Plasmodium vivax : paroxysm-associated lipids mediate leukocyte aggregation

Table 1 Effect of plasma samples, cytokines and parasite products in the white blood cell aggregation assay

Expt. No.	Sample	% RCAI (Median)	25%	75%
1	NHP	5.80	1.6	7.3
2	PP	100	100.0	100.0
3	POPP	20.90	5.6	28.4
4	NHP+cytokines	17.20	6.7	23.5
5	NHP+PvAg	18.60	4.5	20.8
6	NHP+PvAg+ cytokines	88.50	79.8	92.4
7	NHP+RBC Ag+ cytokines	10.00	2.4	12.9
8	POPP+cytokines	18.30	7.5	22.3
9	POPP+PvAg	16.40	9.4	18.1
10	POPP+PvAg+ cytokines	77.10	64.7	79.8
11	NHP+LPS	6.10	1.9	7.2
12	NHP+LPS+cytokines	16.10	6.9	18.6
13	PP + IRS-Pv	24.90	15.6	28.4
14	PP + IRS-Pf	54.40	48.6	65.4
15	PP + CHS	17.00	14.2	19.5

% RCAI: % Relative Cell Aggregation Index
25%–75%: 25th and 75th percentiles
Normal human plasmas (NHP) and post paroxysm plasmas (POPP) were reconstituted with freeze-thawed extracts of P. vivax schizonts (Pv Ag), normal red cell extracts (RBC Ag), recombinant human cytokines TNF-∝, GM-CSF, IL-6 and IL-10 (cytokines) or E. coli lipopolysaccharide (LPS). P. vivax paroxysm plasma (PP) was pre-incubated with rabbit serum raised against P. vivax schizonts (IRS-Pv), with rabbit serum raised against P. falciparum schizonts (IRS-Pf) or with convalescent human serum (CHS) collected 4 – 6 weeks after drug cure of a P. vivax infection, from semi-immune individuals resident in a malaria-endemic area prior to being tested in the cell aggregation assay. The table provides the median values together with the interquartile range (25%–75%).