Smooth muscle autoantibodies in normal rabbit sera. Cross-reaction with human platelets as demonstrated by immunofluorescence.

27 normal rabbit sera were tested by indirect immunofluorescent technique. All sera stained smooth and skeletal muscle of human and mammalian tissues and human washed platelets. Two sera had ANA activity. These autoantibodies had low titres. Lysed but not intact platelets neutralized the rabbit SMA sera activity.