Two small lymphocyte subpopulations in human peripheral blood. II. Functional characterization in vitro

Two small lymphocyte subpopulations from human peripheral blood were produced by rosette sedimentation procedures, and tested for in vitro functions by stimulation with mitogens, PPD and allogeneic lymphocytes, and for effector capacities in ADCC. The non-T, non-Fc subpopulation had previously been found to be a SmIg+ fraction which did not aquire new surface markers during unstimulated culture, did not respond to mitogens, PPD or allogeneic cells but were potent MLC stimulators. In addition, they were poor ADCC effector cells. The non-T, non-B ('Null') cells, which showed varying surface marker profiles from donor to donor, were able to respond to mitogens and PPD, but were weak MLC responders. Potent ADCC effector capacity was, however, found to be exhibited by this subpopulation.

An improved technique for obtaining E rosettes with human lymphocytes and its use for B cell purification

The standard E rosette method and two previously described methods claimed to give improved E rosetting for enumeration of human T lymphocytes have been compared with respect to the speed of rosette formation, and the mechanical stability of the rosettes formed. Following rosette formation with the three methods, the lymphocyte-erythrocyte suspensions were sedimented on Ficoll-Isopaque to deplete them of rosette-forming cells and red cells. The purified lymphocyte preparations were tested for B and T cell markers to determine the degree of contamination with T cells. One of the improved rosetting methods was clearly better than the others, and led to the recovery of B lymphocytes with a contamination of only 2.0+/-1.9 per cent of T lymphocytes.