Comparative in vitro sensitivities of human immune cell lines, vaginal and cervical epithelial cell lines, and primary cells to candidate microbicides nonoxynol 9, C31G, and sodium dodecyl sulfate

Abstract

In experiments to assess the in vitro impact of the candidate microbicides nonoxynol 9 (N-9), C31G, and sodium dodecyl sulfate (SDS) on human immune and epithelial cell viability, cell lines and primary cell populations of lymphocytic and monocytic origin were generally shown to be equally sensitive to exposures ranging from 10 min to 48 h. However, U-937 cells were more sensitive to N-9 and C31G after 48 h than were primary monocyte-derived macrophages. Cytokine activation of monocytes and lymphocytes had no effect on cell viability following exposure to these microbicidal compounds. Primary and passaged vaginal epithelial cultures and cell lines differed in sensitivity to N-9 and C31G but not SDS. These studies provide a foundation for in vitro experiments in which cell lines of human immune and epithelial origin can be used as suitable surrogates for primary cells to further investigate the effects of microbicides on cell metabolism, membrane composition, and integrity and the effects of cell type, proliferation, and differentiation on microbicide sensitivity.

FIG. 1.

SupT1 cells are more sensitive to C31G than to N-9 or to SDS. SupT1 cells were exposed to N-9, C31G, or SDS for 10 min (A), 2 h (B), 8 h (C), or 48 h (D) and were assayed for viability immediately after the exposure period. In experiments represented by this and subsequent figures, cell viability after exposure, determined by MTT assay, is expressed relative to that of mock-exposed cells. Unless otherwise indicated, each graph illustrates data collected in two independent experiments in which each concentration was examined in triplicate wells. Error bars indicate standard deviations on mean data.

FIG. 2.

Primary human T lymphocytes are similar to cell lines in sensitivity to N-9, C31G, or SDS. Primary human T lymphocytes were exposed to N-9, C31G, or SDS for 10 min (A), 2 h (B), 8 h (C), or 48 h (D) and subsequently assayed for viability as described.

FIG. 3.

U-937 cells are more sensitive to C31G than to N-9 or to SDS. U-937 cells were exposed to N-9, C31G, or SDS for 10 min (A), 2 h (B), 8 h (C), or 48 h (D) and subsequently assayed for viability.

FIG. 4.

Primary human MDMs are similar to a monocytic cell line in sensitivity to N-9, C31G, or SDS. Primary human MDMs were exposed to N-9, C31G, or SDS for 10 min (A), 2 h (B), 8 h (C), or 48 h (D) and subsequently assayed for viability.

FIG. 5.

Stimulation of immune cell lines does not appreciably change their sensitivity to N-9, C31G, or SDS. SupT1 cells stimulated with PHA (2.5 μg/ml) and interleukin 2 (20 U/ml) for 24 h were exposed to N-9, C31G, or SDS for 10 min (A) or 48 h (B) and were subsequently assayed for viability as described. Similarly, U-937 cells were treated with GM-CSF (40 U/ml) and M-CSF (100 U/ml) for 24 h and were exposed to N-9, C31G, or SDS for 10 min (C) or 48 h (D).

FIG. 6.

Primary and tertiary HVK cultures differ from continuous human vaginal cells in their sensitivity to N-9 or to C31G. Primary HVKs (a single, representative experiment) (A), tertiary HVKs (passed twice after isolation) (B), immortalized VK2/E6E7 human vaginal epithelial cells (C), and HeLa cells (D) were exposed to N-9, C31G, or SDS for 48 h and subsequently assessed for viability.