Immunoglobulin Production Stimulation by Various Types of Caseins
α-, ß-, and k caseins are immunoglobulin production stimulating factors (IPSFs), which stimulate proliferation and immunoglobulin production of hybridomas in serum-free media. To localize the proliferation stimulating and IPSF active sites of these caseins, effects of exopeptidase digestions on these activities of caseins were examined. Carboxypeptidase Y and aminopeptidase M digestions of caseins showed that both C- and N-terminals are important for their proliferation stimulating and IPSF activities. When synthesized a-casein peptides were added to human-human hybridoma HB4C5 cells, four peptides (1–20, 16–35, 91–110, and 106125) stimulated their proliferation, but no peptide showed IPSF activity. When the peptides were added to human lymphocyte cultures in the presence of lipopolysaccharides, four peptides belonging to the 31–95 region stimulated IgG production and four peptides (31–45, 46–65, 76–95, and 151–170) stimulated IgM production. These results suggest that various parts of caseins are related to the proliferation stimulating and IPSF activities.
KeywordsHuman Lung Adenocarcinoma Immunoglobulin Production HB4C5 Cell Proliferation Stimulate Human Lymphocyte Culture
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