The production and affinity of anti-hapten antibody under the influence of various inhibitory conditions.

The effects of four experimental conditions leading to lower antibody production (minute amount of antigen, excess of antigen, treatment with methotrexate and competition with an unrelated antigen) on the amount and affinity of antibody produced by injecting an optimal immunizing amount of dinitrophenylated bovine serum albumin (DNP-BSA) in adult guinea-pigs were compared. Adequate use of these four conditions resulted in a rather similar degree of inhibition, antibody production averaging 15 per cent of that produced by optimally stimulated animals. Affinity for the hapten DNP-ε-aminocaproic acid of the antibody produced following stimulation with a minute amount of antigen or following treatment with methotrexate was found to be closely similar to the affinity of antibodies produced by optimally stimulated animals, Both immunization with an excess of antigen and immunization with an optimal amount of DNP-BSA mixed with an excess of an unrelated antigen (bovine γ-globulin), led to the production of antibody of low affinity. These results seem to indicate that the competing antigen interfered with the test antigen at the level of the antibody producing cell.