Am. J. Respir. Crit. Care Med., Vol 152, No. 6, 12 1995, 2000-2004.
Impaired natural immunity to pneumolysin during human immunodeficiency virus infection in the United States and Africa
BM Amdahl, JB Rubins, CL Daley, CF Gilks, PC Hopewell and EN Janoff
Department of Medicine, Veterans Affairs Medical Center, USA.
Human immunodeficiency virus (HIV) infection is associated with a
significantly increased incidence of pneumococcal pneumonia and concomitant
bacteremia. We hypothesized that the predisposition of HIV- infected
patients to invasive pneumococcal infection may be related, in part, to an
impaired immune response to the pneumococcal antigen pneumolysin (PLY)
because PLY facilitates bacterial invasion. We measured serum anti-PLY
antibodies in two separate populations of HIV- infected and
HIV-seronegative controls, using both an enzyme-linked immunosorbent assay
method and a functional assay of antibody inhibition of PLY-induced
hemolysis and cytotoxicity. HIV-infected patients in the United States had
significantly lower titers of anti- PLY antibodies by both methods than did
seronegative control subjects. Moreover, HIV-infected patients in Kenya who
later developed pneumococcal bacteremia also had significantly lower
anti-PLY antibody levels at baseline compared with seronegative control
subjects. We conclude that lower baseline levels of antibodies to PLY are
associated with the higher incidence of bacteremic pneumococcal infections
among HIV-infected patients.
