The Effect of the Amount of Mycobacterial Adjuvants on the Immune Response of Strain 2, Strain 13 and Hartley Strain Guinea Pigs to DNP-PLL and DNP-GL

The effect of the concentration of mycobacterial adjuvants on the immune response of strain 2, strain 13 and Hartley guinea pigs to DNP-PLL and DNP-GL was investigated. The ability to respond to these antigens in guinea pigs is controlled by a dominant autosomal gene. A small number of non-responder strain 13 animals or Hartley non-responder animals produced low serum levels of anti-DNP antibodies following prolonged immunization with DNP-PLL and 0.5 mg/ml Mycobacterium butyricum. These antibodies were detected by a modified Farr technique using high specific activity 3H DNP-EACA. However, none of the non-responder guinea pigs similarly immunized with DNP-GL produced detectable antibodies. When the amount of mycobacteria in the adjuvant was increased to 10 mg/ml Mycobacterium tuberculosis, all non-responder animals immunized with DNP-PLL produced measurable concentrations of anti-DNP antibodies late in immunization, but these levels were much lower than those observed in genetic responder animals. Furthermore, strain 13 guinea pigs immunized with DNP-GL and large amounts of mycobacteria failed to produce detectable concentrations of anti-DNP antibodies. All non-responder guinea pigs lacking the PLL gene, immunized with these antigens in adjuvants containing either low or high amounts of mycobacteria, failed to show delayed sensitivity to these antigens. In addition, lymph node cells from these immunized animals were not stimulated in vitro by DNP-PLL. The experimental data suggest that in non-responder guinea pigs the positively charged DNP-PLL molecule behaves as a hapten and that mycobacterial antigens, when present in large amounts, act as an immunologic carrier or “Schlepper” molecule.