Interference between two immune responses. I.--Modification of the kinetics of the mouse response to SRBC by responses to heterologous RBC.

Influence of a preceding immunization with HoRBC on the immune response to SRBC was studied in Swiss and CBA inbred mice. In Swiss mice, a short interval (1day) between the two immunizations produced an acceleration of anti-SRBC response, while a longer interval (4-7 days) inhibited this response. This was interpreted as manifestations of nonspecific helper and suppressor activities triggered by the previous challenge. At any time of a response, there would exist a variable ratio of these two opposite activities. The helper activity was radiation-resistant while the suppressor one was radiation-sensitive at the time of its appearance and was effective on the IgG as well as on the IgM response. CBA mice response to SRBC was only influenced by the suppressor and not by the helper component of the preceding challenge with HoRBC. These CBA mice were very good responders to this antigen, and this may be the cause of their strain particularities. If we consider that each individual is permanently submitted to natural immunizations, the ratio of the resulting non-specific activities must be esentially variable with time; it can partly account for the individual amplitude variation of an engaged immune response.