Background/Purpose:
To determine the efficacy of pneumococcal polysaccharide vaccine (PPV-23) in
patients on mycophenolate mofetil
(MMF) therapy and compare efficacy to other DMARDS.

Methods:   In a pilot study,
we evaluated 20 patients immunized with PPV-23. The MMF study group included 10
patients (8 SLE, 1 uveitis and 1 dermatomyositis).  The control group also included 10 patients
(4 RA, 3 SLE, 1 PsA, 1 uveitis)
treated with methotrexate, hydroxychloroquine
or etanercept. 
Both groups were similar regarding average age, (put in ages of both
groups) gender (put in % female of the both groups) and prednisone use (put in
% prednisone use of both groups). Serum samples for 14 pneumococcal serotypes
were collected pre-immunization and eight weeks post-immunization.  Serum IgG titers
were analyzed using ELISA.  We calculated
the stimulation index (SI) of 14 serotypes by dividing the post-immunization
titer by the pre-immunization titer to determine vaccination efficacy.  Based on the American Academy of Allergy,
Asthma and Immunology (AAAAI) definition of protective titers, the primary endpoints of the study were either a ≥ 2-fold, >
3-fold or > 4-fold increase in post-immunization antibody titers and ≥
1.3ug/ml antibody concentration in at least 70% of the 14 pneumococcal
serotypes.

Results: Humoral responses to PPV23 in
patients treated with MMF were significantly lower compared to the control
group.  Suppressed antibody responses
were observed in the MMF group as defined by a lack of 4-fold (p = 0.0001),
3-fold (p = 0.001), and 2-fold (p = 0.0163) increase in the SI vs the control group. 
Twenty percent of patients receiving MMF (n=3) and fifty percent of
patients (n=8) in the control group had a  ≥ 2-fold increase in
post-immunization antibody titers to 10 of the 14 serotypes.  Forty percent of patients in the MMF group
had protective antibody levels (> 1.3 ug/ml) as
compared to sixty percent on other DMARDS (8.29 + 2.79 vs
9.22 + 4.84, p = 0.51). Statistical significant differences were also observed
in serotypes 51 and 4 (p = 0.05 and p = 0.025 respectively) between MMF and the
control group.

Conclusion: To our knowledge, this is the first investigation
of the efficacy of pneumococcal polysaccharide vaccine (PPV-23) in patients
taking MMF for SLE and other autoimmune diseases.  In this pilot study, humoral
responses following pneumococcal vaccination in patients receiving MMF were
suppressed and lower than in patients on other DMARDS.  The recommendation for pneumococcal
immunization prior to MMF initiation is therefore supported.