The effect of transfer factor on spontaneous shedding of sheep red blood cell binding receptors of T lymphocytes in vitro.

Many effects of transfer factor can be used for testing of its activity in vitro. Its effect on rosette formation has been utilized in two methods: the enhancement of rosetting of trypsin-treated T lymphocytes and the increase of 'active' rosettes depressed under some immunopathological conditions. 'Active' rosetting lymphocytes of healthy blood donors if kept at 37 degrees C for 4 hr shed partly their sheep red blood cell-binding receptors into the culture medium supplemented with 25% fetal calf serum. The adding of the negative skin test-converting fraction of dialysable leucocyte extracts inhibits the decrease of the number of rosettes. Possible explanations for the observed phenomenon are: transfer factor increases the rate of receptor synthesis, it causes uncovering or redistribution of the receptors, or it stabilizes otherwise shed membrane structures.