TABLE 2.

Cytosolic-free-calcium peak increase (Δ[Ca²⁺]_i) induced on THP-1 cells stimulated with cell-free PBS-20 mM HEPES conditioned for 2 h by the addition of A. castellanii trophozoites (6 × 10⁶/ml) (iPBS) or with its fractions^a

Sample	Mean Δ[Ca2+]i (nM) ± SE
iPBS	158.36 ± 12.50*
pPBS (amoebic metabolites, >30 kDa)	2.66 ± 1.23§
rPBS (amoebic metabolites, 10-30 kDa)	4.80 ± 1.98§
sPBS (amoebic metabolites, <10 kDa)	172.28 ± 8.24**
mPBS (amoebic metabolites, >10 kDa, heat inactivated)	2.54 ± 1.52§

^aCell stimulation was obtained with 80 μl of the samples indicated. Values are means ± the standard error of at least three experiments. ∗, P < 0.05 versus the control; ∗∗, P < 0.01 versus the control; §, not significant. The basal value of the [Ca²⁺]_i in THP-1 cells is 133.55 ± 3.58 nM (n = 45).