Table 2.

Frequency of Naturally Acquired Immune Responses to Plasmodium falciparum Merozoite Surface Protein 1 (MSP1) in Adults and Children

Assay, Variable	Adults Aged ≥18 y	Children Aged 1–14 y	Pa	Children Aged 10–14 y	Children Aged 5–9 y	Children Aged 1–4 y
IFN-γ ELISA
Subjects, no.	90	88		22	44	22
Stimulus, %
PHA	100.0	98.0	.500	100	95	100
M2 peptide	30.7	13.6	.007	13.4	18.2	12.5
MSP142 3D7	62.5	34.1	.001	45.4	27.3	36.4
MSP142 FVO	47.7	26.1	.003	36.4	25.0	18.2
IFN-γ ELISPOT
Subjects, no.	94	91		19	46	26
Stimulus, %
PHA	95.0	91.0	.447	86.4	93.9	89.7
M2 peptide	9.5	4.4	.152	5.3	3.8	7.7
MSP142 3D7	37.9	26.4	.126	21.1	21.7	38.5
MSP142 FVO	9.5	2.2	.036	0.0	2.2	3.8
IL-10 ELISA
Subjects, no.	90	88		22	44	22
Stimulus, %
PHA	100.0	100.0	NS	100.0	100.0	100.0
MSP142 3D7	59.1	44.6	.058	42.9	42.9	55.0
MSP142 FVO	21.6	16.9	.434	4.8	16.7	30.0
IgG antibody ELISA
Subjects, no.	90	88		22	44	22
Stimulus, %
MSP142 3D7	49.5	25.0	.003	22.7	28.6	20.7
MSP142 FVO	36.6	28.0	.190	22.7	34.7	20.7

Bold values denote significant results.

Abbreviations: ELISA, enzyme-linked immunosorbent assay; IFN-γ, interferon γ; IgG, immunoglobulin G; IL-10, interleukin 10; MSP1₄₂, 42-kD C-terminal fragment of Plasmodium falciparum MSP1; NS, not significant.

^a Adults vs children.