Functional expression of beta 1 and beta 2 integrins on tumor infiltratinglymphocytes (TILs) in colorectal cancer

Integrins play an important role in various lymphocyte functions. In this s tudy, tumor-infiltrating lymphocytes (TIL) were isolated from colorectal ca ncer tissues and the expression of beta 1 and beta 2 integrins on the TIL w as quantitatively examined with two-color flow cytometry. In comparison wit h peripheral blood lymphocytes (PBL), TIL expressed a lower level of common beta 1 chain (CD29) in both CD4 and CD8 subpopulations. Among the associat ed a chains, the expressions of alpha 1 (CD49a) and alpha 2 (CD49b) were sl ightly higher in TIL than in PBL, whereas alpha 4 (CD-49d) and alpha 6 (CD4 9f) were markedly downregulated in TIL. Both alpha L (CD11a) and beta 2 (CD 18) were reduced in CD8(+) TIL but not in CD4(+) TIL, TIL with the CD8(+) c ytotoxic phenotype showed significantly decreased binding to purified intra cellular adhesion molecules (ICAM)-1, and vascular adhesion cell molecule ( VCAM)-1, and HT29 colon cancer cells, compared with the in counterparts in PBL, The peculiar expression pattern and functional down regulation of thes e integrins may explain why TIL in colorectal cancer cannot eradicate the m alignant cells.