Antibody response to bacteriophage theta-X 174 in vitro: demonstration of immunological memory in terms of IgM and IgG responses.

Abstract

AbstractThe initiation of a primary‐type antibody response to bacteriophage ϕX 174 has been studied in organ cultures of lymph nodes from normal rabbits. Lymph nodes are also removed for culture at various times following a primary injection of ϕX in the rabbits and their responsiveness to a second anti‐genic stimulus investigated. All the cultures are maintained for 2 to 4 weeks and the antibody responses followed throughout. The following points are shown. The ability of non‐primed lymph node fragments to initiate a primary type response in responding to ϕX stimulation in vitro declines rapidly during the first 2 ‐ 3 days and is lost after 3 days of culture. An apparent failure to develop a primary IgG response is shown in cultures of non‐immunized lymph nodes even when the antigen was given for 1 to 6 days continuously or given twice, once on day 0 to 1 and another time on day 2, 3, 4, or 5. Following antigenic stimulation in vitro, cultures of lymph nodes from rabbits immunized one (to two) days previously produce an antibody response of primarly IgM antibodies with a geometric mean significantly smaller than that produced by non‐primed lymph node cultures. Cultures of primed lymph nodes without a secondary antigenic stimulation in vitro produce antibodies only of the type present in the animal at the time of the tissue removal. Cultures of lymph nodes from rabbits immunized more than 4 days previously exhibit IgM and IgG memories. The secondary response initiated in vitro exhibits predominantly IgM memory when cultures are of nodes primed in vivo 4 days previously, but exhibits primarily IgG memory when cultures are of nodes primed in vivo 14 days previously. Intermediate proportions of IgM and IgG are seen at intermediate time intervals. The ability of primed lymph nodes to show the phenomenon of memory appears to be positively correlated in time with the ability to develop IgG antibodies. IgM memory is transient in the sense that it is exhibited only in lymph nodes primed in vivo less than 2 weeks previously, whereas IgG memory lasts as long as the life of the animal.