Shear Stress Effects on Human T Cell Function

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Abstract
A modified Couette viscometer was used to study the effect of shear stresses on human T lymphocyte functions. Cell suspensions containing T cells, B cells, and monocytes were subjected to uniform shear stresses of 100 and 200 dynes/cm2 for 10 minutes. After stress exposure, the T cell response to the lectin phytohemagglutinin‐P (PHA‐P) was a strong function of the total cell concentration in culture. Stressed cells cultured with 0.5 μg/ml PHA‐P at an initial concentration of 1 × 106 cells/ml did not incorporate significant amounts of tritium‐labelled thymidine into their DNA. This inability to incorporate thymidine could be related to insignificant amounts of interleukin‐2 (IL2) detected in cell culture supernatants. A size analysis revealed that exposure to stress interfered with the ability of PHA‐P to induce cellular enlargement characteristic of an activation response. Fluorescence flow cytometric studies showed that the membrane depolarization response of cell suspensions to PHA‐P was significantly affected after exposure to shear stresses. In contrast, when shear stressed cells were cultured at lower cell densities of 0.5 × 106 and 0.25 × 106 cells/ml, the functional responses to PHA‐P were similar to those of controls. The data obtained suggest that controlled exposure to sublytic shear stresses results in alterations that can affect the proliferative response of the T cell population, and that these alterations are cell‐density dependent.