ABO blood groups and isoagglutinins in systemic lupus erythematosus.

In 45 patients with SLE the frequency of groups B and AB exceeded that of the controls, the difference reaching the double of the standard error. The isoagglutinin titers were quite similar in the two series. There was no association of the disease with the frequency of the secretor type nor with the quantity of group substances or isoagglutinins present in saliva and urine. The isoagglutinin titers in the sera of non-secretors were low.