Hypothesis on the time course of antigen dependent changes in lymphoid organs proved by experimental data of depleted growing rats' mesenteric lymph nodes.

The results described in this paper partially agree with the hypothesis that mesenteric lymph nodes (MLN) of depleted growing rats recover their antigen specific determinants after the oral administration of 20% casein for 5-9 days following the time course of antigen dependent changes observed in virgin lymph nodes. With respect to the 39 days old control group, depleted MLN showed a highly diminished number of mature T cells (W3/13+) as well as surface and intracellular alpha heavy chain (alpha s and alpha cit). The oral administration of a 20% casein diet during 5 days tends to restore the appearance of these determinants; however, normal values were not attained even if refeeding was continued for 9 days. The discrepancy between the proposed hypothesis and the observed results might be ascribed to: a) defective migration of T cells from thymus; b) the diminished number of TH cells involved in terminal differentiation; c) inability of B cells to respond to T cell-derived factors.