The present study was undertaken to examine the ultrastructure of the
lymphocytes of patients with relapsing-remitting multiple sclerosis (R
RMS) and to compare it to that of the lymphocytes of multiple sclerosi
s (MS) patients treated with intravenously administered immunoglobulin
0.4 mg/kg of body weight for 5 consecutive days followed by booster d
oses of immunoglobulin 0.4 mg/kg every two months for a total of 12 mo
nths. Peripheral blood lymphocytes of healthy volunteers served as con
trol. The results indicate that lymphocytes of untreated patients diff
er markedly by both ultrastructure, as well as the number and size of
their mitochondria. Since most of these changes disappeared following
treatment, it is suggested that they are an expression of lymphocyte a
ctivation in this disease.