T-CELL MEDIATION OF ABNORMALLY LOW PRODUCTION OF OVALBUMIN-SPECIFIC IMMUNOGLOBULIN-A IN PATIENTS ALLERGIC TO EGGS

Cells producing IgA specific to ovalbumin (OVA) were detected with an assay of plaque-forming cells (PFC). Non-T cells were separated on a p olystyrene resin column and were further depleted of B cells that boun d sheep erythrocytes (SRBC) by SRBC-rosette sedimentation. The cells w ere recombined with T cells separated on a polystyrene resin column, s timulated with OVA antigen, and then cultured for 5 d. The number of O VA-specific IgA-PFC from the lymphocytes of infants allergic to hen's eggs (7 +/- 5 per 7 X 10(4) non-T cells, n = 9) was significantly less than that of PFC from lymphocytes of age-matched controls (110 +/- 18 per 7 X 10(4) non-T cells, n = 7) and from those of children with ato pic dermatitis who were not allergic to hen's eggs (90 +/- 30 per 7 x 10(4) non-T cells, n = 4). Patients' B cells added to the culture supe rnatant from OVA-stimulated normal T cells (82 +/- 18 per 7 X 10(4) no n-T cells, n = 4) were able to produce the specific IgA to levels comp arable to those of normal B cells (92 +/- 9 per 7 X 10(4) non-T cells, n = 6), but the patients' T cells did not cause normal B cells to pro duce the antibody (8 +/- 2 per 7 X 10(4) non-T cells, n = 4), This ind icates that the patients' T cells were less able than were normal T ce lls to promote the production of OVA-specific IgA-PFC. Until the age o f 6 y, the ability of the patients' lymphocytes to produce specific Ig A was abnormally low; from that age on, it was normal. At the stage of allergen entry, this transiently low production of OVA-specific IgA m ay contribute to the onset of allergy to hen's eggs.