Murine lymphocyte surface antigens

Unusual human lymphoma phenotype defined by monoclonal antibody

The phenotype of three large cell (histiocytic) lymphomas of man has been defined with convential lymphocyte surface marker techniques, a panel of monoclonal antisera of hybridoma derivation (Ortho Pharmaceutical Corp.), and the fluorescence microscope. Two tumors exhibited surface IgG of lambda light-chain type, whereas the third was negative for surface Ig but contained the same Ig in the cytoplasm. With the monoclonal antisera, all three were found to bear two surface antigens (OKT9 and OKT10) previously described on early thymocytes, and were devoid of the Ia antigen. The available knowledge suggests that these neoplasms represent the expansion of a clone of B lymphocytes along the pathway that leads to plasma cell differentiation rather than a clone with both B and T surface membrane markers.

Cell membrane alloantigenic determinants of several unusual mouse strains

Several interesting and clinically important strains of Mus musculus were serotyped with alloantisera recognizing the different alleles of the Thy-1, Ly-1, Ly-2, Ly-3, Ly-4, Ly-5, Ly-6 and Ly-7 loci. The strains were the Biozzi high and low responder strains, or importance in immune responsiveness studies, and the strains BXSB, MRL and MRL--lpr/lpr--strains which spontaneously develop immune complex disease. In addition the related species Mus musculus casteneus was typed with the same reagents. The knowledge of the cell surface phenotype should prove useful in various functional studies involving these interesting strains.

A monoclonal antibody detecting the Ly-9.2 (Lgp 100) cell-membrane alloantigen

A mouse monoclonal cell line (20-1.5) was produced by the cell fusion method and the antibody secreted by this line defined the Ly-9.2 specificity--the reciprocal specificity to that previously identified as the Lgp 100 or the T100 molecule. Although most concentrated on lymph-node cells, the antigen is also found on thymocytes, spleen and bone-marrow cells as well as liver and brain tissue. The monoclonal antibody precipitates a 100,000 molecular moiety from thymocytes. The antigenic specificities appear to be highly immunogeneic and antibodies to these specificities contaminate many antisera. These sera are noncytotoxic as is the case with the monoclonal antibody even though it is of the IgG2a subclass. As with T100 or Lgp 100, the Ly-9 locus appears to be linked to the H-25 locus.

High titres of antibody to murine leukaemia virus in lymphocyte (Ly) alloantisera

The radioimmune precipitation (RIP) assay was used to examine the antibody titres against endogenous AKR murine leukaemia virus (MuLV) in a number of antisera to lymphocyte (Ly) alloantigens. The sera from normal donor and unimmunized recipient mice used in raising the alloantisera were also examined for anti-MuLV activity. It was found that all the antisera had high anti-MuLV titres and that in all but one case alloantigen immunization augmented the anti-viral titres. The degree of augmentation did not appear to be related to the anti-MuLV titre in the donor strain sera. Three I-region antisera were also examined for anti-MuLV antibodies and were found to have lower anti-viral titres than the Ly antisera even though immunization to I-region products greatly augmented the anti-viral titre. These results caution against the use of Ly antisera in characterizing the phenotype of lymphoid tumour cells without prior virus absorption.

Molecular weight determination of two genetically linked cell surface murine antigens: ThB and Ly-6

Various murine tumor lines were screened by FACS analysis for the surface antigens ThB and Ly-6.2. Positive cell lines were used for immunoprecipitation studies. A monoclonal ThB-specific antibody immunoprecipitated a unique acidic protein of approximately 16 000 daltons from several positive tumors and from concanavalin A (Con-A) and LPS activated splenic lymphocytes. Monoclonal Ly-6.2-specific antibody was used to immunoprecipitate a 33 500 dalton protein that was shown to exist in four similarly sized forms with different basic charges. In the course of these studies, the apparent molecular weight of the surface antigen T 30, immunoprecipitated with a monoclonal T 30-specific antibody from the cell line EL4, was found to be approximately 25 000 daltons.