Thymus dependence of the immune response: response to the haptenic determinant NIP in mice.

Normal, deprived (thymectomized, irradiated) and reconstituted (thymectomized, irradiated, thymus grafted) CBA mice were immunized with either a polyvalent or a mainly monovalent conjugate of the hapten 3-iodo-4-hydroxy-5-nitrophenylacetic acid and bovine serum albumin. The humoral antibody response to the hapten was determined by the phage inactivation technique. The response of deprived mice was always significantly lower than the response of either normal or reconstituted animals. However, by increasing the dose of antigen in these mice it was possible to elicit some degree of responsiveness, but only in those groups which had received the polyvalent conjugate.