IMMUNOLOGICAL RESPONSE IN MICE AFTER LONG-TERM STIMULATION WITH CELL-WALL ANTIGENS FROM BRUCELLA-MELITENSIS

The continuous stimulation of the immune system using cell wall antige ns from Brucella melitensis was found to cause both quantitative and q ualitative changes in circulating lymphocyte populations in mice. Anim als were inoculated in the hind legs with antigens on alternate days f or varying lengths of time. During a two-month period, we saw a higher number of circulating lymphocytes, with an increase in the number of CD4+ cells (L3T4(+)) and B lymphocytes (I-A(d)). After two months, a d rop in the overall number of circulating lymphocytes occurred, with a decrease in CD4(+) cells and an increase in CD8(+) cells. During the f irst two months, we observed a size increase in popliteal lymph nodes and an elevated humoral response. The response then waned with the dec lining CD4(+) cells. In the first two months, the treated animals also showed an in vitro response to two mitogens, concanavalin A and lipop olysaccharide and to the cell wall fraction, after which the treated a nimals showed a decreased response.