The kinetics of rosette-forming cell response against sheep erythrocytes in the lizard.

The immune response of the lizard Calotes versicolor to sheep erythrocytes (SRBC) has been studied in terms of the appearance of rosette-forming cells (RFC) and plaque-forming cells (PFC). Two distinct RFC peaks were observed in the spleen, one within three days and the other, between six and ten days after immunization with 0.1 ml of 2.5%, 0.25% or 0.025% SRBC. Lower doses of antigen induced greater and quicker first RFC peaks, whereas higher doses stimulated increasing numbers of PFC as well as quicker appearance of second RFC peak. The early increase in RFC response is suggested to be due to "helper" activity and the second peak to the proliferation of precursors of antibody producing cells. Formalinised SRBC induced the formation of the first RFC peak but not the second, thus supporting the above suggestion. The interesting possibilities with regard to the dissociation of various cellular events during the development of antibody response in the lizard immune system are discussed.