Interferon-gamma responses to Plasmodium falciparum liver-stage antigen-1 and merozoite-surface protein-1 increase with age in children in a malaria holoendemic area of western Kenya

Table 2 Frequencies and geometric mean levels of IFN-γ responses to PHA, LSA-1 and MSP-1 peptides by presence of P. falciparum parasitemia

Condition	PHA		MSP-1 (aa 20–39)		LSA-1, T3
Blood smear	No. pos./Tot. (%)^a	Geo. mean (range)^b	No. pos./Tot (%)	Geo. mean (range)	No. pos./Tot (%)	Geo. mean (range)
P. falciparum positive	36/36 (100)	2545.4 (164.8–6891.6)	7/32 (21.9)	145.8 (0–1245.9)	7/31 (22.6)	105.4 (0–254.3)
P. falciparum negative	12/12 (100)	1908 (231.1–4254.1)	2/9 (22.2)	28.4 (0–150.3)	2/8 (25.0)	39.0 (0–983.5)
P	NS^c	NS^d	NS	NS	NS	NS

^a A positive response was defined as any response ≥ 20 pg/ml above that of unstimulated cell culture supernatants and had a positive or negative blood smear. ^b Geometric mean cytokine levels in pg/ml. ^c NS = not significant. P < 0.05 considered significant, as determined by χ² test for trend across age groups. ^d P < 0.05 was considered significant as determined by analysis of variance of log-transformed values across age groups.

ISSN: 1475-2875