Leucocyte migration inhibitory activity in supernatants of cultured human mono-nuclear cells stimulated with mitogens or C3- and Fc-receptor reactions.

We studied whether reactions at the lymphocyte membrane receptors for complement, immunoglobulin or mitogens would induce lymphokine production. Human peripheral blood mono-nuclear cells were stimulated by C3- or Fc-receptor reactions and with phytohaemagglutinin (PHA) or lipopolysaccharide (LPS) and cultured for 3 or 4 days. C3- and Fc-receptor reactions were brought about by rosette formation with red cells coated with human complement or antibody. Culture supernatants were assayed for migration inhibitory activity with human leucocytes by the leucocyte-migration-in-agarose test. On the average, no migration inhibitory activity could be detected in cultures stimulated by C3- or Fc-rosette formation, mean migration indices (MI) being 99-2 and 96-1, respectively. Of the mitogens, PHA induced distinct lymphokine synthesis (mean MI 60-2) while the mean MI with LPS varied from 97-9-69-8, depending on the mitogen preparation used and the conditions of culture. We conclude that PHA and LPS are able to activate human lymphocytes into elaboration of migration inhibitory factors whilst reactions at C3- or Fc-receptors fail to do so.