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Lymphocyte proliferation in vitro induced by soluble protein antigens. II. Cellular requirements

Immune guinea pig lymph node cells were fractionated on Ig anti‐Ig or HSA anti‐HSA affinity columns or on plastic surface in medium containing carbonyl iron. These techniques selectively removed B lymphocytes, K lymphocytes or adherent cells. The residual cells (Fc receptor‐negative T lymphocytes) responded to soluble antigen in vitro in the same way or even better compared with nonfractionated cells. In addition, there was no indication that antigen‐antibody complexes were superior to antigen in triggering lymph node cells or purified lymph node T lymphocytes into DNA synthesis. The results obtained suggested that memory T lymphocytes can be stimulated by antigen autonomously.