Evaluation of antibody responses to pneumococcal vaccines with ELISA and opsonophagocytic assay

Antibodies to a capsular polysaccharide (PS) provide protection against Streptococcus pneumoniae which express the homologous capsular serotype, and pneumococcal vaccines are designed to induce antibodies in the capsular PS. Levels and opsonophagocytic capacity of antibodies to the capsular PS of S. pneumoniae serotype 19F were determined by sera from adults immunized with 23-valent S. pneumoniae capsular PS vaccines. Geometric means of IgG anti-19F antibody level and specific opsonic titer rise significantly after immunization. The level of anticapsular PS antibodies for S. pneumoniae 19F serotype is fairly well correlated (r2=O.63) with the opsonophagocytic activities of sera. However, 3.7% (1/27) of serum samples display strikingly less opsonophagocytic activity than expected on the basis of their antibody level. Thus, antibody level may be of general use in predicting vaccine-induced protection among adults for 19F serotype. However, the opsonic activity data suggest that antibody levels are not always indicative of functional antibody.

Serum sialic acid and glycosaminoglycans in patients with rheumatoid arthritis

Serum levels of sialic acid [SA], serum glycosaminoglycans [GAGs] and urinary excretion of glycosaminoglycans were analyzed in 76 patients suffering from rheumatoid arthritis [RA]. The values were compared with those of 69 normal healthy controls. Other related parameters of disease activity were also analyzed, i.e, serum rheumatoid factor [RF], C-reactive protein [C-RF], ceruloplasmin [CF],hemoglobin [Hb] and erythrocyte sedimentation rate [ESR]. There was a significant elevation in the serum SA and urinary GAGs levels of the RS patients compared to control subjects, while no such elevations in serum GAGs were noticed. Serum SA levels were significantly correlated with disease activity. This suggests that serum SA levels can be used as an additional parameter to assess disease activity in RA patients