ABSTRACT Background: Systemic Lupus Erythematosus (SLE) is a chronic autoimmune disease which is characterized by B-cell abnormality and auto-antibody generation. Since bacterial infections are the most important causes of mortality in these patients, pneumococcal vaccination is recommended for children with SLE. Objective: To investigate humoral immunity and specific-antibody formation in response to a 23-valent polysaccharide pneumococcal vaccination in SLE children and asthmatic control group. Method: The case and control groups consisted of 30 children with the mean age of 13 years who were matched by sex and age. Anti-pneumococcal antibody titers were determined using Enzyme-Linked Immunosorbent Assay (ELISA) before the vaccination with the 23-valent pneumococcal vaccine and 3 weeks later in both groups. Also the correlation between anti-pneumococcal antibody titer and different factors including age, sex, lupus activity, disease duration, medications, history of recurrent infections, and laboratory data were investigated. Results: Both groups showed significant increases in anti-pneumococcal antibody level after vaccination (p≤0.001). The increase in antibody level were almost the same in both groups (p≥0.05) such that 77.7% of SLE children and 86.2% of control children showed at least 2-fold increase in anti-pneumococcal antibody titer following immunization. Significant correlations were seen between the level of post-immunization anti-pneumococcal antibody with the age of children with SLE (p=0.02) and their age of disease onset (p=0.02). Conclusion: It is concluded that pneumococcal vaccination is generally immunogenic in children with SLE. However, a small group of patients show impaired response to the vaccine
