Protein immunization induces T follicular helper memory cells and nonpolarized T helper (Tnp) memory cells

Acute viral infection generates lineage-committed T helper 1 (Th1) and T follicular helper (Tfh) memory cells that recall their lineage-specific functions following secondary challenge with virus. However, the lineage commitment of effector and memory T helper cells in vivo following protein vaccination is poorly understood. In this study, we analyzed effector and memory CD4+ T cell differentiation following adjuvanted glycoprotein immunization compared to acute lymphocytic choriomeningitis virus (LCMV) infection. Glycoprotein immunization-induced CXCR5-non-Tfh effector and memory CD4+ T cells that surprisingly had not undergone polarization toward any particular T helper cell lineage but had undergone memory differentiation. However, upon challenge with virus, these T helper lineage-nonpolarized memory CD4+ T cells were able to generate Th1 secondary effector cells, demonstrating their lineage plasticity. In addition, Tfh and memory Tfh cells were generated in response to protein immunization, and these cells differed from infection-induced Tfh cells by their lack of the transcription factor Tbet. Rechallenge experiments demonstrated that viral infection, but not protein immunization, during either the primary or secondary immune response, restricts the recall of Bcl6 expression and the generation of germinal center Tfh cells. Together, these data demonstrate that protein immunization generates a combination of nonpolarized memory cells that are highly plastic and memory Tfh cells that can undergo further Th1-like modulation during a secondary response to viral infection.

Astigmatism and toric intraocular lenses

The article reviews some of the basic optics of astigmatism and the correction of astigmatism with cylindric lenses. A simple model of the conoid of Sturm is demonstrated, and an ideal position for the conoid is postulated. The orientation of the conoid shows that leaving patients with some simple myopic "against-the-rule" astigmatism is beneficial to near work, whereas "with-the-rule" astigmatism is beneficial for distant viewing. Surgeons should be less aggressive with patients with with-the-rule and against-the-rule astigmatism and more aggressive with oblique astigmatism. The toric intraocular lens (IOL) should be positioned on axis or, if slightly off axis, err on the side away from the vertical or horizontal meridian so that the resultant cylinder is more vertical or horizontal. Clinically significant rotation of the toric IOL occurs in a few cases, but these can be easily rerotated. Rerotation should be done between the first and second weeks after primary implantation.

Astigmatism and the toric intraocular lens and other vertex distance effects

An intraocular lens with a given cylindrical power will correct a variable amount of cylinder at the spectacle plane. This variability depends not only on the vertex distance but also on the degree of ametropia. The amount of spectacle cylinder corrected will be more for myopes and less for hyperopes. Anterior corneal cylinder (as determined by the keratometer) is a more reliable way of estimating the cylinder needed at the intraocular lens plane.

Langerhans' cell histiocytosis of the eyelid

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