Laminin-8 (alpha 4 beta 1 gamma 1) is synthesized by lymphoid cells, promotes lymphocyte migration and costimulates T cell proliferation

Laminins are a growing family of large heterotrimeric proteins with cell ad hesive and signalling functions, They are major components of basement memb ranes and are found in many organs, including the vasculature and other com partments of bone marrow, thymus, lymph nodes and spleen, However, expressi on, recognition and use of laminin isoforms by lymphoid cells are poorly un derstood, In the present study, lymphoid T cells (Jurkat) were found to syn thesize laminin alpha4, beta1 and gamma1 mRNAs and polypeptides and to asse mble the chains into laminin-8, Lymphoblastoid B (NAD-20) cells, lymphoid N K (NKL) cells and blood lymphocytes also contained laminin-8 and, after cel l permeabilization, practically all blood lymphocytes reacted with mAbs to laminin beta1 and gamma1 chains, Following stimulation, blood lymphocytes s ecreted laminin-8, and this laminin isoform, but not laminin-10/11(alpha5 b eta1 gamma1/alpha5 beta2 gamma1), promoted chemokine-induced migration of t he cells, In an activation-dependent manner, purified blood CD4 T cells adh ered to immobilized laminin-g and laminin-10/11 by using alpha6 beta1 integ rin, but minimally to laminin-1 (alpha1 beta1 gamma1), Accordingly, laminin -8 and laminin-10/11, but not laminin-1, strongly costimulated proliferatio n of the T cells via the same integrin, Thus, lymphoid cells are able to sy nthesize and secrete complete laminin molecules, In addition, synthesis of laminin-8 and recognition of laminin-8 and -10/11 by lymphocytes indicate r elevance of these laminin isoforms in lymphocyte physiology.