INFLAMMATORY CYTOKINES IN NORMAL HUMAN TEARS

Purpose. To elucidate inflammatory cytokine levels in normal human tea rs, we investigated the concentrations of interleukin-1 alpha (IL-1 al pha), interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), and interl eukin-8 (IL-8) both in basal tears and reflex tears of normal healthy eyes. Methods. Tear samples were collected from 270 healthy, normal vo lunteers with no past history of ocular surface disease; the total num ber of eyes was 295. All tear samples were collected in graduated disp osable microcapillaries from the conjunctival cul-de-sac. Reflex tear stimulation was carried out by inserting an applicator into each volun teer's nose. Cytokine levels in basal tears and reflex tears were dete rmined by ELISA. Tears were not diluted, and pooled samples were used for the cytokine assays. Results. In basal tears, the concentrations o f lL-1 alpha, -1 beta, -6 and -8 were 10.9 +/- 1.2, 12.9 +/- 2.3, 226. 2 +/- 29.6 and 731.4 +/- 116.2 pg/ml, respectively. In reflex tears, I L-1 beta was not detectable, and the concentrations of IL-1 alpha, -6 and -8 were 9.3 +/- 2.7, 11.6 +/- 1.6 and 276.1 +/- 47.5 pg/ml respect ively. IL-1 beta, -6 and -8 levels in reflex tears were significantly lower than those in basal tears, except for IL-1 alpha. Conclusions. I n the present study, the normal concentration range of inflammatory cy tokines in human basal tears was clarified, as a baseline for further studies to examine the levels of these cytokines in tears during disea se states.