TABLE 1.

Binding of nonspecific human IgM to CSA-selected parasites^a

Parasite isolate	Origin	Selected for CSA binding	Recognized by female but not male antibodies	% of iRBC binding IgM
SD2H3	Sudan	No	No	1
SD2H3CSA		Yes	Yes	74
SD202	Sudan	No	No	4
SD202CSA		Yes	Yes	94
Busua	Ghana	No	No	9
BusuaCSA		Yes	Yes	91
Gb337	Gabon	No	No	2
Gb337CSA		Yes	Yes	79
HB3	Honduras	No	No	4
HB3CSA		Yes	No	47
FCR3	Gambia	No	No	4
FCR3CSA		Yes	Yes	88

^aResults are given as the percentage of IgM-positive iRBC observed in a representative experiment on each line. All lines were tested at least three times, some as many as 10 times. Consistent results were obtained in all experiments. There was variation in the time at which each culture reached sufficient density to allow testing and also in the rate at which different lines lost their selected adhesion property (27). This precluded averaging results, because the timing of each test postselection will not be strictly comparable.