The leukocyte adhesion molecules, mo1, LFA-1 and p150,95 (Leu-CAM) are three surface membrane heterodimers each with a distinct alpha chain linked to a common beta chain. Leu-CAM mediate vital functions such as phagocytosis, chemotaxis, adhesion to endothelium, aggregation, natural killing and cell-mediated cytotoxicity. Genetic defects in the beta chain (Leu-CAM deficiency) prevent surface expression of the heterodimers, impair cellular inflammation and result in life-threatening bacterial infections in man. On the other hand, massive expression of Mo1 (& p150,95) on phagocytes causes these cells to become hyperadherent resulting in tissue injury as demonstrated in hemodialysis-related pulmonary dysfunction and reperfusion injury during myocardial infarction in dogs. During the current funding period we showed that Leu-CAM deficiency is secondary to defects in the beta chain, cloned the mutant beta chain in one patient, cloned the alpha chain of Mo1 and identified the roles of Leu-CAM in host defense and inflammation. The goals for the next funding period are: 1) Elucidate the structural defects in the naturally occurring beta subunit mutants from selected patients with Leu-CAM deficiency as means to understand the hitherto unknown functions of the beat chain. cDNA cloning techniques will be used for this purpose. 2) Reverse the genetic defects in leukocyte adhesion by transfecting the normal beta gene in naturally occurring mutant cell lines derived from Leu-CAM deficient patients. 3) Achieve a detailed understanding of the structural basis for the adhesion- promoting functions mediated by Mo1. This will be done by co- transfecting normal or mutagenized alpha or beta chains and structural and functional analysis of transfectants. Site-directed mutagenesis will be guided by the results obtained in (1) and knowledge of the primary structure of the alpha and beta chains. 4) Identify the ligand (s) for Mo1 by raising monoclonal antibodies to Leu-CAM deficient cells which inhibit leukocyte adhesion and/or by screening granulocyte cDNA libraries with a cDNA probe for I- CAM, the ligand for LFA-1. The proposed studies will provide a basis for future gene therapy in a disease that is invariably fatal. The structure-function correlation should permit identification of the domains in Mo1 heterodimer involved in promoting cell adhesion. This should allow development of peptides that specifically inhibit leukocyte-mediated inflammatory functions thus producing an acquired Leu-CAM deficiency state. In view of the finding that anti-Mo1 monoclonal antibodies reduce the size of myocardial infarction in dogs by 50%, the chemotherapeutic and immunosuppressive potential of these peptides are obvious.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI021964-08
Application #
3132516
Study Section
Cellular Biology and Physiology Subcommittee 1 (CBY)
Project Start
1989-04-01
Project End
1994-03-31
Budget Start
1993-04-01
Budget End
1994-03-31
Support Year
8
Fiscal Year
1993
Total Cost
Indirect Cost
Name
Massachusetts General Hospital
Department
Type
DUNS #
City
Boston
State
MA
Country
United States
Zip Code
02199
Choi, M; Rabb, H; Arnaout, M A et al. (1995) Preventing the infiltration of leukocytes by monoclonal antibody blocks the development of progressive ischemia in rat burns. Plast Reconstr Surg 96:1177-85;discussion 1186-7
Michishita, M; Videm, V; Arnaout, M A (1993) A novel divalent cation-binding site in the A domain of the beta 2 integrin CR3 (CD11b/CD18) is essential for ligand binding. Cell 72:857-67
Colgan, S P; Parkos, C A; Delp, C et al. (1993) Neutrophil migration across cultured intestinal epithelial monolayers is modulated by epithelial exposure to IFN-gamma in a highly polarized fashion. J Cell Biol 120:785-98
Arnaout, M A (1993) Cell adhesion molecules in inflammation and thrombosis: status and prospects. Am J Kidney Dis 21:72-6
Maruiwa, M; Mizoguchi, A; Russell, G J et al. (1993) Anti-KCA-3, a monoclonal antibody reactive with a rat complement C3 receptor, distinguishes Kupffer cells from other macrophages. J Immunol 150:4019-30
Rabb, H; Michishita, M; Sharma, C P et al. (1993) Cytoplasmic tails of human complement receptor type 3 (CR3, CD11b/CD18) regulate ligand avidity and the internalization of occupied receptors. J Immunol 151:990-1002
Fathallah, D M; Cherif, D; Dellagi, K et al. (1993) Molecular cloning of a novel human hsp70 from a B cell line and its assignment to chromosome 5. J Immunol 151:810-3
Parkos, C A; Colgan, S P; Delp, C et al. (1992) Neutrophil migration across a cultured epithelial monolayer elicits a biphasic resistance response representing sequential effects on transcellular and paracellular pathways. J Cell Biol 117:757-64
Parkos, C A; Delp, C; Arnaout, M A et al. (1991) Neutrophil migration across a cultured intestinal epithelium. Dependence on a CD11b/CD18-mediated event and enhanced efficiency in physiological direction. J Clin Invest 88:1605-12
Schwartz, D; Wong, R C; Chatila, T et al. (1989) Proliferation of highly purified T cells in response to signaling via surface receptors requires cell-cell contact. J Clin Immunol 9:151-8

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