Effects on the Immune System 407Fig. 1.Identification of cannabinoid receptor mRNA in mouse and rat tissues and cells. For detection of CB 1
or CB 2 mRNA, total nucleic acid was subjected to reverse mutagenic reverse transcription-polymerase chain
reaction (MRT-PCR) as described by Carlisle et al. (2002). The bands designatedgDNArepresent amplified
genomic DNA used as an internal quantitation standard. The bands designatedmRNArepresent product
amplified from receptor message. TheP388D1andRAW264.7designate murine macrophage-like cells, while
B103designates rat neuroblastoma cells
Fig.2A,BImmunohistochemicallocalizationofCB 2 receptorsingerminalcentersinmousespleen.Anaffinity-
purifiedantibodytotheamineterminaldomainofthemurineCB 2 wasusedinconcertwithimmunoperoxidase
staining.AImmunoreactive product is localized in germinal centers enriched for B lymphocytes (arrow).
Magnification: X50.BImmunoreactive product for the CB 2 receptor in B lymphocytes is concentrated at the
outer periphery of the cytoplasmic compartment (arrows). ×500
highest amount of CB 2 protein. Dual color confocal microscopy performed on
human tonsillar tissue demonstrated a marked expression of CB 2 receptors in
mantle zones of secondary follicles, whereas germinal centers were weakly stained,
suggesting a modulation of this receptor during B lymphocyte differentiation
stages from virgin B lymphocytes to memory B cells. In addition, protein for the
CB 1 and CB 2 receptors has been identified in neonatal rat microglia maintained in
vitro (Carlisle et al. 2002; Sinha et al. 1998; Waksman et al. 1999).
Levels of cannabinoid receptors on cells of the immune system may vary during
cell differentiation, activation, or response to external stimuli. Noe et al. (2000) re-
portedthatanti-CD40,anti-CD3,andIL-2stimulationinducedcontrastingchanges