Influence of tubercle aggregate size on severity of adjuvant arthritis in the rat.

Incorporation into Freund's complete adjuvant of tuberculous aggregates smaller than 90 mum in size is essential to produce adjuvant arthritis in the rat, and this correlates with a significantly greater degree of cell-mediated immunity to tuberculous antigens produced by small aggregates (smaller than 90 mum), when compared with large (larger than 90 mum) aggregates. This requirement for small aggregates to render Freund's complete adjuvant arthritogenic is not paralleled by detectable differences in antimycobacterial humoral antibody production nor by a size-dependent requirement for a conventional adjuvant effect.