Postnatal development of T-lymphocyte subpopulations in the intestinal intraepithelium and lamina propria in chickens.

Postnatal development of various T-lymphocyte subpopulations expressing CD3, CD8, CD4, and antigen-specific TCR heterodimers alpha beta (TCR2) or gamma delta (TCR1) was investigated in two different inbred chicken strains, SC and TK. The ratios of jejunum T-cells expressing TCR1 to TCR2 in the intraepithelium of SC and TK strains gradually increased after hatching and were 3.40 and 4.28 by 12 weeks in TK and SC chickens respectively. The ratios of TCR1+ to TCR2(+)-cells in intraepithelium and the lamina propria in SC chickens were 0.96 and 1.23 at 8 weeks and 4.29 and 2.15 at 12 weeks, respectively. Jejunum intraepithelial lymphocytes expressing the CD8 antigen increased gradually until 4-6 weeks of age and subsequently declined as chickens aged. CD4(+)-cells represented a minor subpopulation among the intestinal lymphocyte subpopulations. Therefore, the composition of various T-cell subpopulations in the intestine depended upon host age, the regions of the gut examined and host genetic background. These results suggest that changes in T-cell subpopulations in the intestine may reflect age-related maturation of the gut-associated lymphoid tissues.