Influence of middle-molecular-weight solutes from dialysate on the migration rate of leukocytes.

To investigate further the biologic activity of solutes in the middle-molecular-weight range, we studied the influence of these compounds on the migration of unseparated white blood cells and separated granulocytes and lymphocytes. Middle molecules (MM) inhibit the migration of unseparated leukocytes, but this effect on lymphocytes was seldom observed. With scanning electron microscopy, unseparated leukocytes were shown to adhere to one another, forming cellular clumps. This phenomenon could not be seen when separated cells were used. These results give some insight into the mechanism of inhibition exerted by MM and into the changes, observed in earlier experiments, of cellular composition of skin exudate obtained from untreated patients with uremia.