Characterization and distribution of B cells in the lymphoid organs of goats

The distribution of B cells in the lymphoid organs of the goat was studied using a panel of 13 monoclonal antibodies (mAbs) developed against differen t markers for bovine B cells. Samples of mesenteric lymph nodes, jejunal an d ileal Peyer's patches, duodenum, jejunum, ileum, colon, caecum and rectum were taken from four 7-month-old male Murciano-granadina goats using the a vidin-biotin-peroxidase (ABC) method on frozen sections as described by Hsu et al. (1981). The mAbs against immunoglobulins (Ig) recognized a large nu mber of cells, particularly in the light zones of the germinative centres o f the lymphoid follicles, regardless of the isotype against which they were directed. However, the greatest numbers of B cells in the germinative cent res and outer coronas of the lymphoid follicles of the lymph node, spleen a nd Peyer's patches were recognized by mAbs against the L lambda, chain of I g and against IgM. This was also the case in other locations where B cells were abundant, such as the medulla of the lymph node and the dome of the Pe yer's patches. These mAbs recognized not only B lymphocytes but also plasma cells, showing an intracytoplasmatic reaction (numerous in the spleen red pulp and the intestinal lamina propria when mAbs were used against the L la mbda chain of the Ig, scarce in the intestinal lamina propria when used aga inst IgM and scarce in spleen red pulp and numerous in the intestinal lamin a propria when mAbs against IgA were used). The mAbs BAQ44A, GC65 A and GB2 5 A are of interest because, besides marking cells in the B areas where lym phocytes show surface Ig, they give a positive reaction in areas where ther e are Igcells (the dark zone of the germinative centre) and do not immunost ain plasma cells. Thus, these mAbs recognize a surface marker which is not an Ig.