Plant species produce lectins, defensive proteins that bind to carbohydrates or carbohydrate-containing proteins.

TLS Online TPP Program

#Id: 1887

#Unit 4. Cell Communication and Cell Signaling

Time course of appearance of  thymocytes and  thymocytes during mouse fetal development.

TLS Online TPP Program

#Id: 1888

#Unit 4. Cell Communication and Cell Signaling

Allelic exclusion

Most T cells fully rearrange and express a TCR chain from only one of their two TCR alleles

TLS Online TPP Program

#Id: 1889

#Unit 4. Cell Communication and Cell Signaling

Thymic selection

The most distinctive property of the mature T cells is that they recognize only foreign antigen combined with self-MHC molecules.

TLS Online TPP Program

#Id: 1890

#Unit 4. Cell Communication and Cell Signaling

Two distinct selection processes are required:

 • Positive selection, which selects for those thymocytes bearing receptors capable of binding self-MHC molecules, resulting in MHC restriction

• Negative selection, which selects against thymocytes bearing high-affinity receptors for self-MHC/peptide complexes, resulting in self-tolerance.

TLS Online TPP Program

#Id: 1891

#Unit 4. Cell Communication and Cell Signaling

T-cell education

TLS Online TPP Program

#Id: 1892

#Unit 4. Cell Communication and Cell Signaling

Relationship between TCR affinity and selection