LYMPHATIC MAST-CELL RESPONSE AND EFFECT OF COMPOUND-48 80 ON POPLITEAL LYMPH-NODE REACTION IN RATS FOLLOWING INTRACUTANEOUS INJECTION OF STAPHYLOCOCCUS-AUREUS/

To investigate the significance of mast cells in the popliteal lymph n ode during the development of an inflammatory response, rats were inoc ulated with 12 x 10(7) colony-forming units of Staphylococcus aureus i n the hind foot pad. Numerical changes in mast cells were then measure d in the corresponding popliteal lymph node. Six days after inoculatio n, despite the enlargement of the responding lymph node, a marked decr ease in granulated mast cell number, relative to the contralateral nod e, was observed in the cortical and medullary compartments. Popliteal lymph nodes from rats treated with compound 48/80 and then inoculated with S. aureus showed a higher cortical and medullary hypertrophic res ponse and a significant increase in degranulated/weakly basophilic mas t cell number in the lymph node tissue. The findings suggest that (1) Staphylococcus nul eus induces a reduction in granulated mast cell num ber in the cortical and medullary compartments of regional lymph nodes ; (2) pretreatment with compound 48/80 appears to contribute to the ly mphoid cell proliferation and the hypertrophic response of lymph nodes induced by S. aureus; and (3) granulated mast cells have a regulatory role on lymphoid cell proliferation.