Rat interleukin-2 immunoglobulin M fusion proteins are cytotoxic in vitro for cells expressing the IL-2 receptor and can abolish cell-mediated immunity in vivo.
A hybrid cDNA coding for a fusion protein between rat interleukin 2 (IL-2) and a truncated heavy chain from rat immunoglobulin M (IgM) was constructed. The rat IL-2 and rat IgM CH2-3-4 hybrid gene was subcloned into a vector (PKCR6) for expression of the fusion molecule in Chinese hamster ovary (CHO) cells. Cells transfected with the hybrid cDNA secrete multimeric forms of the fusion protein (IL-2-Mu). Size analysis of the construct revealed that the majority (95%) of the secreted proteins have a high mw (> 500 kDa). The IL-2-Mu construct bind specifically to cells bearing the IL-2 receptors (IL-2R) with a binding affinity around 5 nM. The specific binding to IL-2R leads to T cell proliferation or, if rabbit complement is added, to T cell lysis. Multimeric forms (> 500 kDa) of the fusion protein mediate complement-dependent lysis but trigger only weak proliferation when compared with the low-mw forms (< 500 kDa). In contrast, the latter only efficiently mediate T cell proliferation without inducing complement-dependent lysis. After intravenous administration of CHO supernatant containing IL-2-Mu, or purified IL-2-Mu proteins into rats, the fusion proteins disappeared from the circulation with a t1/2 of 1 hr. The circulating IL-2-Mu constructs in the rat serum retained their capacity to induce complement-dependent lysis of IL-2R-bearing T cells in vitro. Furthermore, the IL-2-Mu construct was able to suppress the delayed-type hypersensitivity (DTH) reaction (an IL-2R, T helper cell-dependent event) in mice. A weak immune response (antirat IL-2-Mu antibodies) was observed when rats received multiple daily injections of the construct.
Bogers
W M
WM
Institut National de la Santé et de la Recherche Médicale (INSERM U211), Institut de Biologie, Nantes, France.
Lang
F
F
Parker
K E
KE
Le Mauff
B
B
Anegon
I
I
Jacques
Y
Y
Soulillou
J P
JP
D000818:Animals; D000917:Antibody Formation; D001483:Base Sequence; D016466:CHO Cells / Q000737:chemistry; D002460:Cell Line / Q000737:chemistry; D006224:Cricetinae; D003602:Cytotoxicity, Immunologic; D006968:Hypersensitivity, Delayed / Q000517:prevention & control; D007111:Immunity, Cellular / Q000276:immunology; D007075:Immunoglobulin M / Q000737:chemistry; D007376:Interleukin-2 / Q000276:immunology*; D051379:Mice; D008969:Molecular Sequence Data; D051381:Rats; D011914:Rats, Inbred BN; D015375:Receptors, Interleukin-2 / Q000276:immunology*; D011993:Recombinant Fusion Proteins
D007075:Immunoglobulin M; D007376:Interleukin-2; D015375:Receptors, Interleukin-2; D011993:Recombinant Fusion Proteins