Search PubMed⌕ Search

Biomedical subjects

M H Julius

Publications and source records attributed to M H Julius.

43 records · Page 3Linked to original sources
PubMed1976

Demonstration that IgG memory is carried by IgG-bearing cells.

Memory B cells which give rise to IgG antibody-producing cells were generally assumed to be IgG-bearing cells. However, recent studies indicating that very few IgG-bearing cells exist in lymphoid tissue brought this assumption into question. In this study, we examined directly the question whether IgG-bearing cells contain functional precursors of IgG antibody-producing cells. Using the adoptive secondary immune response, we demonstrated that Ig-1 b-bearing cells, isolated with the fluorescence-activated cell sorter (FACS), are the functional precursors of Ig- 1 b-producing cells. Further, we have enriched IgG2 and IgG1 memory B cells using the FACS. The results show that IgG2-bearing cells are the functional precursors of the IgG2 antibody-producing cells. Likewise, the IgG1-bearing cells are the functional precursors of IgG1 antibody-producing cells. Thus, IgG memory cells have surface IgG which indicates the class and allotype commitment of the memory cell and its progeny antibody-forming cells.

Animals↗
PubMed1974

Isolation of antigen-binding cells from unprimed mice: demonstration of antibody-forming cell precursor activity and correlation between precursor and secreted antibody avidities.

Cells binding DNP groups conjugated to fluoresceinated mouse gamma globulin ((F)DNP-MGG) were isolated from spleens of unprimed mice using a fluorescence-activated cell sorter (FACS). The isolated cells were specifically enriched at least 100-fold for anti-DNP precursor activity in an adoptive transfer assay as compared to unfractionated spleen. The fraction depleted of binding cells, although depleted of anti-DNP precursor activity, responded as well as unfractionated spleen when assayed for anticarrier (keyhole limpet hemocyanin [KLH]) precursor activity. High avidity binding cells were stained using low concentrations of (F)DNP-MGG. Medium and low avidity binding cells were stained using high concentrations of (F)DNP-MGG in the presence of free hapten which selectively blocked staining of the high avidity binding cells. Cells were supplemented with an excess of carrier-primed (KLH), nylon-purified splenic T cells and transferred to irradiated recipients. DNP-KLH was given at transfer and 5 days later. The anti-DNP plaque-forming cell (DNP-PFC) response and the avidities of the DNP-PFC in the irradiated recipients were measured by hapten inhibition of direct PFC plaque formation 12 days after transfer. At this time, very few indirect PFC were found. There was a positive correlation between the avidity of the DNP-binding cells and the avidity of the anti-DNP antibody secreted by their progeny. High avidity DNP-binding cells gave rise to predominantly high avidity anti-DNP-PFC. Medium and low avidity binding cells gave rise to medium and low avidity DNP-PFC.

Animals↗
PubMed1972

Demonstration that antigen-binding cells are precursors of antibody-producing cells after purification with a fluorescence-activated cell sorter.

We have obtained viable and functional populations of antigen-binding cells enriched up to 500-fold from primed spleen-cell suspensions by fluorescent labeling and by a new electronic cell sorter that sorts viable cells according to fluorescence. Concomitantly, populations largely depleted of antigen-binding cells were obtained. While neither population alone is capable of a full adoptive secondary response when injected into irradiated recipients, a reconstituted mixture restores the full response of the unfractionated spleen cells. Admixture of sources of unprimed thymus-derived cells (T-cells) with the purified antigen-binding cells (B-cells) restores much of the full response.

Animals↗
PubMedDate not supplied

Effector and regulator functions of splenic and thymic lymphocytes in the clawed toad Xenopus.

B cells in Xenopus, as characterized by surface immunoglobulin, nylon-wool adherence and ability to produce antibody in vitro, were found in both major lymphoid organs: 10-25% Ig-positive cells for spleen and 0.5-4% for thymus. The splenic and thymic B cells were able to produce specific antibody of both isotypes, IgM and low molecular weight (LMW) Ig (IgG equivalent). While for a T-cell-dependent antigen, DNP-KLH, both required T-cell help, thymic B cells for a specific antigen produced far more LMW Ig than splenic B cells. Thymic T cells had the same ability as splenic T cells to elicit an allogenic GvH, but with much less efficiency, probably as a result of fewer mature cells. In contrast to splenic T cells, thymic T cells provided little or no help for B cells and, in certain instances, demonstrated suppressor activity.

Animals↗