PHENOTYPE: This locus controls an antigen present on 30-40% of T- and B-cells of lymph nodes. The b allele determines presence of Lna1.2 antigen in C57, C58, GR/A, HRS and I/St; the a allele determines absence of antigen in A, AKR, BALB/c, CBA/J and C3H/An. [provided by MGI curators]