EXPRESSION OF THE HUMAN-IMMUNOGLOBULIN HEAVY-CHAIN V(H)6 GENE ELEMENTBY FETAL B-LYMPHOCYTES

Fetal B lymphocytes in mice and humans use a limited number of the ava ilable V-H gene segments. Mouse fetal B cells primarily utilize 3' V-H elements, suggesting that the localization of these elements determin es their rearrangement frequency. The previously reported non-random u sage of human V-H genes has been more difficult to explain. In this st udy the authors analysed the expression of the most proximal 3' human V-H element (V(H)6) using a monoclonal antibody (JE-6). V(H)6 expressi on was assessed in various B cell differentiation stages from fetal li ver, bone marrow and spleen at 12-20 weeks of gestation. The authors d emonstrate that the level of V(H)6 expression doss not exceed a stocha stic usage frequency. This suggests that the localization of V(H)6 doe s not significantly promote its expression during human fetal life, an d that other factors must affect the usage of V-H genes during human f etal development.