A functional role for signal transduction via the cytoplasmic domains of MHC class II proteins

• Published in: The Journal of immunology (1950) Vol. 143; no. 3; pp. 808 - 812
• Main Authors: St-Pierre, Y, Nabavi, N, Ghogawala, Z, Glimcher, LH, Watts, TH
• Format: Journal Article
• Language: English
• Published: United States Am Assoc Immnol 01.08.1989
• Subjects: Animals; Antigen-Presenting Cells - drug effects; Antigen-Presenting Cells - immunology; Antigen-Presenting Cells - physiology; Bucladesine - pharmacology; Cell Line; Cytoplasm - immunology; Cytoplasm - physiology; Epitopes - immunology; Fixatives; Histocompatibility Antigens Class II - genetics; Histocompatibility Antigens Class II - immunology; Lymphocyte Activation; Lymphoma - immunology; Mice; Signal Transduction - drug effects; T-Lymphocytes - immunology; T-Lymphocytes - physiology
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.143.3.808

B cell transfectants expressing MHC class II (Ia) molecules with truncated cytoplasmic domains are defective in both antigen presentation and in anti-Ia induced intracellular signaling. In this report we show that the Ag presentation defect in a truncated-Ia expressing transfectant can be overcome by providing the second messenger for the Ia-mediated signaling event. Preincubation with dibutyryl-cAMP restored the ability of the truncated Ia expressing-transfectant to stimulate IL-2 release by otherwise nonresponsive T hybrids. This provides direct functional evidence that signaling via the cytoplasmic domains of MHC class II proteins leads to the generation of accessory signals in the B cell that are important in T cell activation. The dibutyryl-cAMP induced signal must be on the same cell as the restricting element, does not bypass the requirement for occupancy of the T cell receptor with its normal ligand, and is lost upon fixation of the cells. Thus T cell-B cell interaction involves a two way communication in which both cells sense and respond to the formation of the antigen/MHC/TCR complex.