A microculture system for generating haemolytic antibody responses from human tonsillar lymphocytes

Small numbers of Ficoll-Hypaque purified human tonsillar lymphocytes were stimulated with PWM to produce SRBC-specific PFC in a microculture system. The magnitude of the response varied among different tonsils but was typically between 200 and 1000 PFC/10(6) cells cultured. Little or no response was observed in the absence of PWM. SRBC failed to stimulate a SRBC-specific response and the presence of this antigen in PWM-stimulated cultures depressed the response. The time of the maximum response was inversely related to the number of cells cultured. In addition, the duration of the response was limited by rapid depletion of critical medium requirements and/or build up of inhibitory factors especially when the cell concentration exceeded 5 x 10(5) cells/culture. This effect could be partially overcome by daily feeding of cultures with fresh medium. Fractionation studies indicated a requirement for both T and B cell populations. Constant efficiency of PFC production with respect to cell number could be achieved by the addition of inactivated autologous 'filler' cells. The significance of these results and applicability of the microculture system to a detailed analysis of human antibody responses will be discussed.