Chlamydia pneumoniae enhances CD4+ and CD8 +T effector memory cell IL-2 and IL-4 responses in stimulated peripheral blood mononuclear cells in human subjects
Sunday, March 4, 2018
South Hall A2 (Convention Center)
Yitzchok M Norowitz, B.S., Stephan Kohlhoff, Natalie Banniettis, Margaret R Hammerschlag, Tamar A. Smith-Norowitz, PhD
RATIONALE: Chlamydia pneumoniae causes respiratory infection in adults and children. Previous studies in our laboratory identified significantly higher in vitro T lymphocyte responses to C. pneumoniae in children with asthma compared to healthy controls which may indicate the presence of T effector memory (TEM) lymphocytes. In the present study we screened healthy subjects for the presence of TEM cells and their cytokines. CCR7 negative effector TEMs may indicate persistent infection with C. pneumoniae.

METHODS: Peripheral blood mononuclear cells (PBMC) (1×106/mL) from adult healthy subjects were infected or mock-infected for 1h +/- C. pneumoniae TW-183 at a multiplicity of infection (MOI) =1.0, 0.1 or 0.01 and cultured for 24-48 hrs. Distributions of lymphocytes (CD4+, CD8+) and TEM cells (CD4+CD45 RA+, CD4+CD45 RO+, CD4+CCR7+/-; CD8+CD45RA+, CD8+45RO+, CD8+CCR7+/-) were determined. Levels of intracellular Interleukin (IL)-2, IL-4, and Interferon (IFN)-gamma were measured (flow microfluorimetry).

RESULTS: C. pneumoniae infection (48 hr) led to an increase (~90%, 43%, respectively) in numbers of TEMS (CD4+IL-2+, CD4+ IL-4+) (CD8+IL-2+, CD8+ IL-4+); however, numbers of TEMS (CD4+ IFN-gamma+, CD8+IFN-gamma+) did not change significantly (P<0.05).

CONCLUSIONS: C. pneumoniae infection can enhance CD4+ IL-2+, CD4+IL-4+, CD8+IL-2+ and CD8+IL-4+ TEM responses in healthy subjects. These findings are important in understanding the persistence of C. pneumoniae infection and may allow development of diagnostic tests.