Both primary and secondary responses to sheep erythrocytes and to Brucella abortus antigen have been obtained in cultures of dispersed rabbit spleen cells. Removal of adherent cells by repeated incubation of spleen cells on absorbent cotton diminished the ability of the spleen cell suspensions to give secondary as well as primary responses in vitro.
When comparing cultures made in dishes and in tubes, the loss of responsiveness after incubation on cotton was much more evident in the dish cultures. It was concluded that the cell-to-cell interaction needed for immune responses to particulate antigens in vitro was more readily interfered with when the cells were spread over a larger surface area.
The proliferative response to antigen, as measured by uptake of 3H-thymidine in tube cultures of the sensitive spleen cells, appeared particularly resistant to the depletion effect of adherent cell removal.
Dispersed spleen cells from sensitized mice gave a secondary response to sheep erythrocytes. This response was readily abolished by one incubation on absorbent cotton when the cells were cultured in dishes.