Characterization of lectin isolated from Momordica charantia seed as a B cell activator.
Lectin isolated from the seeds of Momordica charantia (MCL) is a galactose-specific glycoprotein. To investigate the effects of MCL on cell activation, we analyzed the responses of BALB/c splenocytes, thymocytes, T cells and B cells on MCL stimulation. Proliferation assays showed that MCL selectively stimulates the B cell subset of splenocytes (p<0.05) in a dose and time dependent manner and that this activation proceeds without the involvement of T cells. Flow cytometric analysis revealed that the fluorescein isothiocyanate (FITC)-labeled MCL binds to B cells, which was inhibited by specific sugars, including galactose. Mouse immunoglobulin (Ig) was able to inhibit MCL-induced proliferation of mouse B cells, suggesting MCL stimulates B cell activation via membrane Ig in the B cell surface. Moreover, after 96-h co-culture, MCL triggered splenocytes to produce a large amount of non-specific IgM in culture supernatants (p<0.01). Additionally, MCL was shown to up-regulate the cell activation marker CD86, in a B cell subpopulation distinct from that affected by LPS. These data suggest that MCL is a T cell-independent B cell activator and a polyclonal Ig inducer, and provide further information on the immunomodulatory effect of MCL.
Huang
Li
L
Department of Veterinary Microbiology, University of Miyazaki, Miyazaki 889-2192, Japan.
Adachi
Takumi
T
Shimizu
Yuya
Y
Goto
Yoshitaka
Y
Toyama
Jun
J
Tanaka
Hidenori
H
Akashi
Ryo
R
Sawaguchi
Akira
A
Iwata
Hiroyuki
H
Haga
Takeshi
T
D000818:Animals; D016175:B-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D051940:B7-2 Antigen / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D004306:Dose-Response Relationship, Immunologic; D005690:Galactose / Q000494:pharmacology; D007136:Immunoglobulins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D007155:Immunologic Factors / Q000276:immunology* / Q000302:isolation & purification / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects; D051379:Mice; D008807:Mice, Inbred BALB C; D029777:Momordica charantia / Q000276:immunology*; D037121:Plant Lectins / Q000276:immunology* / Q000302:isolation & purification / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D012639:Seeds / Q000276:immunology; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism
D051940:B7-2 Antigen; D007136:Immunoglobulins; D007155:Immunologic Factors; D037121:Plant Lectins; D005690:Galactose