Pathogen prevalence may determine maintenance of antigen-specific T-cell responses in HIV-infected individuals.
OBJECTIVE
To assess the effect of antigen-exposure on the T-cell repertoire in the chronic phase of HIV-infection.


METHODS
This is a prospective cross-sectional study.


METHODS
HIV-seropositive patients and immunocompetent controls from tuberculosis low and high-endemic countries were recruited. Mycobacterium tuberculosis (purified protein derivative; PPD)-specific CD4 T-cell responses were quantified directly from whole blood using flow-cytometric analysis of intracellular cytokines after specific stimulation. T-cell reactivity toward cytomegalovirus (CMV) or Staphylococcus aureus Enterotoxin B (SEB) served as control.


RESULTS
In a low-endemic region, HIV-seropositive patients showed lower frequencies of PPD-specific T cells compared to immunocompetent individuals. This was not due to a general loss of immunity toward recall antigens, as T-cell immunity toward CMV or SEB was preserved. In line with continuous antigen exposure, HIV-seropositive patients from a high-endemic region showed preserved PPD-specific T-cell frequencies that were not different from those found in HIV-seronegative controls. Likewise, both groups did not differ in recall T-cell responses toward CMV or SEB.


CONCLUSIONS
A lower prevalence and frequency of PPD-specific immunity is a typical feature of HIV-related immunosuppression in low-endemic regions. In contrast, PPD-specific responses are maintained in HIV-seropositive individuals in regions with high tuberculosis prevalence. This suggests constant skewing and restriction of specific T-cell immunity toward environmental antigens in HIV-seropositive individuals.
Department of Transplant and Infection Immunology, Saarland University, Homburg, Germany.
Alexandra
A
Schuetz
Jan
J
Dirks
Urban
U
Sester
Antelmo
A
Haule
Nyanda
N
Elias
Christof
C
Geldmacher
Erica
E
Sanga
Leonard
L
Maboko
Klaus
K
Reither
Michael
M
Hoelscher
Andreas
A
Meyerhans
Martina
M
Sester
D000328:Adult; D018791:CD4 Lymphocyte Count; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D005434:Flow Cytometry; D015658:HIV Infections / Q000276:immunology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D011446:Prospective Studies