ABSTRACT
Becaose of immunologica deficiency in the serum, patients with sickle cell anaemia [SCa] are especially susceptible to repeated pneumococcal infections and sepsis This study was done on sera from 12 homozygous sicklers who were not suffering from infection or crisis at time of study The sickle sera were compared individually with normal pooled serum from ten donors used as a control throughout this work. Both serum sources were used for opsonization of Streptococcus pneumoniae type 2 for their ingestion by human neutrophils, also for measuring the immunological deposition of C3 complement on the surface of the pneumococci Using the immunofluorescent anti C3 revealed no quantitative difference between the two serum groups in the amount of C3 deposited on the surface of the bacteria. However, the sickle sera mounted less opsonic function Than the pooled serum. This was through less ingestion ofpneumococci by human neutrophils when the sickle serum was used as a source of opsonization