognized by T cells isolated from TB patients, suggesting the existence of a number of as yet undefined antigenic targets among secreted antigens.

Comparison of Antigen‐Specific T‐Cell Responses of Tuberculosis Patients using Complex or Single Antigens of Mycobacterium tuberculosis

“…However, when tested for proliferative responses, the PBMC from only 19 patients responded significantly to the complex antigens of M. tuberculosis. The 16 remaining patients who did not respond to the complex antigens in the proliferative assay may have been in a more advanced/chronic stage of the disease, as suggested from other studies [38,39]. A possible explanation for this non-responsiveness could have been the recruitment of M. tuberculosis-specific T cells to the site of infection, leading to reduced frequency in the peripheral blood [40].…”

High Resolution Electroelution of Polyacrylamide Gels for the Purification of Single Proteins from Mycobacterium tuberculosis Culture Filtrate

“…Another approach has been to separate protein mixtures into narrow molecular mass fractions by the elution of whole SDS-PAGE gels and to use these fractions for the study of T-cell recognition. Screening of T-cell recognition by this approach has been used both in animal models of TB infections [15,16], as well as for human TB patients [17]. In these studies two molecular mass fractions recognised strongly by lymphocytes isolated from M. tuberculosis infected animals and TB patients were identified (5-10 kDa and 25-35 kDa).…”

Plant‐derived recombinant immune complexes as self‐adjuvanting TB immunogens for mucosal boosting of BCG

“…Thus, Ag85B is an immunodominant antigen associated with the acute infection in TB patients, while Acr is preferentially recognized by latently infected individuals (Roupie et al, 2007). Ag85B (and also Ag85A) is one of the most protective known MTB antigens (Boesen et al, 1995), used in several vaccine candidates currently in clinical trials (Kaufmann, 2012). The antigen 85 complex is a major secretion product of MTB during exponential growth (Wiker and Harboe, 1992) that, together with ESAT6, is repressed in the stationary phase (Rogerson et al, 2006).…”