<P> It is impossible to distinguish between T cells and B cells in a peripheral blood smear . Normally, flow cytometry testing is used for specific lymphocyte population counts . This can be used to determine the percentage of lymphocytes that contain a particular combination of specific cell surface proteins, such as immunoglobulins or cluster of differentiation (CD) markers or that produce particular proteins (for example, cytokines using intracellular cytokine staining (ICCS)). In order to study the function of a lymphocyte by virtue of the proteins it generates, other scientific techniques like the ELISPOT or secretion assay techniques can be used . </P> <Dl> <Dd> <Table> Typical recognition markers for lymphocytes <Tr> <Th> Class </Th> <Th> Function </Th> <Th> Proportion </Th> <Th> Phenotypic marker (s) </Th> </Tr> <Tr> <Th> Natural killer cells </Th> <Td> Lysis of virally infected cells and tumour cells </Td> <Td> 7% (2--13%) </Td> <Td> CD16 CD56 but not CD3 </Td> </Tr> <Tr> <Th> T helper cells </Th> <Td> Release cytokines and growth factors that regulate other immune cells </Td> <Td> 46% (28--59%) </Td> <Td> TCR αβ, CD3 and CD4 </Td> </Tr> <Tr> <Th> Cytotoxic T cells </Th> <Td> Lysis of virally infected cells, tumour cells and allografts </Td> <Td> 19% (13--32%) </Td> <Td> TCR αβ, CD3 and CD8 </Td> </Tr> <Tr> <Th> Gamma delta T cells </Th> <Td> Immunoregulation and cytotoxicity </Td> <Td> 5% (2--8%) </Td> <Td> TCR γδ and CD3 </Td> </Tr> <Tr> <Th> B cells </Th> <Td> Secretion of antibodies </Td> <Td> 23% (18--47%) </Td> <Td> MHC class II, CD19 and CD20 </Td> </Tr> </Table> </Dd> </Dl> <Dd> <Table> Typical recognition markers for lymphocytes <Tr> <Th> Class </Th> <Th> Function </Th> <Th> Proportion </Th> <Th> Phenotypic marker (s) </Th> </Tr> <Tr> <Th> Natural killer cells </Th> <Td> Lysis of virally infected cells and tumour cells </Td> <Td> 7% (2--13%) </Td> <Td> CD16 CD56 but not CD3 </Td> </Tr> <Tr> <Th> T helper cells </Th> <Td> Release cytokines and growth factors that regulate other immune cells </Td> <Td> 46% (28--59%) </Td> <Td> TCR αβ, CD3 and CD4 </Td> </Tr> <Tr> <Th> Cytotoxic T cells </Th> <Td> Lysis of virally infected cells, tumour cells and allografts </Td> <Td> 19% (13--32%) </Td> <Td> TCR αβ, CD3 and CD8 </Td> </Tr> <Tr> <Th> Gamma delta T cells </Th> <Td> Immunoregulation and cytotoxicity </Td> <Td> 5% (2--8%) </Td> <Td> TCR γδ and CD3 </Td> </Tr> <Tr> <Th> B cells </Th> <Td> Secretion of antibodies </Td> <Td> 23% (18--47%) </Td> <Td> MHC class II, CD19 and CD20 </Td> </Tr> </Table> </Dd> <Table> Typical recognition markers for lymphocytes <Tr> <Th> Class </Th> <Th> Function </Th> <Th> Proportion </Th> <Th> Phenotypic marker (s) </Th> </Tr> <Tr> <Th> Natural killer cells </Th> <Td> Lysis of virally infected cells and tumour cells </Td> <Td> 7% (2--13%) </Td> <Td> CD16 CD56 but not CD3 </Td> </Tr> <Tr> <Th> T helper cells </Th> <Td> Release cytokines and growth factors that regulate other immune cells </Td> <Td> 46% (28--59%) </Td> <Td> TCR αβ, CD3 and CD4 </Td> </Tr> <Tr> <Th> Cytotoxic T cells </Th> <Td> Lysis of virally infected cells, tumour cells and allografts </Td> <Td> 19% (13--32%) </Td> <Td> TCR αβ, CD3 and CD8 </Td> </Tr> <Tr> <Th> Gamma delta T cells </Th> <Td> Immunoregulation and cytotoxicity </Td> <Td> 5% (2--8%) </Td> <Td> TCR γδ and CD3 </Td> </Tr> <Tr> <Th> B cells </Th> <Td> Secretion of antibodies </Td> <Td> 23% (18--47%) </Td> <Td> MHC class II, CD19 and CD20 </Td> </Tr> </Table>

Where are t cells and b cells produced