V.B-cel subsets BI cells(CD5): Many of the first B cells that appear during ontogeny expreSs CD5, a marker originally found on T cells. (express mIgM.no mlgD). They respond well to TI-Ag and may also be involved in the ag processing and presentation to t cells Functions 1. produce anti-bacterial IgM- the first line of defense against microorganisms 2. produce polyreactive Ab- clearance of denatured self components 3. produce auto-Ab, thereby participating in the pathogenesis of some autoimmune diseasesIV. B-cell subsets • B1 cells (CD5+ ): Many of the first B cells that appear during ontogeny express CD5, a marker originally found on T cells. (express mIgM, no mIgD). They respond well to TI-Ag and may also be involved in the Ag processing and presentation to T cells. Functions 1. produce anti-bacterial IgM the first line of defense against microorganisms; 2. produce polyreactive Ab clearance of denatured self components; 3. produce auto-Ab, thereby participating in the pathogenesis of some autoimmune diseases