Characteristic and functional specificity of anti-human BAT (brain associated thymocyte antigen) serum.

A rabbit antiserum to human fetal brain after multiple absorption reacted with 100% of thymocytes, 55% of peripheral blood lymphocytes and 90% of enriched T lymphocytes, but not significantly with B lymphocytes. Spontaneous SRBC rosette formation was inhibited by anti-BAT pretreatment, but EAC-rosette formation remained unaffected. The antiserum was itself highly stimulatory. However, cells treated with the antiserum and complement exhibited marked inhibition of responsiveness to Con A, little effect with PHA and no alteration with PWM. The MLC reaction was inhibited only when the responder cells were treated with the antiserum and complement. Treatment of sensitized lymphocytes with the antiserum and complement caused a dose-dependent suppression of blastogenic response to both PPD and n-DNA. No effect, however, was noted in MIF producing cells. Con A induced suppressor function of lymphocytes was abolished by treatment with the antiserum and complement. These results indicate that the anti-BAT serum obtained by us can be utilized for the isolation of T lymphocyte subsets.