Impairment of natural killer cell activity in Chlamydia trachomatis infected individuals

Abstract

SummaryNatural killer (NK) cell activity is impaired in Chlamydia trachomatis-infected patients. The mechanisms behind the altered NK functions are not clear, but data concerning NK and antibody-dependent cellular cytotoxicity (ADCC) activity have been reported. To investigate whether this impairment is related to a defect at the target cell binding and/or the postbinding level, we evaluated highly purified NK cells obtained from 125 C. trachomatis-infected patients and compared them with 101 normal controls for their ability to kill K-562 and U-937 cell lines using a 51 Cr release assay; release tumour necrosis factor-alpha (TNF-␣) and interferon-gamma (IFN-␥); and kill anti-IgM preincubated P-815 cell line (ADCC activity). We found a decrease in the lytic capability of NK cells from C. trachomatis-infected patients against target cell lines; decreased ability to kill bound target cells; and low levels of released TNF-␣ and INF-␥ after incubation with U-937 cells. Taken together, these findings suggest that the impaired NK cell reaction during chlamydial infection is related to defects both at the target and postbinding levels. However, the precise mechanisms remain to be determined. The inability to restore normal NK activity after long-term culture in the presence of high levels of recombinant IL-2 support the hypothesis of an anergic process during chlamydial infection.

Stimulated peripheral blood mononuclear cells from chlamydia-infected women release predominantly Th1-polarizing cytokines

“…This hypothesis is further supported by a prior study demonstrating that Ct EB-stimulated PBMCs had high levels of IFN-γ production by NK cells [13]. Interestingly, another study demonstrated that NK cell function (including IFN-γ production) was impaired in some Ct-infected humans [14]. Together, these findings suggest that NK cells may contribute to IFN-γ production in some, but not all, Ct-infected individuals and warrants further investigation.…”

NK cell compartment in patients with coronary heart disease

“…Moreover, cytotoxic activity of these cells may be modulated during infections by both bacteria and viruses [19-21]. Also inflammation affects NK cell functions; our previous studies showed that high concentration of proinflammatory cytokines correlates with low NK cytotoxic activity [22,23].…”

NK Cells Promote Type 1 T Cell Immunity through Modulating the Function of Dendritic Cells during Intracellular Bacterial Infection

“…The important role of NK cells in host defense to infection has been demonstrated in several infection models including viral and intracellular bacterial infections (7)(8)(9). Limited studies have reported inconsistent findings on the role of NK cells in host immune response to chlamydial infections especially with different model systems (10)(11)(12)(13)(14)(15). In murine genital tract chlamydial infection, NK cells are found to be potent producers of IFN-g at the early stages of infection; NK cells are recruited into genital epithelium at early time points and may recognize/lyse infected cells (10).…”

“…However, in the studies using lung infection models and genetically modified animals, it was found that the role of NK cells in host defense against chlamydial infection was negligible (12,14,15). Even in the studies showing a protective role of NK cells in host defense against chlamydial infection (10)(11)(12), the mechanism(s) remains largely unclear.…”