Analysis of germinal centres in the immune response to oxazolone.

In a primary T-cell dependent immune response B-cell proliferation is observed in two areas of the spleen. In the first days after immunisation expansion of B-cell clones can be observed in the periarteriolar lymphocyte sheath. Here the development of plasma cells seems to take place. Then, around day 3 to day 4, antigen activated B-cells start to proliferate in the primary follicles. This leads to the formation of the germinal centre within which memory cells develop. The analysis of germinal centre B-cells at different timepoints after immunisation has shown that between days 10 and 14 somatic mutations rapidly accumulate in the variable regions of the antibody molecules (Berek et al, 1991). There is intraclonal diversification of the B-cell repertoire in the geminal centres (Jacob et al., 1991). We have now isolated DNA from single germinal centres of mice immunised with the hapten 2-phenyl-oxazolone (phOx). The data demonstrate that the affinity maturation of the primary immune response takes place in the germinal centres.