Marrow Colony-Forming Units: Age-Related Changes in Responses to Anti-θ-Sensitive Helper/Suppressor Stimuli 1

Abstract

Abstract

Earlier studies with the anemic W/W^v mouse and healthy aged mice have revealed the presence in bone marrow of an anti-θ-sensitive regulatory cell (TSRC) with “helper” function. In experiments presented here, treatment of marrow cells from young mice with anti-θ serum or anti-Ly-1.2 serum and complement had no effect on the number of spleen colonies formed in irradiated recipients; similar treatment of marrow cells from old donors, however, resulted in a 40% reduction in colonies which was reversed if young thymus cells were added to the inoculum. When marrow cells from young or old mice injected 4 days before with SRBC were treated with anti-θ or anti-Ly-2.2 serum and complement, spleen colonies increased by about 50%; treatment of the same cells with anti-Ly-1.2 serum had no significant effect on colony formation. Marrow cells from immunized young and old donors treated with anti-θ serum and complement had no colony inhibitory activity when mixed with marrow from normal young donors; however, the same cells were highly inhibitory to CFU-S from old donors. These observations demonstrate the presence in mouse marrow of distinct TSRC populations with CFU-S helper and suppressor functions. Other findings suggest that in old mice one or several CFU regulatory mechanisms are disturbed and/or responses to them are defective.