CELLULAR IMMUNOLOGY 66, 254-268 (1982) Involvement of Human Membrane-Associated Complement Components in the Rosette Formation between Marmoset Red Blood Cells and Human Leukocytes JEAN-LUC TEILLAUD,**’ C~CILE GOUJET-ZALC,* MARC FoNTAINE,t COLETTE BRAUN,* AND GUY MAHOUY* *Institut de Recherches sur les Maladies du Sang, Laboratoire des Interactions lymphocytaires, HGpital Saint-Louis, 75475 Paris Cedex IO, and tINSERM U78. 543 Chemin de la BretZque, 76230 Bois-Guillaume, France Received July 15, 1981; accepted October 28, 1981 The majority of human monocytes, a subpopulation of B lymphocytes, and all B lympho- blastoid cell lines (B-LCL) tested but one form rosettes with Marmoset red blood cells (MaRBC). None of the human peripheral T cells, T-LCL, and B chronic lymphoid leukemia cells (B-CLL) used bind to MaRBC. The binding could not be correlated with any membrane markers or antigens present on cultured cells or peripheral blood leukocytes (PBL). Blocking of the rosette formation by preincubation of MaRBC with purified human complement (C) components and cobra venom or by pretreatment of leukocytes and cultured cells with antisera to human C components suggested that membrane-associated C components present on PBL or B-LCL are involved in the binding to MaRBC. INTRODUCTION Monkey erythrocytes form spontaneous rosettes with human leukocytes; however, conflicting data have been reported: Pellegrino et al. claimed that human B lym- phocytes have receptors for Mucaca speciosa red blood cells ( 1) whereas Lohrmann and Novikovs reported that rhesus erythrocytes bind to human T cells (2). There have also been recent studies showing the detection of membrane-associated com- plement (C)2 components on circulating human leukocytes and on cultured cells ’ To whom correspondence should be sent. *Abbreviations used: ALL, acute lymphocytic leukemia; BL, Burkitt lymphoma; j32-m, &micro- globulin; C, complement; CLL, chronic lymphoid leukemia; CML, chronic myelocytic leukemia; CRl, complement receptor type one, the immune adherence C4b-C3b receptor; CR2, complement receptor type two, the C3d receptor; CVF, cobra venom factor; EAC”, sheep erythrocytes sensitized with rabbit IgM anti-sheep erythrocytes and mixed with fresh mouse serum; EBV, Epstein-Barr virus; EDTA, ethylenediaminetetraacetic acid; EGTA, ethylene glycol tetraacetic acid; FcyR, receptorfor the Fc fragment of IgG; FcpR, receptor for the Fc fragment of IgM; FCS, fetal calf serum; FITC-SRBC, fluoresceinated sheep red blood cells; IA, immune adherence; LCL, lymphoblastoid cell line; MaRBC, marmoset red blood cells; PBL, peripheral blood leukocytes; PNA, peanut agglutinin; RFC, rosette- forming cells; SDS-PAGE, sodium dodecyl sulfate-polyacrylamide gel electrophoresis; SIg, cell surface immunoglobulin; TRITC-(Fab’)* anti-r, tetramethylrbodamine isothiocyanate conjugated to (Fab’), fragment of rabbit IgG anti-human ~1 chain. 254 0008-8749/82/020254-l 5$02.00/O Copyright 0 1982 by Academic Press, Inc. All rights of reproduction in any form rese~cd.