Effect of a proline-rich polypeptide (PRP) on the development of hemolytic anemia and survival of New Zealand black (NZB) mice.

PRP, administered intraperitoneally into NZB mice, twice a week, at doses 0.01-1 microgram per mouse, significantly lowered the incidence of positive Coombs' reaction and prolonged the mean age of the mice. The effect of PRP on survival of mice was better when the treatment with PRP started early (in mice showing first signs of the disease). The results suggest that PRP may induce, from a precursor pool of cells, suppressor cells controlling development of the disease. In addition, the data indicate that PRP may have a therapeutical value in treatment of autoimmune disorders, e.g. the juvenile arthritis.