SERUM ANTIBODY-TITERS TO SHIGELLA LIPOPOLYSACCHARIDES AND INVASION PLASMID ANTIGENS IN HEALTHY COSTA-RICAN AND SWEDISH WOMEN

Specific serum antibody titres to defined lipopolysaccharides (LPS) of Shigella spp. and Salmonella serogroup B (BO) and Shigella invasion p lasmid antigens (Ipa) were determined by enzyme immunoassays in health y Costa Rican women from low (n = 34), middle (n = 36) and high (n = 1 9) socioeconomic conditions and from 64 Swedish women. Specific Ige an tibody titres were the highest, in particular to the S. flexneri Y LPS , with mean titres of 750 (SD = 360), 690 (380), and 820 (300) for the Low, Middle and High Costa Rican groups respectively. Lower titres we re recorded against S. sonnei and S. dysenteriae type 1. Titres agains t Salmonella LPS were very low ( < 250). In Swedish women, significant ly lower serum anti-LPS titres were found (p < 0.05). No statistically significant differences regarding socioeconomic conditions or serum a nti-LPS titres were seen in the Costa Rican groups (p > 0.05). Mean Ig G-titres to the Ipa of 330 (150), 220 (170) and 140 (110) were found f or the 3 Costs Rican groups, respectively. The IgG and Ig M titres to Ipa in serum from the Low group were significantly higher than those o f the High group (p < 0.05). The mean serum IgG titre of 70 (90) for t he Swedish women was significantly lower than that of the Low and Midd le groups (p < 0.05), but similar to that of the nigh group (p > 0.05) . High IgC anti-Ipa titres were found in 38% from the Low, 19% from th e Middle but none in the High group (mean value of the High group +2 S D). The anti-Ipa antibodies in the Costs Rican groups seemed to be a b etter indicator of Shigella exposure than were anti-LPS antibodies. A good degree of correlation was found between serum and colostrum IgA a nti-Ipa titres (0.651, p < 0.001), and serum S. flexneri LPS and colos trum IgA anti-S. flexneri LPS antibody titres (0.607, p < 0.001).